Friday, July 27, 2012

In recognition of the 2012 Bradshaw Entomology Lab...

So, it has been another great summer in the lab with another great crew (pictured to the right is everyone but Sean and Kelli). Sure there is plenty of work left to do in order to finish out the season; however, about 1/3 of the lab will be left after most of them go back off to school next month. So, I took the opportunity to take a photo today. I got a bit carried away this year and designed t-shirts for the lab.

There is sort of a Nebraska story and tradition that explains the "entomology blackshirts" shirts that we are wearing. According to Wikipedia, "The Blackshirts are the first-string defensive unit players for the Nebraska Cornhuskers football team." The short of it is that Nebraska football coaches in the 1960s began giving out black shirts to their top defensive teams. It eventually became a tradition where players had to "earn" their black practice shirts and at some point the entire Nebraska football defensive line became popularly known (at least in Nebraska and to all Husker fans) as "Blackshirts". So I felt it apt to hand out my blackshirts about mid-season once the summer crew had earned them. You can see the shirt fronts in the photos. The symbol for the Husker Blackshirts is often a skull and crossbones. Therefore, obviously, the back of the shirts have a screen print of Acherontia lachesis (the death's head hawkmoth, of Silence of the Lambs fame). There are actually three species of Acherontia that are commonly known as death's head moths. However, Acherontia lachesis could be roughly translated from old Greek as "proportioner of pain" and I kind of like the ring of that. This may seem as a bit of an eccentric act; however, a well-rooted team needs a bit of mythology and I have got a rock-solid crew deserving of my gratitude. Go team!

Sunday, July 15, 2012

More sawfly damage...

As indicated in a previous post, 2012 has been a boom year for wheat stem sawfly damage. I decided to put together a short video. I have had a few phone calls to the office inquiring about lodged wheat and some word-of-mouth chatter that would indicate that some wheat producers do not recognize wheat stem sawfly damage. It has been a windy year for a windy part of the country, so apparently a number of producers, understandably, are blaming their lodged wheat on the wind. Some are blaming the lodged wheat on the variety and suggesting that the variety that they planted had poor straw strength (or poorer than expected). This is only part of the story. Because the wheat stem sawfly girdles wheat tillers near the base late in the growing season, it often takes a bit of wind to knock the wheat down. When the wheat finally does fall, it often does so in dramatic fashion. The video is a bit of a crude "Duke Dukem" style view of sawfly damage, but I think it gets the point across.

Friday, July 6, 2012

Inventive students

An undergraduate in my lab developing a device to carry cow dung samples. That's right dung samples. She is working on a project that explores the attraction of dung beetles to various "qualities" of cow dung. She needed a better way of transporting her bait into the field. I've been telling my students this summer that they have unofficial minors in arts & crafts.

Friday, June 22, 2012

Wheat harvest

Time to harvest wheat in the PREC entomology lab. Wheat harvest is perhaps three weeks early this year. It has been a warm year! Riley (undergrad student in the foreground) and Susan (lab tech with a face full of wheat in the background) are hauling in some stems that we will split to evaluate the presence of wheat stem sawflies.

Saturday, May 19, 2012

2012 looks to be a big year for Cephis cinctus

A female wheat stem sawfly resting on wheat awns. (5/15/12)

The wheat stem sawfly, Cephus cinctus, is having a boom year in 2012. This insect is a pest of wheat. The female sawflies (pictured above) deposit a single egg into a wheat stem (a single female sawfly will visit at least 10 wheat stems to deposit her eggs). The larvae that result will feed inside the hollow wheat stem until they are large enough to pupate. At that time the larva will move down the stem and make a pupal chamber near the wheat crown. However, before it develops into a pupa, the larvae will cut the wheat stem a few inches above the pupal chamber. This cutting activity (with the assistance of the wind) will cause the wheat tiller to fall, taking the wheat head and its grain with it to the ground. This year I have had numerous producers and crop scouts commenting on their presence. Locations that normally have infestations are reporting high numbers of sawflies and they are being found in locations where they have not been normally seen before. Unfortunately, there is little that can be done. Chemical control is not effective in their control. We currently do not have high-yielding winter wheat varieties with resistance against this insect. As I've briefly mentioned before, I am on the hunt to locate beneficial insects that might reduce their numbers. I currently have more than 30 wheat fields enrolled in a survey to determine the current distribution of the wheat stem sawfly and the parasitoid wasps that attack it. My lab is collecting as many production practices that we can from the producers that manage these fields. With any luck, I hope to find relationships between production practices and what roll they might play in mitigating sawfly numbers or in improving habitat quality for its natural enemies.

Sunday, April 22, 2012

Dung beetles

A pinned, adult specimen of Phanaeus vindex, the 'rainbow scarab'.
It is one of the more colorful beetles that bury dung to protect and
feed their offspring.
My lab has added poo to our list of "study subjects". Cow poo in particular. My new postdoc, Sean Whipple, has some interesting ideas regarding the role of dung beetles to provide ecosystem services. He recently completed his dung-beetle focused doctorate program at UN-L. Continuing on this work, my lab intends to explore the roles that these diminutive creatures play in such things as restoring carbon and nitrogen back into rangelands and pastures in the Great Plains. Perhaps, more importantly, what can we do in managing our pastures and range to facilitate the activities of dung beetles. The previous work that has been published has indicated that these insects can have tremendous value even in reducing particular greenhouse gases that would otherwise emanate from our rangeland and pastures. As much as ~80% of greenhouse gas emissions have been found to be sequestered by these insects on rangeland. You may these numbers surprising; however, these insects can incorporate dung back into the sod very quickly. In fact, many dung beetle species prefer fresh cattle dung and so they (particularly the dung beetle species that bury their dung or 'brood' balls) move this fresh excrement into the soil very quickly as they compete for this resource.
Some dung beetles are rather striking (e.g., the above specimen of Phanaeus vindex) and we generally think of them as rolling balls of dung across the grasslands. (Many species such as P. vindex take their brood balls directly into the ground, without rolling them around.) However, there are many species (across a couple taxonomic families) of 'dung beetle', some of which would not necessarily strike you as a dung beetle and they can be quite tiny. Nevertheless, even the smallest dung beetles (see video of some small dung beetles in the subfamily Aphodiinae) work to break down feces as the adults and their offspring carve up the resource. This process can also facilitate the entry of fungi that can further break down the dung. There will be much more on this topic appearing here in the near future.

Wednesday, January 4, 2012

Wheat stem sawfly and its parasitoids

I will be discussing this in more detail at next weeks Crop Production Clinics in North Platte and Gering, but I needed to test out a new blog posting scheme. This was as good a reason as any. The image (from left to right) is Cephus cinctus, Bracon cephi and Bracon lissogaster (the parasitoids identifications are pending additional confirmation.