tag:blogger.com,1999:blog-8685475766748337002024-02-07T00:08:48.069-06:00It's a bug's lifeI am a field crop extension entomologist at Iowa State University. This blog provides real-time updates on field crop insect IPM. Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.comBlogger103125tag:blogger.com,1999:blog-868547576674833700.post-69277857459376590312014-08-04T15:51:00.001-05:002014-08-04T16:25:40.990-05:00Bee yard visit and maybe the best day of the summerToday my post-doc, Thelma, and I got to go on an adventure and visit a honey bee yard. It's maybe a little embarrassing to say it was my first time seeing hives, maybe because you would assume entomologists get to see this stuff all the time. Well, not so much for this field crop bug girl. I did have a tiny bit of anxiety about the visit. Random questions to myself before the trip...<br />
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First thought: Am I going to freak out with all the buzzing and swarming? I imagined a deafening sound of a thousand bees landing on me and not sure if that was going to send me running back to the car.<br />
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Second thought: Am I going to get stung and by how many bees? Note: I hate being bit by mosquitoes, ticks or anything, really. My last bee sting swelled up substantially and I wasn't looking forward to a puffy welt.<br />
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Third thought: Am I going to get really sticky? I just had an idea of a bee hive being messy with dripping honey everywhere. Not sure why? Note: I don't really like to be covered with sugar.<br />
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Fourth thought: Am I going to sound like an idiot? I know I don't know anything about honey bees, but was very curious. Would I sound and look like a moron? You decide on my look!<br />
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<b>Bee suits aren't very flattering, but I felt protected with the cool head gear!</b></div>
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Thelma and I arranged this meeting with Andy Joseph (IDALS State Apiculturist) and Robin Pruisner (IDALS State Entomologist). They took some time off from their usual jobs to look at a few hives east of Ankeny and talk about honey bees. They both personally own honey bees and have a lot of practical experience raising successful bees in Iowa.<br />
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<b>The colorful boxes hold honey bee colonies. Each tower has it's own queen, workers, and drones.</b></div>
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Andy and Robin showed us various stages of brood and honey production. Rearing healthy and productive honey bees takes a lot of work. Plus it's like they were using another language to describe the process (my entomological background was only mildly helpful). It was also apparent that a beekeeper needs a bunch of specialized tools! The buzzing was surprisingly not bad. I didn't feel like they were out to get me, even though we were popping open "supers" and looking at their babies and potentially taking their food.<br />
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<b>Andy lightly smokes the super before pulling out the frames. I almost sound like I know what I am talking about!</b></div>
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<b>Andy typically only wears the hat with mesh veil. Obviously, he's been working with bees for a long time!</b></div>
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<b>An example of a nicely progressing frame. The queen should start laying eggs in the middle and work her way around. Note the capped cells in the middle and pure honey in the upper right corner. </b></div>
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They seemed to know right away if the bees were making the right pattern. It wasn't as obvious to an untrained eye. Some frames were very organized and others looked like they were created by bees with ADHD. We got to taste some honey straight from the hive. Woot! I am now officially a honey snob and I never EVER want to buy honey from a store again. </div>
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<b>Worker bees forage on pollen and nectar for the colony. Once their bellies are full, they pack extra pollen on their hind legs. Note the bright, yellow pollen balls on these ladies!</b></div>
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<b>Entrance hole for foraging bees. Workers live for a few weeks after emerging from capped cells. </b></div>
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Final thoughts: didn't freak out, didn't get stung, it wasn't sticky and I only kinda sounded ignorant. Overall, a great experience! I can't wait to visit again, perhaps during the honey extraction for an extra tasty adventure!Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-66026623274988854252014-06-11T10:08:00.002-05:002014-06-11T10:08:17.357-05:00Maggots and armywormsIt is that time of year when I hear about maggots and armyworms in field crops. At least that means people are out there looking for insects! I don't always get great photos of the insect activity or injury, but this week is the exception. Keep 'em coming, everyone!<br />
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Brian Lang, ISU Field Agronomist in northeast Iowa, has already found a soybean aphid (actually he almost always finds the first ones every year) AND he found a few prevent plant fields with seed corn maggot in soybean. He seemed to notice more plant feeding in fields that were planted to oats last year compared to radish. He also noted it was a field with mostly naked soybean seed (no insecticidal seed treatment).<br />
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<b>Seedcorn maggot and pupae at the base of an emerging soybean plant. Photos by Brian Lang, ISU. </b></div>
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Tom Hillyer, a crop consultant in Iowa, always sends me interesting photos. He manages to stump me on a regular basis with insect identification. But his recent photos included some developed armyworms feeding on corn. He also found a few bean leaf beetle on soybean despite my <a href="http://www.extension.iastate.edu/CropNews/2014/0409hodgson.htm" target="_blank">earlier prediction</a> for high mortality this year. </div>
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<b>Yellowstriped armyworm. Photo by Tom Hillyer.</b></div>
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<b>Armyworm. Photo by Tom Hillyer.</b></div>
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<b>Bean leaf beetle. Photo by Tom Hillyer. </b></div>
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Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-36607551738896684532014-06-04T14:52:00.002-05:002014-06-04T14:52:58.702-05:00Did this winter kill all the corn rootworm eggs?<div class="MsoNormal">
<span style="font-family: inherit;">Insect mortality happens every winter, even under ideal
conditions. However, this winter was the<a href="http://www.radioiowa.com/2014/01/28/iowa-in-midst-of-9th-coldest-winter-in-121-years-of-records-audio/" target="_blank"> 9th coldest in 121 years</a> and I’ve been getting questions about how the harsh conditions may have
impacted overwintering corn rootworm eggs. Maybe we don’t need to care rootworms
this year if all the eggs froze to death? We’re probably not so lucky. Many
factors besides cold air temperatures influence successful overwintering of
insects in Iowa, including our most important field crop pest.<o:p></o:p></span></div>
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<span style="font-family: inherit;"><br /></span></div>
<span style="font-family: inherit;"><span style="line-height: 115%;">Cold temperatures can kill rootworm eggs; temperatures
below 18.5</span><span style="line-height: 115%;">°</span><span style="line-height: 115%;">F can
be lethal to eggs (Woodson and Gustin 1993). We know the eggs are deposited
into soil cracks and crevices and are somewhat protected to air temperatures. Mike
Gray (University of Illinois) provided a nice <a href="http://bulletin.ipm.illinois.edu/?p=1876" target="_blank">blog summary</a></span><span style="line-height: 115%;"> </span><span style="line-height: 115%;">of research involving soil temperatures, egg
depth and survivorship. To see how cold it really was this winter, I was able
to extract a graph showing soil temperatures at three depths near Ames (1
November 2013 – 1 May 2014). There were several dates where the temperature was
cold enough to kill eggs in the </span><span style="line-height: 115%;">top 12</span><span style="line-height: 115%;">ʺ</span><span style="line-height: 115%;"> of the soil in central Iowa and likely other
places throughout the state. </span></span><br />
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<span style="font-family: inherit;"><b>Soil temperature data courtesy of
Iowa Environmental Mesonet, ISU Department of Agronomy.</b><o:p></o:p></span></div>
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<em><span style="font-family: inherit;"><br /></span></em></div>
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<span style="font-family: inherit;">Egg deposition is highly variable within and between species, but
in general eggs have a better chance of surviving if they are placed deeper in
the soil. Western corn rootworms tend to lay most eggs 4-8ʺ below the soil surface, compared to
northern corn rootworms that tend to lay most eggs in the top 4ʺ (Gray and Tollefson 1988). So the
odds are in favor of more westerns surviving the winter just because of where
females put the eggs. <o:p></o:p></span></div>
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<span style="font-family: inherit;"><br /></span></div>
<div class="MsoNormal">
<span style="font-family: inherit;">Crop residue and snow cover can significantly improve egg
survivorship (Godfrey et al. 1995). However, just how much residue/snow cover
is needed is not fully understood. Tillage and tillage timing does not
significantly reduce egg populations (Gray and Tollefson 1988). Soil texture did
not appear to influence egg mortality in a Nebraska study (Godfrey et al.
1995).<o:p></o:p></span></div>
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<span style="font-family: inherit;"><br /></span></div>
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<span style="font-family: inherit;">Saturated soils do not kill corn rootworm eggs, but they can
negatively impact larvae. When soil is saturated, oxygen can be limited and
cause suffocation. About 50% of third instar western corn rootworm larvae die
in saturated soils after 24 hours (77°F); survivorship is increased in
saturated soil with decreasing temperatures (Hoback et al. 2002). So later this
summer, saturated soils could reduce larval populations but don’t count on it
for eggs. <o:p></o:p></span></div>
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<span style="font-family: inherit;"><br /></span></div>
<div class="MsoNormal">
<span style="font-family: inherit;"><span style="line-height: 115%;">T<span style="font-family: inherit;">he bottom line is all these factors had some
impact on overwintering egg mortality. There was probably more egg death this
winter compared to more normal winter temperatures. I do think some corn
rootworm eggs survived in Iowa. In a recent <a href="http://www.extension.iastate.edu/CropNews/2014/0604hodgson.htm" target="_blank">ICM News article</a>, I estimated corn
rootworm egg hatch is happening now if they survived. This prediction is solely based on growing
degree days in the soil. Research has demonstrated about 50% of the eggs hatch
when they accumulate 684-767 degrees (base 52</span></span><span style="font-family: inherit;"><span style="line-height: 115%;">°</span><span style="line-height: 115%;">F, soil). It makes sense that egg hatch starts
in southern Iowa every year, with the average hatching date for the state
around 6 June. Predicted egg hatch is important because larvae will fe<span style="font-family: inherit;">ed on
corn roots for about 3 weeks. I encourage everyone to assess corn root injury
as larvae finish feeding. Remember, one
node of injured roots means a 15% yield loss (Tinsley et al. 2012). It's called the billion dollar pest for a reason!</span></span></span></span></div>
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<span style="font-family: inherit;"><b>Map data courtesy of Iowa
Environmental Mesonet, ISU Department of Agronomy.</b><o:p></o:p></span></div>
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<span style="font-family: inherit;"><b>References</b><o:p></o:p></span></div>
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<span style="font-family: inherit;">Godfrey, L.D., L.J. Meinke, R.J. Wright, and G.L. Hein. 1995.
Environmental and edaphic effects on western corn rootworm overwintering egg
survival. Journal of Economic Entomology 88: 1445-1454.<o:p></o:p></span></div>
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<span style="background: white; color: #333333; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;"><span style="font-family: inherit;">Gray, M.E., and J.J. Tollefson.
