Intimate Rendezvous in a Tritrophic Context? Nothing but the Girls for Male Lysiphlebus testaceipes

Abstract

In insects, mating often occurs after natal dispersal, and hence relies on a coevolved combination of sexual communication and movement allowing mate encounter. Volatile sex pheromones are widespread, generally emitted by females and triggering in‐flight orientation of conspecific males. In parasitoid wasps, unmated females can start laying unfertilized eggs via parthenogenesis so that host patches could serve as sites of rendezvous for mating. Males could therefore use cues associated with host patches to focus their search on females that have successfully found oviposition sites. We hypothesized that in parasitoids exploiting herbivorous hosts, sex pheromones, and herbivore‐induced plant volatiles (HIPV) should act in synergy, triggering male orientation toward ovipositing females. We tested this hypothesis with the aphid parasitoid Lysiphlebus testaceipes. Results from both field and laboratory experiments show that males are strongly attracted to virgin females, but that volatiles from aphid‐infested plants have no effect on male orientation, neither has a cue, nor in interaction with the female sex pheromone. The absence of synergy between sex pheromones and HIPV contrasts with results on other species and raises interesting questions on mating systems and sexual selection in parasitoid wasps.

Sterile males in a parasitoid wasp with complementary sex determination: from fitness costs to population extinction

“…Body size is generally correlated with fitness components, including male ability to find females [ 43 - 45 ]. In the context of sl-CSD, diploid males could be larger than haploid counterparts [ 46 ], and possibly fitter.…”

“…We therefore compared the body size of haploid and diploid males. In V. canescens, as in most other insects, tibia length is correlated with other morphometric measurements [ 47 ] and in fine , with male mating success [ 43 - 45 ]. We therefore used hind tibia length as a proxy.…”

Combined use of herbivore‐induced plant volatiles and sex pheromones for mate location in braconid parasitoids

“…For example, female virgins of the parasitoid Cotesia vestalis are not attracted by host‐induced plant volatiles until they mate (Kugimiya et al ). The male aphid parasitoid, Lysiphlebus testaceipes , are only attracted by conspecific female wasps and not by aphid‐induced plants (Auguste & Fauvergue ). In the gregarious parasitoid Cotesia glomerata , more than half of newly‐emerged female wasps leave their natal patch without mating with siblings, but nevertheless, most female wasps find mates and produced both female and male offspring in the field (Gu & Dorn ).…”