Live brown marmorated stink bugs in Iowa

The 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.

Brown marmorated stink bugs have a marbled coloration, and white-banded antennae. Photo by Laura Jesse, ISU. 

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. 

Stink bug feeding during the seed fill stage can cause deformation, shrinkage and discoloration in soybean. Photo by Galen Dively, University of Maryland. 

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 here.

Can 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.

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.

Periodical cicada, www.ipmimages.org.

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 Dolbear's Law.

Field crickets use their wings to create sound. Photo by David Cappaert, Michigan State University, www.ipmimages.org. 

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."

Striped slant-face grasshopper with stiff spines on the hind leg used for stridulation. Photo by Gerry Fauske, North Dakota State University. 

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.

The tiny water boatman can generate a very loud sound, www.bbc.co.uk. 

I found a few nice websites that have audio clips of insects making noise. Enjoy!

Insect Sounds, www.naturesongs.com/insects.html

Bug Bytes, www.ars.usda.gov/sp2userfiles/person/3559/soundlibrary.html

Songs of Insects, www.musicofnature.org/songsofinsects/index.html

Harvest begins!

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. 

Silent Spring: 50 years of raised environmental awareness

Today 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 Silent Spring 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 Silent Spring in 1962. 

Rachel Carson, 1907-1964

Silent Spring 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, DDT, 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. 

DDT trucks were common to see on the streets in the 1950s. Sometimes kids would run after the trucks to get dusted. 

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. 

DDT was popular for home use as well to kill nuisance pests. 

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 Silent Spring, 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. 

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.

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:

http://www.rachelcarson.org/

http://en.wikipedia.org/wiki/Rachel_Carson

http://www.pophistorydig.com/?p=11132

http://museum.msu.edu/?q=node/687

Updated bean leaf beetle thresholds

Summer 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.

 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. 

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. 

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. 

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 ICM News article and scroll to the bottom for the link the calculator. To learn more about bean leaf beetle biology and management, click here.

2012 Insect Field Clinic a success

Yesterday, I hosted an all-day clinic for insects at FEEL just west of Ames. I don't think there has been an ISU insect-focused field day in over 15 years. I planned a combination of inside and outside presentations and some hands-on demonstrations. There were even 3 guys from Hawaii attending the meeting! I thought you might like to see some photos of the clinic.

Bob Wright, Professor of Entomology at the University of Nebraska-Lincoln, came out and helped with a few of the classes. Photo by Adam Sission, ISU IPM Program.

We reviewed identification and management of common corn and soybean pests. Much of the conversation was around corn rootworm. Photo by Adam Sission, ISU IPM Program.

Everyone got a chance to use Bt tissue testing kits for corn rootworm. These tests are an important first step when visiting potential problem fields in Iowa.  Photo by Adam Sission, ISU IPM Program.

The guys from Hawaii really enjoyed their trip to Iowa. They learned a lot about intensive row crop agriculture!  Photo by Adam Sission, ISU IPM Program.

Big spray day at Nashua

This morning, we sprayed foliar insecticides at the Northeast Research Farm near Nashua, Iowa. This is the nation's largest soybean aphid efficacy evaluation, and it's been building ever since it started in 2005. This year, we had 35 treatments at Nashua and 25 treatments at the Northwest Research Farm near Sutherland. We also have a smaller evaluation for Japanese beetle near Ames.

This year, our soybean aphid counts have been almost non-existent. But we are trying to make lemonade out of our research trials. We've been monitoring for spider mites as well, and will have some updated information on efficacy summaries after harvest. We publish all of our soybean pest evaluations in a Yellow Book and post them online. You can find 2005-2011 Yellow Books on our soybean aphid website.

I thought you might like to see our spray crew in action. Enjoy!

Safety first...my lab is very conscientious about PPE!

 We use a backpack sprayer with a 6-row boom to cover our plots. It takes two people to get the job done. 

It took about 4 hours to get all the plots treated this year. It was great weather to spray this year!

Finding an orange bug in corn?

This week, I had a couple of questions about "orange bugs in corn." I scoured through my reference materials and also on the web. I didn't see anything that quite matched up to the descriptions over the phone. But someone actually sent a picture to me and that really helped. It was none other than the very common boxelder bug! Donald Lewis, ISU Horticulture Entomologist, recently reported exceptionally high numbers of boxelder bugs in Iowa this year. Our warm winter and spring was ideal for boxelder bugs to survive and then boom in numbers.