1988. Influence of tilla</span>ge systems on egg populations of western and northern
corn rootworms. Journal of the Kansas Entomological Society 61: 186-194.</span><o:p></o:p></div>
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<span style="background: white; color: #333333; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;"><br /></span></div>
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Hoback, W.W., T.L. Clark, L.J. Meinke, L.G. Higley, and J.M.
Scalzitti. 2002. Immersion survival differs among three <i>Diabrotica</i> species. Entomologia Experimentalis et Applicata 105:
29-34.<o:p></o:p></div>
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Tinsley, N.A., R.E. Estes, and M.E. Gray. 2012. Validation
of a nested error component model to estimate damage caused by corn rootworm
larvae. Journal of Applied Entomology 137: 161-169.<o:p></o:p></div>
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Woodson, W.D., and R.D. Gustin. 1993. Low temperature effects
on hatch of western corn rootworm eggs. Journal of the Kansas Entomological
Society 66: 104-107.<o:p></o:p></div>
Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-25873176065371238502014-05-14T19:18:00.001-05:002014-05-14T19:18:33.501-05:00On an aphid huntToday, two special entomologists came to Ames for a short visit: Dr. Dave Voegtlin (Natural History Survey, Champaign, IL) and Dr. Dave Hogg (University of Wisconsin-Madison). Dr. Voegtlin is an aphid taxonomist, aka, he specializes in aphid biology and identification. There are only a few people like him in the world and I really appreciate his expertise and (Canadian) sense of humor. I met with the "Daves," Matt O'Neal (ISU soybean entomologist) and my postdoc, Thelma Heidel-Baker to talk about the state of affairs in the aphid world. It is easy to absorb their energy about aphids and we could have talked for days about emerging research projects.<br />
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The Daves are touring the north central region scouting for soybean aphids. They look at buckthorn every spring and fall. You might be (or should be?) wondering why they were looking for soybean aphid when most of the beans in Iowa aren't planted or haven't emerged yet. They are scouting for aphids on buckthorn, the overwintering host of soybean aphid. Yes, their primary host is a woody shrub commonly found in shelter belts around the north central region. They move to their secondary host, soybean, every summer. Their life cycle is complicated and I won't go into details here, but they want to learn more about their movement between the primary and secondary host.<br />
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<b>Dave Voegtlin explained how he searches for soybean aphid on buckthorn. </b><b>Photo by Thelma Heidel-Baker. </b></div>
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<b>Dave Hogg and Matt O'Neal hoping to find aphids. </b><b>Photo by Thelma Heidel-Baker. </b></div>
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<b>Close-up of buckthorn, note smooth leaves with reduced venation. </b></div>
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<b>Thelma was practicing her photography skills. </b></div>
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Although we spent some of the morning looking around the ISU campus (there is a LOT of buckthorn on campus because there used to be a breeding program!), we did not find any aphids. Sniff sniff. They did find aphids at previous stops before Iowa and I tried using a special camera lens to take close-up photographs.<br />
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<b>Dr. Voegtlin giving me a camera tutorial. It is actually difficult to take pictures of very small animals! Photo by Thelma Heidel-Baker. </b></div>
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<b>My best photo shows a few soybean nymphs on a buckthorn plant. </b></div>
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Seeing these aphids on buckthorn is kinda like seeing a unicorn. I've worked with soybean aphid since 2001 and have NEVER seen spring colonies on buckthorn. So this was a special work day for me - thanks to the Daves for stopping by today!</div>
Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-66110120772803560252014-05-08T14:40:00.002-05:002014-05-08T14:42:01.776-05:00A spider wedding in my lab tomorrow?My technician, Greg, has been rearing a few black widow spiders in my lab for a few months. It all started with an egg sac donated from the Insect Zoo (thanks?). He has an interest in spiders and is the "go to" guy if you need a spider ID. Since I am not a huge fan of spiders, I don't take the time to learn how to identify them or get to know much about them. I will go 5 soybean rows out of the way to avoid an orb-weaving spider in August.<br />
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Why do we care about black widow spiders? The females are considered highly venomous, but human deaths are rare compared to the number of people envenomated. People bitten by a female black widow may have swelling, redness, muscle pain, nausea, headache, and cramping. The venom contains several toxins and in general sounds like a painful experience. The good news is they are predators, and eat insects and pretty much anything that gets caught in their web. There are a few species of black widow in the U.S. and they have a wide distribution in the southern states. It is possible for black widows to live in Iowa, but finding them here is more likely because they were accidentally introduced instead of established.<br />
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Today Greg let me know that a female and male black widow have reached adulthood. It took constant care to feed them (live) flies and clean their cages every week. <span style="text-align: center;">The spiders are not large, with females about 1.5 inches long and 0.25 inches in diameter. Females are shiny black with a classic, red marking on the belly (ventral) side of the abdomen. </span><br />
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<b>Adult, female black widow, <i>Latrodectus mactans</i>. Photo by wiki.</b></div>
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I have to admit, males are not impressive (insert game show sound <a href="https://www.youtube.com/watch?v=1ytCEuuW2_A" target="_blank">here</a>) - smaller, and dull in color. The adult body is about 0.25 inch in diameter.</div>
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<b>Adult, male black widow, <i>Latrodectus mactans</i>. Photo by Center for Invasive Species Research, University of California-Riverside.</b> </div>
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It was hard to take a good picture of the male and female spiders through the plastic rearing chambers in my lab. I didn't feel brave enough to take the lids off and get a close-up. </div>
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<b>Female black widow spider. Note all the dead flies on the bottom of the cage. She is an efficient predator and quickly kills her prey. </b></div>
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Greg is going to put them together in the same cage tomorrow and see if they mate. Can you hear wedding bells? Male spiders are often wary of females because they are potential prey. So they spin a sperm web and put the packet on one of his palps (kinda like short legs used for bringing food to the mouth). The male will attempt to deposit the sperm in the female before becoming dinner!</div>
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<b>I wonder what will happen at the spider wedding tomorrow? </b></div>
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<b>Male is currently in the left cage. </b></div>
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If successfully mated, a female can produce several egg sacs that contain a few hundred eggs. There is a lot of cannibalism with spiderlings, and so not many actually survive very long. Males don't live very long after becoming an adult, but females could live a few years. Sounds like we have a pet spider in the lab...</div>
Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-1901752951771334932014-04-11T17:09:00.000-05:002014-04-11T17:09:13.072-05:00How to read the updated economic threshold table for alfalfa weevil I recently posted an <a href="http://www.extension.iastate.edu/CropNews/2014/0411hodgson.htm" target="_blank">ICM News article</a> about how scouting for alfalfa weevils in southern Iowa. It doesn't take too many accumulated degree days for them to start moving around and laying eggs. If you grow or scout alfalfa, you will likely see any adults that survived the winter moving in southern Iowa now and northern Iowa next week. In the article, I show an updated economic threshold table based on work from John Tooker at Penn State. It has a lot of numbers in it, and at first, looks kinda confusing. In order to make cost-effective treatment decisions for alfalfa weevil management, three things must be known:<br />
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1. <i>what is the expected market value of the hay ($/ton)?</i><br />
2. <i>how much are the control costs ($/acre)?</i><br />
3. <i>how tall are the plants (inches)?</i><br />
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Take that information and plug it into the table below. Well, I guess you have to actually go out to the field and sample larvae before consulting the table! The larvae are often tucked into stems and expanding terminals. Pull at least 30-50 stems from different areas of the field and madly shake them into a 5-gallon bucket to dislodge them.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9_O_nuPfm__6hL5OfZbfKTXhJIaVrm5-wS_ZO43M3ZRySoffGBU-P54nYb0fSVEf0o1p4ZSokIAdbZKM6AEqfRu7obPO5AG-haIuJFiPNK-5IdgB-iVOUdTpCnLkfbyV7WvcmufoFd8qW/s1600/alfalfa+weevil2+Clemson+Univ+USDA+Coop+Ext+Slide+Series+ipmimagesorg.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9_O_nuPfm__6hL5OfZbfKTXhJIaVrm5-wS_ZO43M3ZRySoffGBU-P54nYb0fSVEf0o1p4ZSokIAdbZKM6AEqfRu7obPO5AG-haIuJFiPNK-5IdgB-iVOUdTpCnLkfbyV7WvcmufoFd8qW/s1600/alfalfa+weevil2+Clemson+Univ+USDA+Coop+Ext+Slide+Series+ipmimagesorg.jpg" height="400" width="400" /></a></div>
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<b>Alfalfa larva (top) and adult. Photos by Clemson University, www.ipmimages.org.</b></div>
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<b>Economic threshold of alfalfa weevil, based on the average number of larvae in a 30-stem sample </b>(Originally published by <span style="color: #4f81bd;"><a href="http://ento.psu.edu/extension/factsheets/alfalfa-weevil" target="_blank">JohnTooker, Penn State Extension</a>).</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUDtr5vETGxQbdkSIV0SroDno01snHGfAdK2M5JKkHLdb-mmjJIPI6UTKFIf4kkgFl32sO2a7Jx08ZYan53tje14GhQDAaiuZn5sEb_h-_kLLcnxmA4WPRcqnbz_2gInr4K5B-RMpicEq4/s1600/2014+AW+ET+table+Penn+state.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUDtr5vETGxQbdkSIV0SroDno01snHGfAdK2M5JKkHLdb-mmjJIPI6UTKFIf4kkgFl32sO2a7Jx08ZYan53tje14GhQDAaiuZn5sEb_h-_kLLcnxmA4WPRcqnbz_2gInr4K5B-RMpicEq4/s1600/2014+AW+ET+table+Penn+state.jpg" height="265" width="400" /></a></div>
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In case the table is still confusing, I highlight two examples. <b>Example 1</b> (look at the orange arrows): if you are expecting $260/ton, control costs of $14/acre, and plants are 20 inches tall...the economic threshold would be 40 larvae per 30-stem sample. In other words, if you sample 30 stems and get at least 40 larvae, consider taking some management action to protect tonnage and hay quality. <b>Example 2 </b>(look at the red arrows): if you are expecting $380/ton, control costs of $12/acre, and plants are 28 inches tall...the economic threshold would be 24 larvae per 30-stem sample. In other words, if you sample 30 stems and get at least 24 larvae, consider taking some management action to protect tonnage and hay quality.<br />
