Bee yard visit and maybe the best day of the summer

Today 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...

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.

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.

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.

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!

Bee suits aren't very flattering, but I felt protected with the cool head gear!

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.

The colorful boxes hold honey bee colonies. Each tower has it's own queen, workers, and drones.

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.

Andy lightly smokes the super before pulling out the frames. I almost sound like I know what I am talking about!

Andy typically only wears the hat with mesh veil. Obviously, he's been working with bees for a long time!

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. 

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. 

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!

Entrance hole for foraging bees. Workers live for a few weeks after emerging from capped cells. 

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!

Maggots and armyworms

It 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!

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).

Seedcorn maggot and pupae at the base of an emerging soybean plant. Photos by Brian Lang, ISU. 

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 earlier prediction for high mortality this year. 

Yellowstriped armyworm. Photo by Tom Hillyer.

Armyworm. Photo by Tom Hillyer.

Bean leaf beetle. Photo by Tom Hillyer. 

Did this winter kill all the corn rootworm eggs?

Insect mortality happens every winter, even under ideal conditions. However, this winter was the 9th coldest in 121 years 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.

Cold temperatures can kill rootworm eggs; temperatures below 18.5°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 blog summary 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 top 12ʺ of the soil in central Iowa and likely other places throughout the state. 

Soil temperature data courtesy of Iowa Environmental Mesonet, ISU Department of Agronomy.

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.

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).

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.

The 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 ICM News article, 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°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 feed 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!

Map data courtesy of Iowa Environmental Mesonet, ISU Department of Agronomy.

References

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.

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.

Hoback, W.W., T.L. Clark, L.J. Meinke, L.G. Higley, and J.M. Scalzitti. 2002. Immersion survival differs among three Diabrotica species. Entomologia Experimentalis et Applicata 105: 29-34.

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.

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.

On an aphid hunt

Today, 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.

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.

Dave Voegtlin explained how he searches for soybean aphid on buckthorn. Photo by Thelma Heidel-Baker. 

Dave Hogg and Matt O'Neal hoping to find aphids. Photo by Thelma Heidel-Baker. 

Close-up of buckthorn, note smooth leaves with reduced venation. 

Thelma was practicing her photography skills. 

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.

Dr. Voegtlin giving me a camera tutorial. It is actually difficult to take pictures of very small animals! Photo by Thelma Heidel-Baker. 

My best photo shows a few soybean nymphs on a buckthorn plant. 

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!

A 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.

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.

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. 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. 

Adult, female black widow, Latrodectus mactans. Photo by wiki.

I have to admit, males are not impressive (insert game show sound here) - smaller, and dull in color. The adult body is about 0.25 inch in diameter.

Adult, male black widow, Latrodectus mactans. Photo by Center for Invasive Species Research, University of California-Riverside. 

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. 

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. 

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!

I wonder what will happen at the spider wedding tomorrow? 

Male is currently in the left cage. 

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...

How to read the updated economic threshold table for alfalfa weevil

I recently posted an ICM News article 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:

1. what is the expected market value of the hay ($/ton)?
2. how much are the control costs ($/acre)?
3. how tall are the plants (inches)?

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.

Alfalfa larva (top) and adult. Photos by Clemson University, www.ipmimages.org.

Economic threshold of alfalfa weevil, based on the average number of larvae in a 30-stem sample (Originally published by JohnTooker, Penn State Extension).

In case the table is still confusing, I highlight two examples. Example 1 (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. Example 2 (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.

Where 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).

Western corn rootworm eggs. Photo by Purdue Extension.

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.

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 article. 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).

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. 

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).

High residue in cornfields can protect soil-dwelling insects from extreme cold temperatures. Photo by Lori Abendroth, Iowa State University. 

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. 

References:

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. 

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.

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.

Gustin, R. D. 1981. Soil temperature environment of overwintering western corn rootworm eggs. Environmental Entomology 10: 483-487.

Learn more about corn rootworm

For 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:

• Rootworm biology and behavior, Dr. Joe Spencer, Illinois Natural History Survey
• Resistance evolution and IRM for rootworm, Dr. Aaron Gassmann, Iowa State University
• Adult management options, Dr. Lance Meinke, University of Nebraska-Lincoln
• Larval management options, Dr. Bob Wright, University of Nebraska-Lincoln
• Decision tree for growers management options, Dr. Ken Ostlie, University of Minnesota

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 link to enter the meeting, or copy and paste this link:

https://connect.unl.edu/r9ra3734mey/

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 link, or copy and paste this link:

http://www.extension.iastate.edu/testconnect/

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.

Learn more about rootworms right from work or home!

How do insects survive the winter?

We sure have experienced very cold air temperatures and even colder windchills this winter. I’ve been asked several times “how cold does it have to get to kill insects?” 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 ectotherms). 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.

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!

Multicolored Asian ladybeetles mass on structures every fall. 

Photos by Robert Koch. 

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.

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 cryoprotectants, 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! 

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: Several winter festivals celebrate the woolly bear kinda like Groundhog's Day.]

Woolly bears overwinter as cold-hardy caterpillars. 

Photo by IronChris, Wiki. 

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. 

Find out more about how insects survive the winter from this Wiki page.

Soybean aphid spray day complete

Yesterday 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.

Wearing Tyvek for hours is not my favorite thing to do!

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.