Boxelder bug adult. Note the red-orange wing margins and red eyes. Photo by Joseph Berger, www.ipmimages.org.

Most people can easily recognize boxelder bug adults in urban areas, particularly on maple and ash trees. But the nymphs are bright orange or red, and can be confused with other insects.

 

Boxelder bug nymphs sort of look like big, red aphids. Eventually the nymphs will develop dark wing pads. Photo by Whitney Cranshaw, www.ipmimages.org.

Boxelder bug nymphs and adults prefer to feed on boxelder seed pods, but they have been found on many different plants this year. They rarely damage ornamental trees and are not a concern to field crops. Sometimes the adults can become nuisance pests in the fall when they try to overwinter in human structures. I suspect they will be an issue this fall based on our summer numbers.

 Here is a mixture of boxelder bug life stages. Photo by William M. Ciesla, Forest Health Management, www.ipmimages.org.

Finding mites or something else in soybean?

This month, I've really stressed the importance of scouting for spider mites in corn and soybean. Some farmers have starting treating both crops for field-wide infestations. Many people don't have a lot of practice looking for this tiny pest (does 1988 ring a bell?). But with a little practice, most people can easily recognize these little specks moving on leaves, especially if accompanied by webbing and leaf discoloration. A hand lens may be required to see the eggs, nymphs and adults if your vision isn't great.

As more people are actually looking for tiny pests, they are noticing other things moving around at the same time. I've had LOTS of questions about these "long, fast moving insects" on soybean leaves in combination with spider mites. I am fairly certain people are seeing thrips [side note: thrips is singular and plural, kinda like moose]. They are fairly common to see every year, with soybean thrips the main species in Iowa. We have predatory thrips and other plant-feeding species here, too. I can try to point out body descriptions to distinguish the two pests.

Mites would be smaller (less than a millimeter or 1/20 inch) than thrips and round. They are light brown in color with two dark spots on the body. Mites are arachnids and are wingless as adults. Mites live in colonies and will produce a dirty webbing on the underside of leaves. In hot temperatures, spider mites can produce >15 overlapping generations each summer. See a previous ICM News article for management recommendations.

  Adult twospotted spider mites have 8 legs and two dark spots on the body. Photo by Frank Peairs, Colorado State University.

Thrips are cigar-shaped insects, ranging from 1-5 millimeters long (up to 1/5 inch). They are varible in color, including dark or light brown, orange and translucent. Adults can have small, fringed wings. Thrips' have unique mouthparts; they rasp (stab) and puncture plant cells then suck up the sap. Thrips can produce 3-4 generations per year. They can be found anywhere on the plant but don't usually form colonies, and are very fast-moving insects. Thrips rarely cause economic damage in Iowa, but their feeding damage can be more noticeable in drought-stressed fields. Consider a foliar insecticide if 75% of leaves show discoloration and there is an average of 8 thrips per leaf. See Purdue University's website for more info.

Soybean thrips adult and nymphs. Photo by John Obermeyer, Purdue University.

Pioneer Field Day

Today I'm at FEEL talking about insects and IPM. Should be a great day for extension!

Is your "spider sense" tingling for mites this year?

Do things seem a little too quite in your fields this summer? Maybe you've been out looking for plant pests, but haven't seen any major activity? I would strongly encourage everyone to get out and start looking for twospotted spider mites in soybean and corn, especially if your fields are under drought stress. Finding spider mites takes a little extra time, but you don't want to wait until it is too late to make a treatment decision.

Twospotted spider mites are often surrounded in webbing as they build colonies. Heavily infested plants look dirty and covered in webs. Look on lower leaves for initial infestations. Photo by David Cappaert, Michigan State University.

Leaves with heavy stippling is an indication spider mites have been feeding for a long time. Eventually the leaves will turn yellow, then die and fall off the plant prematurely. Photo by Whitney Cranshaw, Colorado State University.

Spider mites have many overlapping generations of adults, nymphs and eggs. Photo by Brian Lang, ISU Field Agronomist.