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Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-27297029797655011322014-03-28T08:27:00.007-05:002014-03-28T08:27:57.603-05:00Where are corn rootworm eggs right now?I am "all done" with winter and I'm probably not alone. I'm looking forward to buds bursting, better vegetables and sandals. Insect-related questions coming my way have all been focused on cold winter temperatures that could be killing pests. The main pests of concern are corn rootworms (really, what else is there to talk about in Iowa?). I had to do a little digging in old literature, but found some interesting research on survivorship of corn rootworm eggs (the overwintering life stage).<br />
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<b>Western corn rootworm eggs. Photo by Purdue Extension.</b></div>
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In lab tests, Gustin (1981) showed significant egg mortality at soil depths of 3-6 inches with four constant weeks at -7.5 degrees. But I wonder how often those harsh temperatures might happen in the field? Is that where the majority of eggs are even deposited? And even if those temperatures and depths are realistic, rootworms have survived over 50 years in Iowa and must be relatively cold hardy.</div>
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One method for measuring "how cold does it have to be before it kills rootworm eggs" is finding the supercooling point. The supercooling point is defined as the process of lowering the body temperature below its freezing point without becoming solid. I briefly talked about how insects might do this in a previous <a href="http://iowabuglife.blogspot.com/2014/01/how-do-insects-survive-winter.html" target="_blank">article</a>. This lower lethal temperature would be species specific. Western and northern corn rootworm both had a supercooling point of -27 degrees, but most eggs did not hatch if they experience -21.5 degrees (Ellsbury and Lee 2004).<br />
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Gray and Tollefson (1988) examined the differences of four tillage regimes and corn rootworm egg mortality. In the end, egg density wasn't different in fields that experienced no-till, chisel plowing or moldboard plowing. The timing of cultivation (fall or spring) did not matter either. They also looked at egg deposition, or how deep females might be laying eggs. There was a surprising difference between northern corn rootworm and western corn rootworm. Northern corn rootworm eggs tend to be located closer to the soil surface, while over a third of western corn rootworm eggs were found in the lower 4 inches of the soil. Insects that overwinter deeper in the soil may be further insulated from cold air temperatures. </div>
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Some other things that influence corn rootworm egg (and all other soil-dwelling insects) survivorship over the winter include plant residue, snow cover, and soil moisture (Godfrey et al. 1995). Northern corn rootworm tend to handle dry conditions better than the westerns (Ellsbury and Lee 2004).<br />
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<b>High residue in cornfields can protect soil-dwelling insects from extreme cold temperatures. Photo by Lori Abendroth, Iowa State University. </b></div>
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The bottom line is this cold winter probably had a negative impact on corn rootworm eggs. I expect there to be higher egg mortality compared to normal winter temperatures. But egg survival is increased if they are deeper in the soil and if the field had snow cover and residue. Egg sampling is difficult and tedious, and not recommended. But I still encourage root injury assessments this summer; that will be the true test of egg mortality in corn. </div>
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<b>References:</b></div>
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Ellsbury, M. M. and R. E. Lee Jr. 2004. Supercooling and cold hardiness in eggs of western and northern corn rootworms. Entomologia Experimentalis et Applicata 111: 159-163. </div>
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Godfrey, L. D., L. J. Meinke, R. J. Wright, and G. L. Hein. 1995. Environmental adn edaphic effects on the western corn rootworm overwintering egg survival. Journal of Economic Entomology 88: 1445-1454.<br />
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Gray, M. E. and J. J. Tollefson. 1988. Influence of tillage systems on egg populations of western and northern corn rootworms. Journal of the Kansas Entomological Society 61: 186-194.</div>
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Gustin, R. D. 1981. Soil temperature environment of overwintering western corn rootworm eggs. Environmental Entomology 10: 483-487.</div>
Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-21108243030830752502014-02-04T07:41:00.004-06:002014-02-04T07:41:42.093-06:00Learn more about corn rootwormFor those of you who want to understand more about corn rootworm, I encourage you to view a webinar happening later this month. I was lucky enough to be a co-investigator on an educational grant from the USDA-NIFA North Central IPM Program. We gathered entomologists that focus on corn rootworm from land grant universities. Here is what the the speaker lineup looks like:<br />
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<ul>
<li><i>Rootworm biology and behavior</i>, Dr. Joe Spencer, Illinois Natural History Survey</li>
<li><i>Resistance evolution and IRM for rootworm</i>, Dr. Aaron Gassmann, Iowa State University</li>
<li><i>Adult management options</i>, Dr. Lance Meinke, University of Nebraska-Lincoln</li>
<li><i>Larval management options</i>, Dr. Bob Wright, University of Nebraska-Lincoln</li>
<li><i>Decision tree for growers management options</i>, Dr. Ken Ostlie, University of Minnesota</li>
</ul>
<br />
This FREE webinar will be on February 20, 2014 at 1pm (CST) and end at 2:30pm. You can join from anywhere you have a computer/tablet, internet and speakers. Start connecting to the session about five minutes before 1pm. Use this URL <a href="https://connect.unl.edu/r9ra3734mey/" target="_blank">link </a>to enter the meeting, or copy and paste this link:<br />
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<b>https://connect.unl.edu/r9ra3734mey/</b></div>
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Once connected, you will find a login page. You can enter your name, business, etc. and click "enter room." At this point you should be able to make any sound adjustments. You may want to test your computer before February 20 by using this URL <a href="http://www.extension.iastate.edu/testconnect/" target="_blank">link</a>, or copy and paste this link:<br />
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<b>http://www.extension.iastate.edu/testconnect/</b></div>
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Please spread the word about this webinar to your family, friends, clients or co-workers. We don't often get the "big dogs" all in one place, so this is a unique opportunity to hear from the experts. This is the most important corn pest in Iowa right now, and it is important to be proactive in rootworm management.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrCDTx8KG33XOu3842JinXCY87DPbLrM0lbJsQlaFUhyysPsuyGIVCrFgkb3noaKS90i1vDO4yrhu9Uvz_p7YuADcqtlPhPteRdQcmNoxSTUJNSyBxQ17wHsmaIS6EV6GkjLD6ohqfpkSW/s1600/IMG_0988.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrCDTx8KG33XOu3842JinXCY87DPbLrM0lbJsQlaFUhyysPsuyGIVCrFgkb3noaKS90i1vDO4yrhu9Uvz_p7YuADcqtlPhPteRdQcmNoxSTUJNSyBxQ17wHsmaIS6EV6GkjLD6ohqfpkSW/s1600/IMG_0988.jpg" height="266" width="400" /></a></div>
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<b>Learn more about rootworms right from work or home!</b></div>
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<br />Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-81687041203845347322014-01-24T08:36:00.000-06:002014-01-24T08:36:48.008-06:00How do insects survive the winter?<div class="MsoNormal">
We sure have experienced very cold air temperatures and even
colder windchills this winter. I’ve been asked several times “<i>how cold does it have to get to kill insects</i>?”
Perhaps it is important to understand why cold temperatures kill insects. Insects
are unlike mammals and birds because they must generate their own heat (called
<a href="http://en.wikipedia.org/wiki/Ectotherm" target="_blank">ectotherms</a>). Insects die with they are exposed to temperatures below the
melting point of their body fluids. If they want to survive our cold Iowa winters,
they must avoid freezing or tolerate freezing. Over time, insects have developed
several strategies to survive cold temperatures and none of them involve
wearing fleece. <o:p></o:p></div>
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Some insects just move into human structures in the fall and
keep warm until spring. Think about boxelder bugs and multicolored Asian ladybeetles
aggregating on houses every year. Even if they are protected inside, they will
likely die before spring if they don’t get food and water. Some insects also
migrate to warmer climates to avoid freezing. A classic example is monarch butterflies
moving from Canada to Mexico every year. Sounds pretty good about now!<o:p></o:p></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9irdgnECE5AFR-rR7Hcy9Ok4hB105GiegcuqTHIvN5QQ98p3JWLsEs7ylD3yJq53WwD0VN7u3R8-NtbHXXBEu_zkbGAEdtPNbi6WVnRbA25bEpUUtaKrWmT2LiVRBpdoDcoUn1lOoCRmm/s1600/MALB2+Koch.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9irdgnECE5AFR-rR7Hcy9Ok4hB105GiegcuqTHIvN5QQ98p3JWLsEs7ylD3yJq53WwD0VN7u3R8-NtbHXXBEu_zkbGAEdtPNbi6WVnRbA25bEpUUtaKrWmT2LiVRBpdoDcoUn1lOoCRmm/s1600/MALB2+Koch.JPG" height="300" width="400" /></a></div>
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<b>Multicolored Asian ladybeetles mass on structures every fall. </b></div>
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<b>Photos by Robert Koch. </b></div>
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But most of our persistent insects in Iowa have to
overwinter outside, and two strategies have evolved to survive extreme conditions:
freeze avoidance and freeze tolerance. Freeze-avoidant insects keep body fluids
liquid and freeze-tolerant insects can handle the formation of internal ice. Wait
a minute, what? I know…either strategy seems fantastical. <o:p></o:p></div>
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The main strategy for insects living in the northern
hemisphere, where we have cold temperature for long period of time, is freeze
avoidance. Freeze avoidance can be achieved a few ways. Sometimes insects enter
a “dry” hibernation by getting rid of all the food and water in their body. That way,
ice can’t form inside the body and kill them. Water needs food or dust particles in order to crystallize; water can cool down to -42C without freezing if particles are absent. Other insects have a super waxy
coating on the exoskeleton that protects against ice formation on the body. Amazingly,
some freeze-avoidant insects also produce <a href="http://en.wikipedia.org/wiki/Cryoprotectant" target="_blank">cryoprotectants</a>, such as glycerol and
sugar, to reduce the lethal freezing temperature of the body. So yes, cryoprotectants
act like the antifreeze in your car. I can’t make this stuff up! </div>
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Most insects living in the southern hemisphere, where the
climate is more variable, employ freeze tolerance. These insects can stand ice
formation in the body. Some will actually initiate freezing their body at
