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.

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.

Sun spider

A Solifugae (Class Arachnida, order Solifugae [=Solpugida]) from Nebraska.

Solifugae (a.k.a. -- sun spiders, wind scorpions, or camel spiders) are common to the dry places of the world. Western Nebraska is such a place. Even still, I was pleasantly surprised today when a fella from one of the local welding companies brought by the critter above. It was apparently roaming around the welding shop. Yep, 'normal people' might freak out upon someone bringing one of these into their office. An entomologist says, "that is so cool!"

I have seen these before in collections and as 'pets' in terrariums, but I've never had someone bring one in for an identification. Maybe you have already noticed that this animal doesn't look like your every-day spider. It isn't. They do belong to the same class as spiders, Arachnida, but they are in a different order, the Solifugae. There are a couple characteristics that make these critters stand out. The chelicerae are fashioned into a set of vertical pincer-like appendages that hang in from of a small set of eyes. Also, count the legs ... Spiders have 8 (4 pair) legs, but how many do you see here? If you counted 10, you were tricked. The first pair of leg-like appendages are not legs, they are enlarged pedipalps that help the sun spider feel around in the darkness where it prefers to hang out.

Our Nebraskan camel spider is only a couple inches long (not as fancy as some of the giant African solifuges). None-the-less, he is now a resident in an aquarium at the PREC entomology lab. Perhaps I'll provide some video of the critter in action in the near future. Hopefully I have some success in keeping it, I'm not doing such a great job with my Madagascar hissing cockroaches (although major kudos to my technicians for helping keep them limping along). If I'm successful at keeping our 'pet' solifuges alive, it is bound to generate interest in the school groups to whom we often speak. 

A lot of gall...(and lame puns)

I got a call a couple days ago; hornets, bees, flies, and wasps "of all kinds" were descending on someone's burr oak. The caller told me that they were witnessing a phenomenon that they "had never seen before in their life". Entomologists (at least extension entomologists) get these kinds of calls with some regularity. The caller was reporting to me that their neighbor's burr oak tree had millions of kinds of Hymenoptera and Diptera moving about all over the acorns of the tree. 

Back in the lab... We now have a number of things happening; sugar beet harvest, sunflower rating, dry bean host resistance assays, potato harvest, wheat planting... you get the point. Yet, the caller was a little dismayed when I refused to drop everything and make the 20-minute trip out to his property to look at a burr oak full of hornets. After getting a short lecture about how so-'n-so back in the day would drop everything to come out whenever he called and how he, as a farmer, has the luxury of doing what he wants when he wants because he is his own boss, I requested that he bring a branch off of the tree into my office. He then remarked that he couldn't because he had wheat to plant... He also didn't seem to amused when I pointed out the irony of his apparent mantra of "doing what he wants when he wants". But I told him that I would look into it.

Yesterday... One of my two very observant technicians came in to my office and mentioned that he had seen a number of burr oaks in town exhibiting the same phenomenon. He also mentioned that we had a burr oak in the front of the PREC, again in the same situation. So, I grabbed my camera, headed out, and the learning began. I saw the same thing that the caller had described -- wasps and hornets and flies roaming all over the "acorns" on the tree. So I did what any self-respecting entomologist would do and picked one of the "acorns" and licked it. Yep, sweet. I had mentioned to the caller that what he was observing on his burr oak was likely due to an infestation of insects (e.g., aphids or scales) secreting honeydew somewhere on the tree. I was partially correct. 

Yellow jackets frantically combing over cynipid galls on oak.

The investigation revealed that... The "acorns" that were observed, are not acorns at all but galls. These particular galls are produced by the tree around a bud that is infested with a tiny cynipid wasp. The wasp larva develops inside of the gall and as it feeds it secretes a honeydew that eventually oozes its way to the surface of the gall. In the fall of the year (after many of the flower plants in the area have finished blooming) many hornets in particular are attracted to the crystalline sugars on the surface of the green galls. If you split a gall open, inside you will find a single, tiny wasp larva. Apparently,  the hornets and bees do an exemplary job of defending the galls from gall parasitoids (even tinier wasps, sort of like this one) that attack the cynipid larva. In fact, a relatively recent study (I think in eastern Colorado) demonstrated that in areas where hornets and kin are less common, the parasitoids have a higher success rate at attacking the galls; therefore, the burr oaks are likely to succumb to the galling cynipids. 

Once the investigation ended... I contacted the caller. He was pretty anxious to know whether I had come out for a visit. I said that I had not, but that I had found other burr oaks in the area exhibiting the same thing. He was amazed that his situation was not unique and inquired as to what was causing it. I said, "aliens". He gave a half-hearted chuckle to my lame pun and then I went on to explain to him all of the details above. He was (again) amazed the diversity of the insect world and the wonders of nature.

How many hornets do you see in the photo above? Leave your answer as a comment under the link posted in Facebook. (Click on the photo to see an enlarged view.)

