Unstad thesis defense April 26 on insects in prairies

Kody Unstad holds a test tube of antifreeze, which he used as a pitfall trap to sample for insects.
Kody Unstad holds a test tube of antifreeze, which he used as a pitfall trap to sample for insects.

Kody Unstad will defend his master's thesis, "Predictors of Insect Diversity and Abundance in a Fragmented Tallgrass Prairie Ecosystem," April 26 at 11 a.m. in Hardin Hall 901. Craig Allen is his adviser.


Despite providing many services, the tallgrass prairie and its ecological community is one of the most endangered ecosystems in North America. Remaining habitat exists as remnants in a highly-fragmented landscape. To make informed conservation decisions we need to better understand the effects of this fragmentation. Using the ecologically important insect groups, ants and ground beetles, this study provides baseline data on the biological diversity of southeast Nebraska prairies and investigates what management, landscape, and habitat characteristics affect them. Pitfall trap sampling was conducted in 23 tallgrass remnants scattered throughout the Southeast Prairies Biologically Unique Landscape in 2010 and 2011. Multi-model inference was used for analysis of the data.

Twenty-eight species of ants were collected with the majority being grassland-obligates. With a positive correlation, model selection results indicate that Shannon diversity of grassland ants is best predicted by the average number of grass species per square meter (m2) while their abundance is positively associated with the amount of nearby haymeadow.

Most ants belonged to the Opportunist and Cold Climate Specialist functional groups. A comparison with prior studies indicates this functional group composition to be most similar to cool-temperate forests. Though different habitats, their cooler climates likely produce this similar composition.

Nineteen species of ground beetles were collected, with two species comprising nearly 95 percent of the collection. These two species are incapable of flight, a physiological factor that may contribute to their high abundances by leaving them hidden from predators. As with grassland ants, the strongest predictor of Shannon diversity for ground beetles was the average number of grass species per m2.

Results suggest that ants and ground beetles are non-randomly distributed in relation to landscape, habitat, and management factors. High abundances of grassland-obligate ants are associated with high amounts of haymeadow suggesting these areas may be a priority for ant conservation. Results also suggest that sites with more grass species sustain more diverse communities of ants and ground beetles, information that can be incorporated into relevant conservation decisions.