relatively high temperatures in order to prepare for a longer hibernation. An example of a freeze-tolerant insect is the woolly bear. [Sidenote: <o:p></o:p>Several <a href="http://en.wikipedia.org/wiki/Pyrrharctia_isabella" target="_blank">winter festivals</a> celebrate the woolly bear kinda like Groundhog's Day.]</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfx6cmSMkOHbYpa-b-ZdISQsq8zjK8ZBH-IQZ9aYdCST_grNYZ_CModgFoM00jFeue5g8xOTLhOebWaO1w1zZuFq_DczKJzD_yGy1JpW9AQ0Mv3MYN2JX-UFZAZcn-iEquAW3IBNt1KON1/s1600/IC_Pyrrharctia_isabella_caterpillar+woolly+bear+wiki.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfx6cmSMkOHbYpa-b-ZdISQsq8zjK8ZBH-IQZ9aYdCST_grNYZ_CModgFoM00jFeue5g8xOTLhOebWaO1w1zZuFq_DczKJzD_yGy1JpW9AQ0Mv3MYN2JX-UFZAZcn-iEquAW3IBNt1KON1/s1600/IC_Pyrrharctia_isabella_caterpillar+woolly+bear+wiki.JPG" height="267" width="400" /></a></div>
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<b>Woolly bears overwinter as cold-hardy caterpillars. </b></div>
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<b>Photo by IronChris, Wiki. </b></div>
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No matter the overwintering strategy, all insects will
eventually die if it gets cold enough. However, the lower lethal temperature is
different for each species. Insects can overwinter in any life stage - some are
belowground and some aboveground. It gets complicated quickly, and so I will
save that for another time. </div>
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Find out more about how insects survive the winter from this <a href="http://en.wikipedia.org/wiki/Insect_winter_ecology" target="_blank">Wiki page</a>.</div>
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Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-82213522400565421802013-08-22T10:51:00.002-05:002013-08-22T10:51:22.017-05:00Soybean aphid spray day completeYesterday my lab finished another successful soybean aphid insecticide spray day. We have evaluated insecticide efficacy to soybean aphid since 2005. I didn't get involved with the program until I started at ISU in 2009, but it's a growing research trial and the largest in the nation. I evaluate a range of products, different chemistries, new formulations, etc. I also compare seed treatments and host plant resistance to foliar insecticides. My program also monitors for genetic resistance to our management tools. Eventually, I expect soybean aphid will develop resistance to pyrethroids and organophosphates, so I want to monitor their response to exposure over time.<br />
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<b>Wearing Tyvek for hours is not my favorite thing to do!</b></div>
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This year, we have 35 treatments at the Northeast Research Farm near Nashua and 15 treatments at the Northwest Research Farm near Sutherland. We sprayed at Nashua yesterday and will spray at Sutherland tomorrow. Aphid numbers have been steadily climbing, with populations doubling every 5-7 days. Many commercial fields have reached the economic threshold, and foliar insecticides are going on all over northern Iowa. Typically late-planted fields have higher soybean aphid numbers - so those fields should be your scouting priority.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWnRWmqaaYPa-hzLIqK1fr46hIs3hDPiMmS8zQRuD6lGSmQ4972Omm38_QWlDz3GsQQ-h6hVxLsX973gCKGJpVkaSx2y9xMrYe2jGY1kDM-Zy0c_C5goxLPMbqiHyW8uHlWV-60qqS9ZN4/s1600/IMG_1010.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWnRWmqaaYPa-hzLIqK1fr46hIs3hDPiMmS8zQRuD6lGSmQ4972Omm38_QWlDz3GsQQ-h6hVxLsX973gCKGJpVkaSx2y9xMrYe2jGY1kDM-Zy0c_C5goxLPMbqiHyW8uHlWV-60qqS9ZN4/s400/IMG_1010.JPG" width="400" /></a></div>
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<b>The spray crew is ready to go with proper PPE! Thanks Greg, Tyler, Eric, Cody K., Cody S. and Mike!</b></div>
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If you are interested in how insecticides perform, I summarize all the results in an annual publication called the Yellow Book. You can access a free copies by year on my <a href="http://www.ent.iastate.edu/dept/faculty/hodgson/extension" target="_blank">website</a>. The 2013 version will be ready for distribution by November.Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-78209075335271247212013-08-14T09:48:00.001-05:002013-08-15T14:28:31.187-05:00Meet my lab!It's about time I talk about humans for once on the blog and not just focus on insects. I wanted to give some big props to the people in my lab that spend all day (every day) outside looking for insects in corn and soybean. My lab has actually grown quite a bit this year and branching out of my usual research comfort zone.<br />
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<b>Some of the lab (L-R): Thelma, Greg, Amanda, Eric, Erin, Ezra, Taylor, Tyler, Sarah and Cody. Yes, I am wearing a cockroach t-shirt!</b></div>
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Greg Van Nostrand is my lab technician and makes sure the work gets done<br />
Hometown: Vincent, Iowa<br />
Major: B.S. Entomology, ISU (2009)<br />
Sports and Hobbies: retro/classic video games<br />
What else? has wanted to be an entomologist since he was a kid; likes Windows, Android, classic rock and energy drinks<br />
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Thelma Heidel-Baker is a new post-doc in my lab. She is working with pollinators in addition to helping me with extension projects<br />
Hometown: Random Lake, Wisconsin<br />
Major: Ph.D. Entomology, University of Minnesota (2012)<br />
Sports and Hobbies: running and more running, triathlons, photography, traveling, and gardening<br />
What else? she has a 4-month old daughter, Ava<br />
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Eric Clifton just recently finished his M.S. degree at ISU and is now working on a Ph.D.<br />
Hometown: Gurnee, Illinois [home to Six Flags Great America]<br />
Major: M.S. Entomology, ISU (2013); Ph.D. Entomology, ISU (2016?)<br />
Sports and Hobbies: frisbee golf, mushroom hunting, dancing, foosball, cross country running, photography, hiking<br />
What else? he believes everyone should watch Billy Murray movies, travel often and eat more tacos to vastly improve quality of life<br />
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*******<br />
Amanda is a new undergraduate working with Thelma this summer<br />
Hometown: Muscatine, Iowa<br />
Major: Biology, expected graduation in 2014<br />
Sports and Hobbies: music, biking, reading<br />
What else? wants to get a M.S. degree in teaching and teach high school biology<br />
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Cody is a new undergraduate working with Greg this summer<br />
Hometown: Maquoketa, Iowa<br />
Major: Environmental Science, expected graduation in 2014<br />
Sports and Hobbies: running, basketball, fishing, hunting, camping and anything outdoors<br />
What else? wants to get a graduate degree and go into research<br />
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Ezra is a new undergraduate working with Thelma this summer<br />
Hometown: Tucson, Arizona<br />
Major: History, expected graduation in 2013<br />
Sports and Hobbies: soccer and football<br />
What else? thinking about graduate school in entomology [bonus!]<br />
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Hailey is a new undergraduate working with Greg this summer<br />
Hometown: Urbandale, Iowa<br />
Major: Biology and Accounting, expected graduation in 2015<br />
Sports and Hobbies: softball, camping, fishing, playing with animals<br />
What else? loves ice cream and her favorite color is blue<br />
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Joe is a new undergraduate working with Thelma this summer<br />
Hometown: Ankeny, Iowa<br />
Major: History, expected graduation in 2013<br />
Sports and Hobbies: golf and tennis<br />
What else? after college, he wants to move to Oregon or Washington<br />
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Kiley is a new undergraduate working with Eric this summer<br />
Hometown: Buffalo, Minnesota<br />
Major: Forestry, expected graduation in 2013<br />
Sports and Hobbies: brewing tea, tying shoelaces and the pursuit of adventure<br />
What else? she wants to breed a bevy of homing pigeons to help communication in southern Canada<br />
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Sarah is a new undergraduate working with Eric this summer<br />
Hometown: Belleville, Illinois<br />
Major: Animal Ecology and Biology, expected graduation in 2014<br />
Sports and Hobbies: photography, watching baseball, and visiting classic car museums<br />
What else? she is allergic to oranges<br />
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Sydney is a new undergraduate working with Greg this summer<br />
Hometown: Pleasantville, Iowa<br />
Major: Biology, expected graduation in 2014<br />
Sports and Hobbies: hiking, photography, hanging with friends, traveling and dog (Winston)<br />
What else? wants to get a graduate degree and conduct field research as a wildlife biologist<br />
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Taylor has been working for us since 2012; she is working with Greg again this summer<br />
Hometown: Sioux City, Iowa<br />
Major: Animal Science, expected graduation in 2015<br />
Sports and Hobbies: movies, swimming, fishing, hiking<br />
What else? aphids are awesome! [obvious brown-nosing attempt, but that is the correct answer!]<br />
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Tyler has been working for use since 2012; he is doing an independent study in grapes this summer<br />
Hometown: Williamsburg, Iowa<br />
Major: Horticulture (Fruit Production), expected graduation in 2014<br />
Sports and Hobbies: hockey, trap shooting, golf, disc golf, boating, bonfires<br />
What else? after college, he hopes to own his own vineyard in the midwest and make beer and wineErin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-13979125380924803282013-08-14T09:43:00.003-05:002013-08-14T09:43:47.430-05:00Aphid numbers quickly building in Iowa - try Speed Scouting!In a recent <a href="http://www.extension.iastate.edu/CropNews/2013/0813hodgson.htm" target="_blank">ICM News article</a>, I reviewed scouting and management tactics for aphids in field crops. They seem to be popping up in Iowa corn and soybean, especially in the northern counties. Soybean aphid populations are doubling every few days in my small plot efficacy evaluation trial at the ISU Northeast Research Farm. Populations will likely exceed the economic threshold of 250 per plant next week and we plan to make our foliar applications when that happens. It always raises a red flag to me when most plants within a field have some soybean aphid - even just a couple on most plants. A week of favorable temperatures can allow them to have exponential growth. We also know that soybean aphids generate more winged adults after soybean bloom and are highly mobile short and long distances.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxyw4mwrWHqofTL5i2rxA_mSXipZLIkQCqGe0Ujy3YirfTzKiGnCc5YlWUcwhtQJIXwyD3xOn2p94qcRa6HnIQ6aRmHkgSCR_-_xYi9631ozByWsB1JeYxTwHdKOct5MT6hnoUzxbfddXo/s1600/full+leaf.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxyw4mwrWHqofTL5i2rxA_mSXipZLIkQCqGe0Ujy3YirfTzKiGnCc5YlWUcwhtQJIXwyD3xOn2p94qcRa6HnIQ6aRmHkgSCR_-_xYi9631ozByWsB1JeYxTwHdKOct5MT6hnoUzxbfddXo/s400/full+leaf.jpg" width="400" /></a></div>
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<b>Now is the time for soybean aphid. Turn over leaves and estimate aphids per plant.</b> </div>
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Have you ever tried Speed Scouting to make treatment decisions for soybean aphid? In an area with lots of soybean aphid, this sampling method can greatly reduce the amount of time it takes to decide if an application is needed. I've got blank Speed Scouting forms available <a href="http://www.ent.iastate.edu/dept/faculty/hodgson/files/ul/2009%20Speed%20Scouting%20blank%20form.pdf" target="_blank">here</a>. Or you can take a look at a blank form below.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWj_A6ZZ7tFc8VBwQ9lsZQG-mlGWUZmQKQO0IQvfZQWhm5P7_lMLv-9r-RSeGH1pR-zaHfezy5Zj0U-g93W5u2hZ2892u-4FgLizqKf9Y9rENvFPQCYDzfUQ5pXySgYSKH3o7VgapKnBxw/s1600/2009+Speed+Scouting+blank+form.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="308" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWj_A6ZZ7tFc8VBwQ9lsZQG-mlGWUZmQKQO0IQvfZQWhm5P7_lMLv-9r-RSeGH1pR-zaHfezy5Zj0U-g93W5u2hZ2892u-4FgLizqKf9Y9rENvFPQCYDzfUQ5pXySgYSKH3o7VgapKnBxw/s400/2009+Speed+Scouting+blank+form.jpg" width="400" /></a></div>