This photo was taken in Richardson County, Nebraska on 6 July 2012 by Tracy Cameron. He has been monitoring this field for over a month. Spider mites have spread throughout this soybean field and caused discoloration and leaf drop. 

Some of you may remember the dreadful summer of 1988, when hot and dry weather ravaged the midwest. Our field crops suffered from a horrible spider mite outbreak and farmers lost a lot of yield. I hope spider mite infestations don't get that bad this year. But it is important to be proactive with this pest and not wait for a field-wide disaster. Read this ICM News article for management information. 

Beetles: here, there and everywhere

Just like the Beatles song said, "Nobody can deny that there's something there." Many of you probably noticed a lot of little shiny black beetles around your home and even out in the field. I've seen a few different beetles actively moving around. The sap beetle, or sometimes called the picnic beetle, can be found in high numbers in urban areas now. As the common name suggests, they are attracted to human food, like fruit and vegetables. But they are normally seen  feeding on overripe fruit and decaying organic matter. In a few weeks you may see them feeding on corn silks. They are also secondary invaders and will feed in corn husks infested by corn earworm. Most literature suggests they aren't an economic pest.

Sap beetles are black and shiny with four irregular spots on the forewings. Note the antennae are clubbed and the wings don't fully cover the abdomen. Photo by Joyce Gross, UC-Berkeley.

In addition, I've got reports of a few different flea beetles in corn. Corn flea beetles are common to see early in the season. Corn is the preferred host plant where the adults scrape along upper and lower corn leaves. They will also feed on grasses. The feeding itself isn't an economic problem, but they can vector a bacteria that causes Stewart's wilt. Foliar insecticides are not economically justified after V5.

Corn flea beetles are small, shiny and black. Note the enlarged hindleg femurs used for jumping. Photo by Mike Quinn, TexasEnto.net.

Another flea beetle out and about lately is the redheaded flea beetle. They are similar in size to the corn flea beetle, but more oval in shape and have a red head (funny how entomologists come up with common names!). They can feed a several weeds, corn and alfalfa.

 

The redheaded flea beetle also has enlarged hindleg femurs for jumping. Photo by Lewis Veith.

Getting creative to collect Japanese beetle

Many of you are talking about the high numbers of Japanese beetles in Iowa this year. They have increased exponentially in some of our small plot trials in central Iowa since last week. The dual-lure pheromone trap from Trece is one way to collect these adults. The lures are extremely attractive to Japanese beetle and can draw in adults from a mile away. So the traps are ideal for first detection in a new area, but not recommended as a management tool.

This Japanese beetle pheromone trap can fill up in about an hour right now in Story County, Iowa. Photo by Brent Pringnitz, Iowa State University.

In case some of you are wanted to see just HOW MANY Japanese beetles you can collect, a regular pheromone trap just won't cut it because it fills up too fast. Well, a few people have taken it to another level to see how many GALLONS they could trap in one day. Rex De Bruin and Chris Sparks at BASF Plant Science in Story County replaced the green collection container with a 13-gallon trash bag. They were able to fill it over night. We've done this in the past to use the beetles for lab assays and it is not a good smell.

This modified Japanese beetle pheromone trap (13-gallon trash bag) was filled overnight. The trap entrance was clogged with more beetles! Photos by Rex De Bruin, BASF.

Japanese beetles are hungry

Since I first mentioned seeing Japanese beetle about two weeks ago, I've had many reports of significant numbers around the state of Iowa. There have been a few look-alikes emerging, too, and a recent ICM News article can help with identification. Of course I have seen them on urban plants, but that is where I would expect to see them in June. I noticed adults feeding in corn, soybean and vineyards this week.

Normally, Japanese beetles feed on corn silks later in the season, but Mark Licht, ISU Field Agronomist, noticed them feeding on the corn leaves. I personally haven't seen this before, but I guess they have to feed on something until the silks come out. I did visit a few farms around Ames today and noticed adults in corn. I don't know if they were feeding or just trying to stay protected from the wind. I also noticed beetles defoliating young soybean. They often aggregate to feed and mate, so individual plants had skeletonized leaves.

Japanese beetles in V8 corn at the ISU Johnson Research Farm. Photos taken 14 June 2010 by Erin Hodgson.