The spray crew is ready to go with proper PPE! Thanks Greg, Tyler, Eric, Cody K., Cody S. and Mike!

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 website. The 2013 version will be ready for distribution by November.

Meet 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.

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!

Greg Van Nostrand is my lab technician and makes sure the work gets done
Hometown: Vincent, Iowa
Major: B.S. Entomology, ISU (2009)
Sports and Hobbies: retro/classic video games
What else? has wanted to be an entomologist since he was a kid; likes Windows, Android, classic rock and energy drinks

Thelma Heidel-Baker is a new post-doc in my lab. She is working with pollinators in addition to helping me with extension projects
Hometown: Random Lake, Wisconsin
Major: Ph.D. Entomology, University of Minnesota (2012)
Sports and Hobbies: running and more running, triathlons, photography, traveling, and gardening
What else? she has a 4-month old daughter, Ava

Eric Clifton just recently finished his M.S. degree at ISU and is now working on a Ph.D.
Hometown: Gurnee, Illinois [home to Six Flags Great America]
Major: M.S. Entomology, ISU (2013); Ph.D. Entomology, ISU (2016?)
Sports and Hobbies: frisbee golf, mushroom hunting, dancing, foosball, cross country running, photography, hiking
What else? he believes everyone should watch Billy Murray movies, travel often and eat more tacos to vastly improve quality of life

*******
Amanda is a new undergraduate working with Thelma this summer
Hometown: Muscatine, Iowa
Major: Biology, expected graduation in 2014
Sports and Hobbies: music, biking, reading
What else? wants to get a M.S. degree in teaching and teach high school biology

Cody is a new undergraduate working with Greg this summer
Hometown: Maquoketa, Iowa
Major: Environmental Science, expected graduation in 2014
Sports and Hobbies: running, basketball, fishing, hunting, camping and anything outdoors
What else? wants to get a graduate degree and go into research

Ezra is a new undergraduate working with Thelma this summer
Hometown: Tucson, Arizona
Major: History, expected graduation in 2013
Sports and Hobbies: soccer and football
What else? thinking about graduate school in entomology [bonus!]

Hailey is a new undergraduate working with Greg this summer
Hometown: Urbandale, Iowa
Major: Biology and Accounting, expected graduation in 2015
Sports and Hobbies: softball, camping, fishing, playing with animals
What else? loves ice cream and her favorite color is blue

Joe is a new undergraduate working with Thelma this summer
Hometown: Ankeny, Iowa
Major: History, expected graduation in 2013
Sports and Hobbies: golf and tennis
What else? after college, he wants to move to Oregon or Washington

Kiley is a new undergraduate working with Eric this summer
Hometown: Buffalo, Minnesota
Major: Forestry, expected graduation in 2013
Sports and Hobbies: brewing tea, tying shoelaces and the pursuit of adventure
What else? she wants to breed a bevy of homing pigeons to help communication in southern Canada

Sarah is a new undergraduate working with Eric this summer
Hometown: Belleville, Illinois
Major: Animal Ecology and Biology, expected graduation in 2014
Sports and Hobbies: photography, watching baseball, and visiting classic car museums
What else? she is allergic to oranges

Sydney is a new undergraduate working with Greg this summer
Hometown: Pleasantville, Iowa
Major: Biology, expected graduation in 2014
Sports and Hobbies: hiking, photography, hanging with friends, traveling and dog (Winston)
What else? wants to get a graduate degree and conduct field research as a wildlife biologist

Taylor has been working for us since 2012; she is working with Greg again this summer
Hometown: Sioux City, Iowa
Major: Animal Science, expected graduation in 2015
Sports and Hobbies: movies, swimming, fishing, hiking
What else? aphids are awesome! [obvious brown-nosing attempt, but that is the correct answer!]

Tyler has been working for use since 2012; he is doing an independent study in grapes this summer
Hometown: Williamsburg, Iowa
Major: Horticulture (Fruit Production), expected graduation in 2014
Sports and Hobbies: hockey, trap shooting, golf, disc golf, boating, bonfires
What else? after college, he hopes to own his own vineyard in the midwest and make beer and wine

Aphid numbers quickly building in Iowa - try Speed Scouting!

In a recent ICM News article, 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.

Now is the time for soybean aphid. Turn over leaves and estimate aphids per plant. 

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 here. Or you can take a look at a blank form below.

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.

Learn how to identify Japanese beetle females

Recently, 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 sexual dimorphism.

Western hercules beetles on ash; note male horn on top and size difference. Photo by Alex Wild. 

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. 

Male Japanese beetle. Photo by Tom Hillyer. 

Female Japanese beetle. Photo by Tom Hillyer. 

Or just use the squish test to look for eggs in female Japanese beetle. Photo by Tom Hillyer. 

For more information (with drawings), visit these websites: University of Tennessee Extension and NAPPFAST. 

Thinking 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 assess for larval injury 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:

#1. Are adults interfering with pollination? 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.

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.).

Corn rootworm prefer to eat corn silks. Photo by John Obermeyer, Purdue University Extension. 

#2. Is pollination complete? 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.

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.

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.

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:

#3. How do you know when females are gravid? 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. 

Use the "squish" test to look for mature eggs. Photo by Purdue University Extension. 

#4. What are the long-term management goals? 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.

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 publication with ISU corn entomologist Aaron Gassmann - read it and pass it on!

Sorry so long, but this is a complicated topic. Hope it helps, Erin