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It's easy to use and most importantly can save a lot of time (hence the name!). You only have to count to 40. Once you get to 40 - stop and consider that plant infested. Look at 11 plants to get started and then use the decision matrix to get the sampling decision. Most of time you will know if you should treat or not in less than 15 minutes.<br />
<br />Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-67477469995266196302013-08-05T09:13:00.001-05:002013-08-05T09:13:42.647-05:00Learn how to identify Japanese beetle femalesRecently, I had a crop consultant ask me to verify his male/female specimens of Japanese beetle. He squished them to look for eggs (which is highly diagnostic of a female!). I thought there might be an easier and less messy way to determine the sex. But after spending some time online and reading through my textbooks, I only found a few external characteristics that were different. I was somewhat disappointed because sometimes beetles have drastically body features. When males and females of the same species look different - that is called <a href="https://en.wikipedia.org/wiki/Sexual_dimorphism" target="_blank">sexual dimorphism</a>.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjY7sfJTbJnEmIks5yUY3jwsOprop0t9nIdPlwRehjS4sUZ_MgrtVXGsxU1f2cIRpSUR-6CGxGyMgeb-o_zH2wtxfWXQ0TlBllVYf2v2BFrwXoyTnWWXR7Mb92g9HIUH2GRESBOcL0KO2S5/s1600/hercules+beetle+alex+wild.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjY7sfJTbJnEmIks5yUY3jwsOprop0t9nIdPlwRehjS4sUZ_MgrtVXGsxU1f2cIRpSUR-6CGxGyMgeb-o_zH2wtxfWXQ0TlBllVYf2v2BFrwXoyTnWWXR7Mb92g9HIUH2GRESBOcL0KO2S5/s400/hercules+beetle+alex+wild.jpg" width="400" /></a></div>
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<b>Western hercules beetles on ash; note male horn on top and size difference. Photo by <a href="http://www.alexanderwild.com/" target="_blank">Alex Wild</a>. </b></div>
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Depending on how good your eyesight is, you will be able to tell male from female Japanese beetle. Look at the first pair of legs and focus on the tibia. The tibia is the late large segment before the tarsus, or "feet." You may need a hand lens to see the tibia. The male will have spikes on the tibia and the female will have more spoon-like paddles. </div>
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<b>Male Japanese beetle. Photo by Tom Hillyer. </b></div>
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<b>Female Japanese beetle. Photo by Tom Hillyer.</b> </div>
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<b>Or just use the squish test to look for eggs in female Japanese beetle. Photo by Tom Hillyer. </b></div>
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For more information (with drawings), visit these websites: <a href="https://utextension.tennessee.edu/publications/Documents/PB946.pdf" target="_blank">University of Tennessee Extension</a> and <a href="http://www.nappfast.org/pest%20reports/popillia_japonica.pdf" target="_blank">NAPPFAST</a>. </div>
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<br />Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-42250348917409035682013-08-02T14:04:00.002-05:002013-08-02T22:17:11.386-05:00Thinking about treating corn rootworm adults? Read this first. Adult corn rootworm emergence is in full swing all around Iowa. Actually seeing adults is a good reminder to <a href="http://www.extension.iastate.edu/CropNews/2013/0731hodgsongassman.htm" target="_blank">assess for larval injury</a> before too much root regrowth obscures feeding. Questions about adult management are popping up from ISU field agronomists, crop consultants, and farmers. My answer is not automatic - it really depends on the field history and ultimate goal for long-term production. Ask yourself:<br />
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<b>#1. Are adults interfering with pollination? </b>Adults aren't considered an economically important life stage unless they clip silks and prevent pollination. The late planting of many fields this year is coinciding with adult emergence. Silk feeding is certainly happening around Iowa. They are strongly attracted to green silks and will "chase" silks in neighboring fields. Target late-planted or late-maturing hybrids for your scouting efforts. After pollination is complete, they will feed on corn leaves, but that is considered minimal.<br />
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Consider a foliar treatment if: 5 or more beetles per ear AND silks have been clipped to less than 1/2 inch AND pollination is not complete. The threshold of 5 beetles is for drought-stressed corn; the threshold can be increased to 15 beetles per ear for fields with adequate moisture. Also keep in mind other silk feeders that may interfering with pollination (e.g., Japanese beetle, corn earworm, etc.).<br />
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<b>Corn rootworm prefer to eat corn silks. Photo by John Obermeyer, Purdue University Extension. </b></div>
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<b>#2. Is pollination complete? </b>If the goal is try and reduce the egg deposition and potential larval damage the next season, then my response gets a little more complicated. First determine if action should be taken by estimating adult density. If scouting reveals 1-2 beetles per plant in continuous corn, it is recommended to take some sort of action; see the table below for more specific numbers. Taking action means targeting adults this year or larvae at planting the following year.<br />
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To try and do an effective job of adult control requires an intense scouting effort and well-timed foliar treatments. We must understand adult emergence in order to apply insecticides to gravid females (mated and mature eggs). Plan for at least two applications, about 7-10 days apart.<br />
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To estimate more specifically, a biofix is established and is defined as the first adult found in that field. After reaching the biofix, emergence of the remaining population is based on accumulating air temperature (i.e., degree days). Calculating accumulating degree days is easy = [(max daily temp + min daily temp)/2]- 53 (lower developmental threshold). So for example, if the maximum temp for the day was 95 and the minimum temp was 50, the calculation would look like this: [(95 + 50)/2] - 53 = 19.5.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQnDB3vT-U0BpfoRupks7-QEq7LOgASz5QYfLP5cQ44i7XlMH6zX5TFQzgkj4ZZoyo4k7age2SWcGPL54BVZb-xIEcVxt_52RV15GIxCSjfxZCAk1RIO7iYABIymLL_j7ZH7AONoYfEfbS/s1600/adult+CRW+DD+example.TIF" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="273" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQnDB3vT-U0BpfoRupks7-QEq7LOgASz5QYfLP5cQ44i7XlMH6zX5TFQzgkj4ZZoyo4k7age2SWcGPL54BVZb-xIEcVxt_52RV15GIxCSjfxZCAk1RIO7iYABIymLL_j7ZH7AONoYfEfbS/s400/adult+CRW+DD+example.TIF" width="400" /></a></div>
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To answer how long adults will emerge depends on the temperatures following the biofix. Warmer days will mean adults emerge faster. It could happen in three weeks or be extended to five weeks during a cooler summer. ISU entomologists studied how long it takes for adult corn rootworm to emerge and in general: males emerge first and westerns develop faster than northerns. Here is a table that more specifically summarizes emergence based on degree days following the biofix:<br />
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<b>#3. How do you know when females are gravid? </b>Again, targeting applications to gravid females is critical. But first you have to distinguish the males from the females. Females are typically larger and have three distinct, black lines on the forewings. Males have a smudgy, black marking on the forewings. See if you can spot the male in the photo above. Gravid females will have swollen abdomens that extend past the end of the forewings. Or consider a looking for mature eggs by expressing them from the abdomen. </div>
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<b>Use the "squish" test to look for mature eggs. Photo by Purdue University Extension. </b></div>
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<b>#4. What are the long-term management goals?</b> If larval root injury is evident and adults are abundant, that should be concerning no matter what management strategy (or strategies) is implemented. Larval root pruning will reduce yield and make plants unstable. I strongly encourage diversifying management to avoid increasing activity during the next growing season. Plus, resistance to Cry3Bb1 and mCry3A is confirmed in Iowa and is a real threat to Iowa's corn production. We need to be more strategic on how we use this technology in order to prolong the efficacy.<br />
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Crop rotation is the single, most effective suppression tool. Corn rootworm larvae will not eat soybean (or other non-corn hosts), and starvation is eminent. I've summarized other management ideas in a <a href="http://www.ent.iastate.edu/dept/faculty/hodgson/files/ul/CRW%20management%202012%20final.pdf" target="_blank">publication </a>with ISU corn entomologist Aaron Gassmann - read it and pass it on!<br />
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Sorry so long, but this is a complicated topic. Hope it helps, ErinErin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-5138542707446100012013-07-12T14:22:00.001-05:002013-07-12T14:22:18.480-05:00Corn silk feeders are worth scouting right nowI saw my first corn tassels of the season and it got me thinking about silk feeders out and about now. But then again, I saw some corn that was only 18 inches tall and looked a long way from tasseling. It's been a crazy summer!<br />
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Of course many of you are noticing Japanese beetles flying around (and maybe hitting your windshields) this week. They are definitely attracted to green silks and can interfere with pollination. Japanese beetles mate and feed in groups. It is not uncommon to see them aggregated on plants, especially along the edge rows. They are highly migratory and are constantly moving around the landscape. Adults have a wide host range (>300 plants) and are likely to find something they like to eat.<br />
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There has been a lot of marketing about controlling Japanese beetles this year. I don't think it is wise to treat for adults BEFORE tasseling. I have preliminary research that shows foliar insecticides do not have a long residual, regardless of the chemistry. Most broad spectrum insecticides will kill adults if the droplets make contact on the body. That application won't have a 7-day residual for immigrating beetles.<br />
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But if beetles are actively feeding when silks are present, determine densities to make smart treatment decisions. Consider an insecticide if: 3 or more beetles per ear AND silks have been clipped to less than an inch AND pollination is not complete. Again, do not expect a long residual with any product, so continue to scout until pollination is over. If a second spray is warranted, alternate chemistries to reduce the chance of developing resistance.<br />
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The tricky part of managing this pest is if you have sweet corn that may have staggered planting dates or late-maturing hybrids. This summer is a good example of field corn at various growth stages, too. Be aware beetles will continue to move to green silks throughout the summer.<br />
