Male morphology, performance and female mate choice of a swarming insect

Abstract

Females of many species select mates based on important morphological and performance traits. This behaviour likely facilitates reproductive success thus exhibiting sexual selection. Most such studies have evaluated a single morphological variable, and only a minority of them studies the effects of behaviour and performance (functional capacity: Irschick et al., Evolutionary Ecology Research, 10, 177–196, 2008) at all. This study compares male morphological and performance traits differing in three variables that may correlate with fitness: condition index, flight ascent speed and resistance to torpor in relation to male mating success in the parasitoid wasp species Alabagrus texanus (Braconidae), a species where males swarm about emerging virgin females that display both choosy and non‐choosy behavioural phenotypes. Males that successfully mated with choosy females exhibited higher condition indices and somewhat stronger resistance to torpor than other males. Conversely, males that mated with non‐choosy females did not differ in any trait from other males we measured. Early‐arriving males did not have higher condition indices or greater mating success than other males. Thus, both morphological and performance traits contributed to male success, which acted through female choice, indicating a role for sexual selection. Patterns of choice further differed among females, independent of male traits.