Response of pit-building antlions to repeated unsuccessful encounters with prey

Abstract

Pit-building antlion larvae are sit-and-wait predatory insects that construct conical pits, from which they ambush prey, in sandy soils. We examined the behavioural responses of antlions to the detection of various sized prey, which they were not allowed to capture. We found that antlions responded faster to smaller prey items, probably because larger prey may be considered a source of disturbance rather than a food source. Antlion response time to provided prey decreased after feeding and was negatively correlated with antlion body mass. Both of these results were indicative of a response to prey that depended on both internal and external factors. Pit dimensions increased with time at a constant rate among antlions in the unsuccessful prey capture or fed groups, but at a decelerating rate in the unfed control group. Contrary to our expectation, we could not detect differences in the rate of mass loss between antlions that were unfed and those experiencing unsuccessful prey captures. We also posited that antlions should exploit a specific prey type more efficiently as the number of encounters they had with it increased. However, there was no support for this prediction in our study. Exploring the responses of predators to prey in general, and in light of the conditions characterizing their natural habitat in particular, can improve our understanding of how predators adapt to cope with environmental variability.