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<b>Japanese beetles at the ISU Johnson Research Farm in 2012. </b></div>
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The second most common type of silk feeder is adult corn rootworm. Emergence has started in southern Iowa and it won't be too long before we see them all over the state. Like Japanese beetle, they are strongly attracted to green silks and like to feed and mate in masses. Silk feeding can interfere with pollination, so it is important to scout during this period to ensure kernel formation later this summer. Consider an insecticide if: 5 or more beetles per ear AND silks have been clipped to less than an inch AND pollination is not complete. The threshold can be bumped up to 15 per plant if the field is under adequate moisture conditions.<br />
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<b>Adult corn rootworm can clip silks. Photo by John Obermeyer, Purdue University.</b></div>
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Grasshopper nymphs and adults can also occasionally eat corn silks. They are usually found around field borders first and then can infest the field interior later in the summer. Since grasshoppers are so mobile, it is very difficult to try and estimate densities. So as with the Japanese beetle and corn rootworm, it is important to watch for silk clipping and take action if they are interfering with pollination. Because grasshoppers tend to move short distances and attack border rows first, a border treatment may be a cost effective decision. </div>
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<b>The differential grasshopper is common in Iowa field crops. Photo by David Cappaert, www.ipmimages.org.</b></div>
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The fourth potential corn silk feeder in Iowa is the corn earworm. The larvae have highly variable body color, ranging from yellow, to green or orange, or brown and even purple. There are alternating dark and light stripes running the length of the body. Larvae have a textured appearance, with many spines coming out of small bumps. This is unlike black cutworm or fall armyworm that have smooth bodies. </div>
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Female moths deposit eggs on green silks during the night. First instars will feed on silks and eventually move down inside the tip of the ear. Older larvae will destroy developing kernels. Since trying to kill the larvae once inside the ear is almost impossible, I recommend monitoring adults. The University of Illinois has a nice <a href="http://ipm.illinois.edu/fieldcrops/insects/corn_earworm/" target="_blank">website </a>that summarizes how to properly time a foliar treatment for corn earworm, depending on the type of corn grown. </div>
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<b>Corn earworm larvae can feed on silks before they enter the ear to feed on kernels. Photo by Frank Peairs, www.ipmimages.org.</b></div>
Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-24247440541136660122013-07-02T09:18:00.001-05:002013-07-02T09:18:59.812-05:00Lots of Japanese beetle look-alikes out thereBased on a <a href="http://www.extension.iastate.edu/CropNews/2013/0620hodgsonkuntz.htm" target="_blank">soil temperature prediction model</a>, Japanese beetles should be emerging all over Iowa now. We've seen them at nearly all of our ISU Research Farms. Ok, it helps when we use pheromone traps because they are especially attractive. But we like to be able to catch the first adults of the season!<br />
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At the same time these beautiful beetles are moving around, many other close relatives are coming out, too. Japanese beetles and other "scarabs" belong in the beetle family called Scarabaeidae. There are about 30,000 scarabs around the world. Even though they are highly diverse and abundant, they have a couple things in common: stout bodies, clubbed antennae, and many have broad front legs for digging. Some scarabs can be metallic or brightly colored, while others blend into the landscape. Adults can be active during the day or night depending on the species. Because of their relative size and body weight, they are clumsy fliers that move short distances. Some scarabs are scavengers that feed on dung, carrion or decomposing organic materials; others are significant plant pests. The larvae are distinctive because they are ALWAYS in a c-shape and commonly called grubs.<br />
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<b>Grubs are immature scarab beetles. Note they have three pairs of true legs but lack the fleshy abdominal legs commonly seen on caterpillars. Grubs can be white or transparent, and will always be in a c-shape. Photo by David Cappaert, www.ipmimages.org. </b></div>
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With several scarabs emerging at the same time, proper identification can be difficult. Here is a quick review of the most common scarabs out in Iowa right now:<br />
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<b>Japanese beetle:</b> Adults are just over 1/2 inch in length. These scarabs have one generation per year. They are visually distinct because of the metallic green head and bronze forewings that do not fully cover the abdomen. They also have white tufts of hair along the sides of the abdomen. Adults have a wide host range (>300 plants), including roses, fruit and shade trees, grapes, corn and soybean. Japanese beetles skeletonize leaves by feeding between the veins.<br />
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<b>Japanese beetles are metallic, with clubbed antennae and white tufts of hair. Photo by Dorothy E. Pugh. </b></div>
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<b>Japanese beetles aggregate to feed and mate, leaving skeletonized leaves. Photo by Mark Licht. </b></div>
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<b>False Japanese beetle. </b>Sometimes called a sandhill chafer, this species is commonly mistaken for Japanese beetle. They are similar in body shape and size (1/2 inch in length), but is not metallic green and bronze. They can have white hair along the sides of the abdomen, but it is more evenly dispersed instead of in tufts. False Japanese beetles have one generation per year. Adults feed on flowers, fruits and leaves of many plants, but are not considered a field crop pest.<br />
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<b>False Japanese beetles are hairy scarabs, but not metallic. Photo by Marlin E. Rice.</b></div>
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<b>Masked chafers.</b> There are several species of masked chafers in Iowa. These scarabs have one generation per year. Adults are 1/2 inch in length and oval in shape. Body color can range from dark yellow to tan with dark markings on the head. They can have hairy bodies, wings and legs. Masked chafers are not known to be field crop pests in Iowa. </div>
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<b>Northern masked chafers are hairy and tan scarabs. Photo by Mike Reding and Betsy Anderson, www.ipmimages.org. </b></div>
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<b>May/June beetles.</b> There are several scarabs with the common names of May or June beetles. Most have a life cycle that takes 2-4 years. Adults are usually larger (1 inch in length) and oval in shape. Body color ranges from red to brown. Adults feed on a wide variety of plant foliage, but they are not considered field crop pests in Iowa. </div>
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<b>June beetles are attracted to street lights at night. Photo by Steven Katovich, www.ipmimages.org.</b></div>
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Just a few other scarabs that you could find out this summer. None would be considered field crop pests. </div>
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<b>Ten-lined June beetle. Photo by Eugene E. Nelson, www.ipmimages.org.</b></div>
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<b>Little bear. Photo by Whitney Cranshaw. </b></div>
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<b>Bumble flower beetle. Photo by David Cappaert, www.ipmimages.org. </b></div>
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<br />Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-59191081915620011322013-06-14T09:32:00.001-05:002013-06-14T09:32:39.152-05:00Corn rootworm larvae are hungryToday, I put out an<a href="http://www.extension.iastate.edu/CropNews/2013/0614hodgsonsisson.htm" target="_blank"> ICM News</a> article on predicted corn rootworm egg hatch in Iowa. It has a map of the soil degree day accumulation for the year. Entomologists can predict most insect development based on temperature and we estimate about 50% of corn rootworm eggs should hatch between 684-767 soil degree days (base 52F). The Muscatine area is approaching that important benchmark and many other areas in southern Iowa will in the next week. If we continue to have warm days, expect all insect development to speed up quickly.<br />
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<b>Soil degree day accumulation as of 14 June 2013. </b></div>
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This egg hatch prediction is behind the average date of 6 June and <a href="http://www.extension.iastate.edu/CropNews/2012/0521hodgsonsisson.htm" target="_blank">way behind numbers for 2012</a>. People that track egg hatch in Indiana and Illinois also reported delayed egg hatch, due in part to the extreme drought in 2012. Mike Gray, Illinois extension entomologist, said sometimes <a href="http://bulletin.ipm.illinois.edu/?p=1134" target="_blank">females will lay eggs deeper into the soil </a>profile in drought conditions. The delayed corn planting throughout much of Iowa means larvae will have a smaller root system to feed on and potentially damage. I've also had people ask me about saturated soils killing rootworms this year. It is possible to suffocate the larvae, but the eggs probably survived water-logged soil. </div>
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I encourage all you scouts and farmers to check your corn roots mid July to assess any corn rootworm injury. It will help determine the ongoing strategies for this unruly beast. Unexpected corn rootworm is possible with all Bt traits in continuous corn production. To read more about corn rootworm management, read this short <a href="http://www.ent.iastate.edu/dept/faculty/hodgson/files/ul/CRW%20management%202012%20final.pdf" target="_blank">ISU publication </a>Aaron Gassmann and I wrote over the winter. </div>
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Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-69894640326688213662013-06-13T13:04:00.001-05:002013-06-14T08:21:07.599-05:00Aphids in corn?!I saw something new for the first time today - aphids on V4 corn. Actually, my summer crew found them while scouting for early-season pest activity in a small plot trial at the ISU Johnson Farm just south of Ames, Iowa. Nice job scouting today - way to go!<br />
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<b>Meet part of the 2013 crew. </b><b>I hope to post something just about our lab personnel soon. </b></div>
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This find is exceptional for three reasons. First, Iowa corn doesn't always get infested with grain aphids. The overwintering potential in Iowa isn't fully understood, but most people think they have to migrate here from the southern U.S. every year (kinda like potato leafhopper and many other insects). So it can be hit or miss if they land here and establish at all. But grain aphids would rather live on small grains, like wheat sorghum, barely, oats, rye, etc. However, some of these aphids will feed on corn and have been known to build up to extremely high populations after tasseling. There was an <a href="http://www.extension.iastate.edu/CropNews/2011/0820hodgson.htm" target="_blank">corn aphid outbreak</a> in much of northern Iowa in 2011. But finding them in mid-June is very interesting (to an entomologist!).<br />
