The effect of disturbance on the size of pit construction in Neuroptera.

Abstract

This study investigated the pit-building behavior in the ant lion species, Neuropteran of the subfamily Myrmeleontinae. These ant lions use pits to capture prey. Construction of pits involves costs of both energy and time inputs. Theoretically, those individuals with a pit size that enables them to maximize benefits gained from capturing prey in these pits whereby minimizing costs accrued during pit building will be the most successful individuals. Availability of food, location of other ant lion pits, variation in environmental conditions, and various disturbance events are factors that cause pit size to fall below the optimum pit size. I hypothesized that as the level of pit disturbance increased, the size of subsequent pits would be smaller that initial pit size due to increased time and energy necessary to rebuild pits. I set up three treatments to test the effect of disturbance on pit size: those exposed to low, intermediate, and high levels of disturbance. Analysis of variance showed that there was a significant decrease in volume over time in individuals that were exposed to high levels of disturbance (p=.021). There was also a significant decrease in depth over time (p=.018). In addition, there was no significant difference in pit size observed with the three levels of disturbance. Rather, there was a decrease in pit size during the day (p=.031), with an overall increase in pit size over multiple days. This suggests that individuals are capable of recovering from high levels of disturbance. Inadequate experimental design limited the degree of utilization of data collected, thereby reducing the conclusivity of the hypothesis that increased pit disturbance will result in smaller pit size.