Sunflower

An adult sunflower receptacle maggot fly, Strauzia 
longipennis. The larvae feed on the white cork-like
material within the head (or receptacle) of the sunflower.

An adult black blister beetle, Epicauta pensylvanica. 
They pollinate flowers, consume grasshopper eggs as
larvae, can cause blisters if you touch them, and defoliate 
alfalfa. So, are they beneficial or pests?

Possibly a gray seed weevil, Smicronyx sordidus, on the left.
The newly-emerge adults are often found feeding on budbracts. 
They sometimes are destructive to sunflowers. 
There is also an ant (not sure of the species) on
the right. They are often beneficial and this one is feeding 
on some extrafloral nectar.  

A lacewing egg. Lacewings (Chrysopidae), are a 
natural predator of soft-bodied insects. They are 
natural enemies  of a number of soft-bodied insects 
and mites. Sunflowers can make a good substrate 
for egg laying.

I've been thinking a lot about sunflower as of late. Maybe because I recently harvested about an acre of the stuff. I decided to try my hand at a large sunflower insect control trial this summer. Now I'm in the midst of counting seeds for insect damage, taking hundredweights, and measuring yield. Next, we'll be splitting stalks and searching for injury from stalk-boring insects. All of this will be compiled into a year-end report that I will make publicly available either at the end of the year or very early next year. 

I have similar kinds of efforts with other crops (for example, I'm sure I have more acres devoted to sugarbeet research). However, Helianthus annuus is a bit different in that the abundance of insect life that you can find on (or within) just a single plant is pretty impressive. 

This abundance of insect life also places some particular challenges on their management. There are seed-boring and feeding weevils and caterpillars; flies and weevils that just feed on the head (just the bit that holds the seeds, also called the receptacle); caterpillars and leaf beetles that feed on the leaves; weevils and long-horned beetles that feed within the stalk; and scarab and click beetle larvae that feed on the roots. Ok, but these are just the insects that essentially "parasitize" the plant. Sunflowers have large flowers that attract many, many pollinating insects; from honey bees and bumble bees to beeflies and blister beetles and butterflies. In addition to flowers (usually a single, large flower per plant in cultivated sunflower), they also have extrafloral nectaries, particularly around the bud bracts, that provide a meal for beneficial insects such as adult parasitoids and ants. 

It is all of this shared habitat between beneficial insects and pests that make sunflowers (and some other crops as well) so difficult to manage by some conventional methods. Certainly, host plant resistance against the insects that we do not want could be one useful route to go. However, because of the tricky nature of the Helianthus genome, this might take a while. My colleague and friend, Jarrad Prasifka, was recently hired up in Fargo, ND at the Sunflower Research Unit. Perhaps he will come up with a creative solution in the near future. Until then, I'm working on trying to use chemical applications through an IPM program but using products that might allow application before the buds break open and before chemical applications might negatively impact good insects, such as pollinators. I guess we'll see if I'm successful. In the mean time, I've go a lot of sunflower seeds to count and weigh...

A female Argiope aurantia in a potato field.

A male (under side) Argiope aurantial in a potato field.

Argiope aurantia, the garden spider or corn spider, is stirring up some concerns in the panhandle. We seem to have a bumper crop of these critters this year and some people are concerned about their safety with these 8-legged behemoths lurking around. They are pretty striking; the females are black and yellow with long, black legs, and a body about 1/2 inch wide and 1 and 1/2 inches long. If you have arachnophobia, I'm sure that these animals would send you into shock. However, don't panic, they are good critters to have. They are not poisonous to humans or pets, although a large number of them (and their webbing) can make scouting field crops a notably unpleasant experience. However, they are beneficial for (at least) a couple notable reasons: 1) One of their common names is "corn spider" and they can be a frequent occurrence in corn fields around this time of year. In Nebraska, we irrigate quite a few acres of cropland. Many of these acres use overhead irrigation systems. These systems are held up and moved across the land with tires. Tires leave tire tracks that can hold pools of water and these tracks can make great breeding habitats for Culex sp. mosquitoes -- the vectors of West Nile Virus. These mosquitoes can be quite common, particularly in western Nebraska. Although adult garden spiders probably prefer something bigger like grasshoppers, the smaller, immature spiders may help keep those pestiferous mosquitoes down. 2) A quick search on my favorite reference database reveals many, many papers concerning the protein, material properties, and potential application of this species' silk. So, although some of you may cry, "eeek" upon walking up on one of these critters, they may also be giving a lot of benefit to us in return.

We have some research going on in the lab to understand the potential of Trichograma ostrineae (a parasitic wasp) to control the western bean cutworm (a pest of corn and edible dry beans). These are very, very tiny native wasps that like to lay eggs inside of caterpillar eggs. There are other pest insects that they attack as well, such as the European corn borer. I have an intern from UNESP, Brazil that is helping me understand the parasitism efficiency of this parasitoid on corn and edible dry beans. Bellow is a short video I took of the tiny wasps moving about inside of a petri dish containing a corn leaf with western been cutworm eggs on it. The eggs are less than 1mm.