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The second curious part of finding aphids in corn this early is that all conventional corn contains an insecticidal seed treatment. My general thinking is aphids shouldn't like to feed on that or stick around long enough to produce nymphs. But it wasn't hard to find alates (winged adults) and nymphs in this small plot trial.<br />
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<b>While looking for cutworms and stalk borers, we found aphids instead!</b></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTbPTFf_jMAfzsqT8ibXIdB88XFORtuHMr1SBS57JdDqlq-ZnNy6W32BRCVCU0ncxx49Sdu9JZ3lfiFd0ZjwfVTF6Ak58tb3uM7MnXMYLhpC5p5OCy_4RwS_Y32VVonwsKm_RtM9oumfVS/s1600/IMG_0513+cropped.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiTbPTFf_jMAfzsqT8ibXIdB88XFORtuHMr1SBS57JdDqlq-ZnNy6W32BRCVCU0ncxx49Sdu9JZ3lfiFd0ZjwfVTF6Ak58tb3uM7MnXMYLhpC5p5OCy_4RwS_Y32VVonwsKm_RtM9oumfVS/s400/IMG_0513+cropped.jpg" width="400" /></a></div>
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<b>Alates and first instars were easy to find on V4 corn today. </b></div>
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<b> The alate was gone, but left behind at least four nymphs on this plant. </b></div>
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The third thing that was surprising is I identified them as English grain aphids. Of the many species we can potentially find in Iowa, the two most common species are <a href="http://www.extension.iastate.edu/CropNews/2009/0807hodgson.htm" target="_blank">corn leaf aphid and bird cherry oat aphid</a>. English grains aphids are a little larger than either of them, but not as big as a pea aphid. Adults have dark cornicles (tailpipes on the sides of the abdomen), "knees," and "feet" with a pale cauda (little appendage at the very tip of the abdomen). This species does not alternate between a primary, woody host and secondary perennial host (like with soybean aphid). It is capable of vectoring barley yellow dwarf virus in small grains. It can overwintering on true grasses within the Poaceae family. </div>
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<b>English grain aphid, note the dark knees and feet. Photo by <a href="http://www.rothamsted.ac.uk/insect-survey/STSitobion_avenae.html" target="_blank">Rothamsted Insect Survey</a>.</b></div>
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I should note we didn't see large colonies on any plant. The alates are migrating to these plots and dropping off a few nymphs. We don't know if they will survive or succumb to the insecticidal seed treatment. Of course we are monitoring these plots weekly and I will post an update if they survive. But in general it means that aphids are around in central Iowa. If colonies persist and are allowed to develop over the growing season, it could be significant feeding that results in yield loss. </div>
Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-67989827815722490872013-06-10T12:12:00.000-05:002013-06-10T12:12:34.669-05:00Seeing maggots in your beans?Well, no two summers are the same. This wet spring has caused some fields to have slug problems. Then other fields are now experiencing some seedcorn maggot problems. Crop consultant in southeastern Iowa, Tom Hillyer provided some excellent photos of recent soybean seedling damage.<br />
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I don't have much experience with seedcorn maggot, so I extracted some biology and management recommendations from our former extension entomologist, Marlin Rice. Female seedcorn maggots (true flies) deposit eggs in the soil and larvae feed on organic residue. Decaying organic matter, like manure, is especially attractive to females. Larvae overwinter and will complete development in the spring. First generation larvae will feed on germinating seeds and seedlings, and can possibly kill the plant. Several generations are possible in Iowa, but generally are not an economic concern after stand establishment. </div>
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If you suspect seedcorn maggot, carefully dig in the seed furrow and look for evidence. You may not find any maggots, but could see a few feeding scars, tunneling in the seed or stem, or the entire seed destroyed. But the same type of damage could be caused by wireworms, grubs or cutworms. </div>
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Rescue treatments for seedcorn maggot do not exist. Areas with persistent populations should consider using an insecticidal seed treatment to protect corn and soybean fields the following year. Seed treatments are encouraged when planting into cool, wet soils with manure applications. </div>
Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-17072411301198097842013-05-29T10:49:00.000-05:002013-05-29T10:49:17.163-05:00It's alive!!It's been a long time since my last post! But it's <b>ALIVE </b>again...<br />
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This cool and very wet spring had impacted planting progress and insect development. So the usual field crop suspects haven't started to show up and are especially behind the 2012 emergence schedule. Some of the questions popping up lately have been with soil-dwelling insects and saturated soils. My general thought on this is that eggs can survive in wet soil, but larvae can't for too long. So if they are small and not very mobile (like corn rootworm larvae), they will probably suffocate. Good news if you like to grow corn!<br />
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Cool wet growing conditions in May and June do favor slugs. I wrote up a recent <a href="http://www.extension.iastate.edu/CropNews/2013/0529hodgson.htm" target="_blank">ICM News article </a>today about managing these early-season beasts. Unfortunately, no-till or minimal tillage practices are conducive to slug populations.<br />
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<b>Slugs can destroy corn and soybean seedlings. Photo by Brian Lang, ISU.</b></div>
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I will try to post more regular updates about other emerging pest activity. Send some of your observations and pictures my way. Thanks for your continued interest in my blog!</div>
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<br />Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-1067667021879448692012-10-15T12:26:00.003-05:002012-10-15T12:26:52.920-05:00Live brown marmorated stink bugs in IowaThe first specimen of brown marmorated stink bug (BMSB) in Iowa was confirmed last February in Cedar Rapids. Since then, several other dead BMSB have been confirmed by our ISU Insect Diagnostician, Laura Jesse. Recently, there have been some live detections near Davenport and Bettendorf, Iowa.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidKTEb842LUf3MPLgiH4gjFHlGGgTDa1wMvJCvlEhy2U4SNHu2VIPVY7xqk4sI0XBEiyOnvOajG6KHgH377c_67PVgONQxBd4KrvqUPJzzvWMMNV_Phlw270QdaIJwFpjsD0I01CYsvavP/s1600/IMG_0267.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidKTEb842LUf3MPLgiH4gjFHlGGgTDa1wMvJCvlEhy2U4SNHu2VIPVY7xqk4sI0XBEiyOnvOajG6KHgH377c_67PVgONQxBd4KrvqUPJzzvWMMNV_Phlw270QdaIJwFpjsD0I01CYsvavP/s400/IMG_0267.JPG" width="400" /></a></div>
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<b>Brown marmorated stink bugs have a marbled coloration, and white-banded antennae. Photo by Laura Jesse, ISU. </b></div>
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These stink bugs are established along the east coast for about a decade. They have been migrating westward in the U.S. When they invade a new area, they are typically considered an urban pest. They attempt to overwinter in human structures similar to boxelder bugs and multicolored Asian lady beetle. But they eventually become a pest of fruit and field crops. Adults and nymphs will probe fruit and leaves, causing necrotic spots. BMSB feeding can severely deform soybean, and cause "stay green" along soybean field edges. </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYIbxouZOOIC6V6p9HlSOOsR9C7_pq3WI4u4j9ibgJaSmAH3_s4vMr2sWGdV-eVbl9lrQeyAj134l7dbMibbC6WpRVufk1bNZKmWikq5Ik_1FuBUQkQXJJMqXodIAKtGAJ1fLxvx3LUkFq/s1600/bmsb+soybean+seed+damage2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYIbxouZOOIC6V6p9HlSOOsR9C7_pq3WI4u4j9ibgJaSmAH3_s4vMr2sWGdV-eVbl9lrQeyAj134l7dbMibbC6WpRVufk1bNZKmWikq5Ik_1FuBUQkQXJJMqXodIAKtGAJ1fLxvx3LUkFq/s320/bmsb+soybean+seed+damage2.jpg" width="320" /></a></div>
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<b>Stink bug feeding during the seed fill stage can cause deformation, shrinkage and discoloration in soybean. Photo by Galen Dively, University of Maryland. </b></div>
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At this time, we don't know if BMSB is established in Iowa, or if a few individuals have hitchhiked here. If you suspect BMSB around your home or buildings, submit samples to the ISU Plant and Insect Diagnostic Clinic. Instructions for submitting samples can be found <a href="http://www.ent.iastate.edu/pidc/">here</a>.</div>
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Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-81783504690650923462012-09-26T12:39:00.001-05:002012-09-26T12:39:51.252-05:00Can insects scream?Someone recently asked me if aphids make sounds when approached by predators. I thought it was a really interesting question, and not just because it was about my favorite insect! I am not aware of aphids making noise when threatened, although they do have other defense mechanisms I may share at a later time. But it did get me thinking about insects that can make noise and how sound is generated a few different ways.<br />
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Cicadas probably come to mind as a well-known noise maker. The males can produce sound, sometimes up to 120 decibels - technically loud enough to cause hearing loss in humans! They have a thin membrane on the outer abdominal wall, called a tymbal. As the abdominal muscles contract and relax, it causes the tymbal to click. Cicadas rapidly vibrate the membrane and the sound amplifies in enlarged air chambers in the abdomen. Each species would have it's own "song" to attract females.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixGo3RgJyWcEnfPKj-m_Odf2ba4bl2fkXi26JTL8pWz3cr8qqx-fI3tMm6k3MAktOlS5T-wY-kOroeU1U9PTZhe9x15klPyBqtMhxFDLXckyrnjj-Mz7oLnEWi8aVq6ZKGRYTcbA1E7Q3Z/s1600/periodical+cicada+Jon+Yuschock+ipmimagesorg.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixGo3RgJyWcEnfPKj-m_Odf2ba4bl2fkXi26JTL8pWz3cr8qqx-fI3tMm6k3MAktOlS5T-wY-kOroeU1U9PTZhe9x15klPyBqtMhxFDLXckyrnjj-Mz7oLnEWi8aVq6ZKGRYTcbA1E7Q3Z/s400/periodical+cicada+Jon+Yuschock+ipmimagesorg.jpg" width="275" /></a></div>
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<b>Periodical cicada, <i>www.ipmimages.org.</i></b></div>
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Most insects stridulate, or rub body parts together, to make noise. In most cases, the males stridulate to attract mates. Crickets and katydids have serrated teeth on the edges of their wings that form comb-like structures. They drag the combs against each other to create sound. But they rub the wings so fast that it just sounds like a chirp. Crickets have four types of chirps: a loud calling song to attract females, a quiet courting song when a female is near, an aggressive song to repel other males, and a brief song after mating. Crickets chirp at different rates depending on the species and temperature. The relationship of cricket chirping is also called <a href="http://en.wikipedia.org/wiki/Dolbear%27s_Law">Dolbear's Law</a>.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsZTmohrddpmEZNjCD_freATj_JgQkeM69z_Po93LTbCi9yqsWBEmVD32U32l6-TCm7zxi7o3ulCBrWlu6d0v44kI2dgxddg2VtBygpgI6HnsK0fF0mVW1PJcxevv1Tqj0lpERsoY9Dcuw/s1600/field+cricket+David+Cappaert,+Michigan+State+University+ipmimagesorg.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="288" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsZTmohrddpmEZNjCD_freATj_JgQkeM69z_Po93LTbCi9yqsWBEmVD32U32l6-TCm7zxi7o3ulCBrWlu6d0v44kI2dgxddg2VtBygpgI6HnsK0fF0mVW1PJcxevv1Tqj0lpERsoY9Dcuw/s400/field+cricket+David+Cappaert,+Michigan+State+University+ipmimagesorg.jpg" width="400" /></a></div>
