Condition-dependent mate choice of a parasitoid wasp in the field

Abstract

Recent studies have emphasized that the choosiness of mate-seeking individuals may differ greatly in response to the size and age of both participants. As haplodiploids, parasitoid wasps provide unusual opportunities for studies of mating preferences, since females can produce male offspring without mating, thus changing the consequences of not mating from the standard diploid model. Few studies of wasp mating systems have examined mating patterns in the field, even though the limited dimensions of laboratory cages may prevent normal search patterns or dispersal ranges and thereby potentially alter mating patterns. We thus investigated several size- and age-related variables that may influence the mate choice behaviour of male and female solitary parasitoid wasps Alabagrus texanus (Cresson) (Braconidae) under both field and confined laboratory conditions. In the field, similar numbers of tethered virgin females (1) mated with the first male visitor, (2) rejected the first but then mated with a subsequent male and (3) did not mate at all. Heavy females mated more often than light ones, but male mating success did not significantly differ with male or female mass. Early-arriving males of intermediate mass (and age) obtained the most matings, but the youngest (1-day-old) and oldest males were all unsuccessful. Age-related variance of females did not play a significant role, since they mated immediately after emergence. However, under highly constrained spatial conditions in the laboratory, several of the previously field-resistant females mated despite the limited number of males present, demonstrating the importance of space in the Alabagrus mating system.