 

Japanese beetle defoliation is often overestimated in soybean. Although some leaves were heavily skeletonized, the overall defoliation on these V2/V3 plants was <1%. Photos taken 13 June 2012 by Erin Hodgson. 

Japanese beetle feeding and mating on grape leaves at a winery in eastern Iowa. Photo taken 13 June 2012 by Erin Hodgson.

Ukrainian farmer visit

Today I gave a short presentation on corn and insect management to a group of Ukrainian farmers.

They are on a tour to learn more about agriculture in the midwest. Mark Licht, ISU Field Agronomist, organized a full day of talks and tours for the group. Roger Elmore, ISU Corn Agronomist, started the day with a review of corn production - a really interesting topic for them! I followed with a brief discussion on how we manage insects in Iowa. They don't have access to GMO's, and they asked lots of questions about our options in corn. European corn borer is the more important pest for them. I think they were surprised by how much a bag of corn could cost! Next Mark was going to review tillage, machinery and general production practices in Iowa and give them a tour of some ISU Research Farms.

It was my third time working with a Ukrainian farmer group. The translators are always great about getting my messages across. They thanked me with a hand-painted plant from the Ukraine!

Insects pick up activity in late May

The last week of May was a busy time for insects. Many people reported seeing insects in corn and soybean. Brian Lang wins the prize for finding the first soybean aphid of 2012. I think he usually finds the first ones, even though the prize is just a "woo hoo" from me. Finding winged aphids and first instars is difficult on VC-V1 soybean, so I always try to look for ants and lady beetles.

Lady beetles, pirate bugs and lacewing larvae find soybean aphid on young soybean and are easier to see than aphids. Photo by Marlin E. Rice.

I saw my first Japanese beetle today near the ISU Library. A few adults were destroying a rose garden as the blooms were trying to open up. I also got a few calls this week about white grubs feeding on corn and soybean roots. We have several white grubs as possible culprits, including annual, true and Japanese beetles. Unfortunately, there are no rescue treatments for actively-feeding grubs in field crops.

 White grubs have three pairs of true legs and are always in a c-shape.  Photo by David Cappaert, Michigan State University.

Many people are sending me great photos showing caterpillar damage in corn. Black cutworm is still actively damaging late-planted corn in some areas, but older corn (>V5) should be big enough avoid clipping. First generation European corn borer and corn earworm larvae can be seen in a few fields. For some reason ECB females are attracted to taller corn, so check those fields first (especially if they are non-Bt hybrids). Various armyworms, cutworms and thistle caterpillar have also been reported at low densities in corn.

Corn earworm caterpillars vary greatly in color, ranging from light green to pink to brown. They have light and dark stripes running length of the body. Photo by Clemson University. 

For more insect activity updates, read this ICM News article. You may be seeing more insects out there and I would appreciate any pictures or reports you may have.

Corn rootworm egg hatch is happening now

Like all insects, corn rootworm matures based on heat. Eggs overwinter and hatch into larvae based on accumulating soil degree days. We can expect about 50% of the population to hatch when 684-767 degree days are reached. Southwestern Iowa is experiencing 50% corn rootworm egg hatch right now. The rest of the state will hit that target in 7-14 depending on future temperatures.

Predicted corn rootworm egg hatch in Iowa for 2012. Click here for current degree day accumulation for corn rootworm. Map courtesy of Iowa Environmental Mesonet, ISU Department of Agronomy.

I strongly encourage you to scout for rootworm damage later this summer, especially in continuous corn fields where populations can be higher. I expect larval establishment to be high this year, so estimating root damage is important for gauging population densities. For more information on the 2012 corn rootworm egg hatch in Iowa, read this ICM News article posted today.

Bean leaf beetles are hungry

In March, I predicted low overwintering mortality based on our mild winter. You may have noticed adults become active in alfalfa starting in April. Some soybean research plots around southern and central Iowa have decent numbers feeding on unifoliates. Read more about early-season management of bean leaf beetle here.

 Soybean can compensate for early-season defoliation by bean leaf beetle. Photo by Erin Hodgson (17 May 2012 near Ames, IA).

Circular-shaped defoliation on leaves is an indicator of bean leaf beetle feeding, even if you don't see the beetles. Photo by Erin Hodgson (17 May 2012 near Ames, IA).