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<b>Field crickets use their wings to create sound. Photo by David Cappaert, Michigan State University, <i>www.ipmimages.org</i>. </b></div>
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Other insects, like grasshoppers and beetles, scrape their legs to make sound. Grasshoppers have stiff peg-like spines on the hind legs that they rub against their wings. Some long-horned grasshoppers will rub their front legs together for their species-specific "songs."<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmyYvNfp_A8EE_lEDesW7dZCAzSXS_KFaixCHYTZZ1Ch3wxevf2b8-XJ73G9SlTQ212V_7Po9UxyJvVn4CPf8j-4E-_1SUIjNSvyPeYhSKi96TKvgBAXxO3mxRZuscpj5WEXBVe7b-LrMB/s1600/striped+grasshopper+slantface+Amphitornus+coloradus+fauske+ndsu.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="326" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmyYvNfp_A8EE_lEDesW7dZCAzSXS_KFaixCHYTZZ1Ch3wxevf2b8-XJ73G9SlTQ212V_7Po9UxyJvVn4CPf8j-4E-_1SUIjNSvyPeYhSKi96TKvgBAXxO3mxRZuscpj5WEXBVe7b-LrMB/s400/striped+grasshopper+slantface+Amphitornus+coloradus+fauske+ndsu.jpg" width="400" /></a></div>
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<b>Striped slant-face grasshopper with stiff spines on the hind leg used for stridulation. Photo by Gerry Fauske, North Dakota State University. </b></div>
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Some insects use their heads or even their mouthparts to make clicking noises. But perhaps the weirdest noise-making insect I discovered was the tiny water boatman. This aquatic insect can "sing" at 99 decibels by rubbing its penis against his abdomen. Don't ask me how scientists thought of researching this idea or how they collected the data.<br />
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<b>The tiny water boatman can generate a very loud sound, </b><i><b>www.bbc.co.uk.</b> </i></div>
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I found a few nice websites that have audio clips of insects making noise. Enjoy!<br />
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Insect Sounds, <a href="http://www.naturesongs.com/insects.html">www.naturesongs.com/insects.html</a>
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Bug Bytes, <a href="http://www.ars.usda.gov/sp2userfiles/person/3559/soundlibrary.html">www.ars.usda.gov/sp2userfiles/person/3559/soundlibrary.html</a><br />
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Songs of Insects, <a href="http://www.musicofnature.org/songsofinsects/index.html">www.musicofnature.org/songsofinsects/index.html</a><br />
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<br />Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-55158997877089227492012-09-14T07:51:00.001-05:002012-09-14T07:51:49.451-05:00Harvest begins!<div class="separator" style="clear: both; text-align: left;">
In 2012, we worked at several ISU Research Farms, including: Northwest, Northeast, Southeast, Southwest, and Johnson Farms. We were working mostly in soybean but also had several corn trials this year. Plots are drying down quickly and we are preparing for the last step in our summer research - harvest! Usually it goes pretty slow for us because we have to stop often to weigh grain in every plot. Some of the farms have automatic scales on the combine - otherwise we have to weigh grain by hand. </div>
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<br />Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-18937897145211860692012-08-29T11:25:00.002-05:002012-08-29T11:25:47.274-05:00Silent Spring: 50 years of raised environmental awarenessToday I am reminded of one the most important books I've ever read. During my first year of grad school, I was encouraged to read <i><a href="http://www.amazon.com/Silent-Spring-Rachel-Carson/dp/0618249060/ref=sr_1_1?ie=UTF8&qid=1346257494&sr=8-1&keywords=silent+spring">Silent Spring</a></i> by Rachel Carson. She was an environmentalist, joining the US Bureau of Fisheries in 1932. I am sure that wasn't easy thing for a woman to do back then! Rachel became a full-time writer in 1949. She wrote several environmentally-themed books about the ocean, but became interested in soil-dwelling animals, too. As Rachel was battling breast cancer, she published <i>Silent Spring</i> in 1962. <div>
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<b>Rachel Carson, 1907-1964</b></div>
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<i>Silent Spring</i> was one of the first books to address some of the negative effects pesticides can have on animals, including humans. She often argued for more "look before we leap" caution to synthetic pesticides. One of the first popular pesticides, <a href="http://en.wikipedia.org/wiki/DDT">DDT</a>, was manufactured by the Swiss in 1939. DDT was used by many around the world, including the US Army to control malaria, typhus, and dengue fever during WWII. </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJm4RS4yYhqz2KOe-HPma2ijB_t3Yzvz0SBz09C3NABS6c3rWaf7ydJbhckD6ACTwqwDBM7C7w7TSbKoYgNKCKhEO73k60kcmLIv7KQfM1Yu8dzZwlBja0-qBVTLvEm15IX1c8FF8XtekK/s1600/ddt+truck.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJm4RS4yYhqz2KOe-HPma2ijB_t3Yzvz0SBz09C3NABS6c3rWaf7ydJbhckD6ACTwqwDBM7C7w7TSbKoYgNKCKhEO73k60kcmLIv7KQfM1Yu8dzZwlBja0-qBVTLvEm15IX1c8FF8XtekK/s400/ddt+truck.jpg" width="318" /></a></div>
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<b>DDT trucks were common to see on the streets in the 1950s. Sometimes kids would run after the trucks to get dusted. </b></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPI4Bd9EsKsLeLICHhy_VVslvHY-whtjDk040b3vm2FBSseViaN9B1BCYBxVxj0oKgxPpKHIKdMk0tdcQN1FQwBt_cjwbq2Kcz4luhZN0rvA52YIffekF4xISoXUyT0KORHzLUx54VbcoW/s1600/George+Silk,+LIFE+photo+archive.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPI4Bd9EsKsLeLICHhy_VVslvHY-whtjDk040b3vm2FBSseViaN9B1BCYBxVxj0oKgxPpKHIKdMk0tdcQN1FQwBt_cjwbq2Kcz4luhZN0rvA52YIffekF4xISoXUyT0KORHzLUx54VbcoW/s400/George+Silk,+LIFE+photo+archive.jpg" width="316" /></a></div>
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<b>To show how harmless DDT dust was to humans, advertisements like this were popular. Model Kay Heffernon with a soda and hot dog on Jones Beach, NY 1948. Photo by George Silk, LIFE photos. </b></div>
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<b>DDT was popular for home use as well to kill nuisance pests. </b></div>
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At the same time of increasing popularity of synthetic pesticides, Rachel was noticing a decline in bird populations. She called pesticide overuse as a "silencing of the birds." In <i>Silent Spring</i>, she outlined how biomagnification concentrated chemicals through the food chain. Although she reviews many case studies in her book, her example of robin decline at Michigan State University was particularly interesting. In the mid 1950s, ornithologist George Wallace discovered dead and dying robins on campus; tests confirmed elevated levels of DDT. He later showed DDT used to control Dutch Elm Disease was takeng up by earthworms that were toxic food for many birds. </div>
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Another example of DDT biomagnification was in the Bald Eagle. By the early 1960s, only about 400 breeding pairs were in the lower 48 states. One suspected cause of decline was egg shell thinning and sterility from DDT. In 1967, Bald Eagles were placed on the Endangered Species List. The US banned DDT in 1972 and the number of breeding pairs has dramatically increased 20-fold. In 2007, the Bald Eagle and other bird species were removed from the Endangered Species List.</div>
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Her books and other publications got mixed reviews from scientists and industry. She testified before congress and called for a "pesticide commission" to help protect human health and the environment. Of the 12 pesticides she mentioned in her book, 8 are now banned and 3 are severely restricted. Rachel raised awareness for the environment and the need for regulation; and in 1970 the EPA was created. She revived many awards for her efforts, including the Presidential Medal of Freedom after her death. Although I do think pesticides have a place for pest control in order for food production and human health, I do agree with Rachel that we should them in more cautiously and with purpose. For more information about Rachel Carson, visit these links:</div>
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<a href="http://www.rachelcarson.org/">http://www.rachelcarson.org/</a>
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<a href="http://en.wikipedia.org/wiki/Rachel_Carson">http://en.wikipedia.org/wiki/Rachel_Carson</a>
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<a href="http://www.pophistorydig.com/?p=11132">http://www.pophistorydig.com/?p=11132</a>
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<a href="http://museum.msu.edu/?q=node/687">http://museum.msu.edu/?q=node/687</a>
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Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0tag:blogger.com,1999:blog-868547576674833700.post-22812269404184048372012-08-20T09:56:00.000-05:002012-08-20T09:56:05.370-05:00Updated bean leaf beetle thresholdsSummer is winding down fast, but some areas in Iowa still have respectable numbers of bean leaf beetle. The second generation is coming out and could cause direct injury to soybean pods. If your beans are still developing, it might be a good time to go out and take some sweeps.<br />
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<b> Bean leaf beetles can be confused with southern corn rootworm and other beetles. Look for four dark spots on the forewings, and a dark triangle behind the "neck." Photo by Marlin E. Rice. </b></div>
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Overwintering and first generation bean leaf beetles rarely cause direct economic damage to soybean in Iowa; plants compensate for defoliation in many ways. But they can transmit bean pod mottle virus that can impact the market value of food grade soybean. Bean leaf beetle can cause direct injury to pods during the seed fill stage depending on when the second generation emerges. </div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaOQ7Y9yjzzAIRQgDc_FTk7-NMM4jlXpOeGZ-yYSGvk7Mn0YSXGOHv7-SySl-Nx_OgRdVxnD5g-sCIarna_WYWwf4vevDp3QDaoQw13JyqAmqCOkKYFXCRXQxKbbyw1ozn3wBarnRk790z/s1600/BeanLeafBeetlePodDamage+licht.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaOQ7Y9yjzzAIRQgDc_FTk7-NMM4jlXpOeGZ-yYSGvk7Mn0YSXGOHv7-SySl-Nx_OgRdVxnD5g-sCIarna_WYWwf4vevDp3QDaoQw13JyqAmqCOkKYFXCRXQxKbbyw1ozn3wBarnRk790z/s400/BeanLeafBeetlePodDamage+licht.JPG" width="300" /></a></div>
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<b>Bean leaf beetles can eat about 0.2 pods per day. Note they don't eat all the way through the pod, like grasshoppers can. Photo by Mark Licht, ISU Extension. </b></div>
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Last year I had several questions about treatment thresholds for bean leaf beetle given our higher market values. With the help of ISU entomology grad student, Mike McCarville, we created a dynamic threshold calculator. It's a downloadable Excel file where you plug in your market value and control costs. Visit this<a href="http://www.extension.iastate.edu/CropNews/2011/0815hodgson.htm"> ICM News article</a> and scroll to the bottom for the link the calculator. To learn more about bean leaf beetle biology and management, click <a href="http://www.ent.iastate.edu/soybeaninsects/bean_leaf_beetle">here</a>.</div>
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Erin Hodgsonhttp://www.blogger.com/profile/00103263384873670334noreply@blogger.com0