Cumulative effects of sex pheromone components in mate recognition of Muscidifurax raptorellus

Abstract

In insects, chemical information is often crucial for mate recognition. The chemical signal may be perceived already from a distance or only at close range, depending on the volatility of the sex pheromone compounds. In many species, close-range mate recognition is mediated by compounds of low volatility that originate from the insects' cuticular lipid layer. The most prominent constituents are usually non-polar hydrocarbons, but other, more polar compounds can be present as well. Upon detection, these lipids can elicit courtship behaviour. We studied mate recognition in the parasitoid wasp Muscidifurax raptorellus Kogan & Legner (Hymenoptera: Pteromalidae). In this species, courtship behaviour starts with bouts of wing fanning (high frequency wing beats while standing or walking). Once the male has mounted the female, he shows stereotypical antennal movements (antennal courtship) that lead to female receptivity signalling and copulation. We investigated the role of chemical compounds for mate recognition by evaluating the reaction of male M. raptorellus towards live conspecifics and dummies treated with whole-body extracts or with extract fractions (non-polar, intermediately polar, and polar compounds) in bioassays. Our results indicate that despite the sex specificity of cuticular hydrocarbon profiles, these compounds alone are not sufficient for mate recognition. Rather, we found that cuticular lipids of all three fractions seem to constitute the mate recognition signal, with a ternary mixture eliciting wing fanning significantly more often than single fractions. Overall, our results suggest that the three lipid fractions contribute cumulatively to the mate recognition signal.

Novel insights into insect chemical communication – an introduction

“…Males of the parasitoid wasp Muscidifurax raptorellus Kogan & Legner (Hymenoptera: Pteromalidae) start their courtship of a potential female mating partner with conspicuous wing fanning behavior. Pokorny et al (2022) tested which fractions of female cuticular extracts can trigger male wing fanning. Interestingly, they discovered that polar as well as non-polar cuticular fractions need to be present for full functionality as the mate recognition signal.…”