The Influence of Starvation and Predators on the Mating Behavior of a Semiaquatic Insect

Abstract

Few experimental studies of mating behavior have examined mating behavior shifts in response to ecological factors (e.g., predators, starvation). We conducted experiments designed to: (1) examine multiple trade—doffs between predator avoidance, feeding behavior, and copulating duration in a semiaquatic insect (Microvelia austrina); and (2) address the influence of altered copulation duration on male reproductive success. To examine multiple trade—offs, we used a 2 x 2 factorial design where we measured the amount of time that mating microveliids remained in tandem, for starved and fed microvellids in the presence and absence of predaceous water striders (Gerris remigis). We also looked at the effects of presence vs. absence of green sunfish (Lepomis cyanellus) on microveliid tandem duration. To address the impact of premature pair separation on male mating success, we separated paired microvellids in field populations and measured the time required for each sex to find new mates. To examine the effects of local sex ratio on remating times of males and females, we quantified the sex ratio of field populations via periodic censuses and correlated local sex ratio with remating times. Finally, to address oviposition rates while pairs are in tandem, we measured female oviposition patterns relative to tandem duration for poorly fed and well—fed females. Both Starvation and gerrid presence significantly reduced tandem duration. As a result of male—biased sex ratios, males that prematurely separated from females often faced long search times before securing a new mate. Females oviposited at a constant rate while in tandem. A simple computer simulation incorporating the above observations suggests that reductions in tandem duration can decrease fertilization rates.