Can bats and spiders help farmers control crop pests?

My name is John Woloschuk, a graduate student pursuing his master's degree in Biology here at BGSU. This is my second year with the department and I have had the fortunate opportunity to work with a talented group of faculty that strives daily to provide knowledge that will improve science. My graduate research is investigating how different types of agricultural ditches and predator characteristics (mobility and energy demand) influence bat and spider activity on farms in Northwest Ohio. More specifically, I want to see if these predators feeding along ditches traverse into adjacent corn fields to take advantage of crop pests. Improved ditches may foster more prey that attracts these predators, and increases predator spillover into adjacent corn fields, thus leading to increased crop-pest reduction.

In order to test my hypotheses, I conducted a series of surveys at 10 different farms throughout this past summer. I recorded bats, counted spiders and captured insects along the ditches, at 100 and 200 meters into adjacent corn fields. This will allow us to understand how active and abundant the predators are at increasing distances into the fields, as well as what prey they may be taking advantage of. In addition to these surveys, we have conducted isotope analysis on wolf and web spiders (collected at all distances) and bat guano collected from barns. Isotopes are useful in that they help ecologists understand what prey communities predators are taking advantage of in an ecosystem. Therefore, isotopes can help us elucidate whether or not bats and spiders are eating crop insects, ditch insects or a combination of both and how this varies with distance from the ditch.

At this point, the results we have come up with are hinting towards highly mobile predators consuming a combination of crop and ditch insects, which is beneficial for farmers. Less mobile and immobile predators appear to capitalize on whatever prey is within their immediate vicinity. However, making any strong conclusions will require further analysis. Up to the present, we only have data from half our samples, and we will not be able to tell if ditch type has any indirect influence on predator spillover until we get the other half of the samples analyzed. Doing so will require external funding as isotope samples must be sent off to a lab that has the proper equipment to conduct the analysis (we have done the necessary preparation work at BGSU, reducing the analysis costs, but external equipment is needed for the final step). Being able to complete this project will advance the science of food web ecology, help us understand the potential for ditch management to reduce crop pests and help us to elucidate the importance of local predators for agriculture. I hope you will consider a contribution to this important research!