Effects of rain and foot disturbances on pit size and location preference of antlions (Myrmeleon immaculatus).

Abstract

The purpose of this study was to examine how disturbances caused by rain and human foot traffic affect antlion (Myrmeleon immaculatus) pit size and location preference. We assessed this by placing antlions in aquaria one side sheltered and the other side in the open in a greenhouse at University of Michigan Biological Station in Pellston, Michigan with three different treatments: no treatment, foot traffic, and rain. For the foot traffic treatment, we damaged the pits with a sandal, and for rain treatment, we poured water on the pits. We measured pit size and location after 24 hours and conducted three trials. The results of this study showed that antlions constructed pits that were 18.5% and 29.4% larger without disturbance and following foot disturbance respectively than following rain disturbance; this difference was significant. The data further revealed that antlions built significantly fewer pits following rain disturbance because approximately three times more antlions did not build pits following rain disturbance compared to the other treatments. I found that antlions following disturbances had a significantly greater preference to build their pits in shelter than those without disturbances. Lastly, I discovered that significantly more antlions relocated to shelter as trial increased for each treatment except rain. Thus, rain disturbances influence antlions’ pit size, decision to construct pits, and location preference; whereas foot disturbances influence location preference.