Antennal grooming facilitates courtship performance in a group-living insect, the German cockroach Blattella germanica

Abstract

The antennae of adult male German cockroaches detect a contact sex pheromone embedded in the female’s cuticular lipids. The female pheromone stimulates courtship behavior in males, notably a wing-raising (WR) display. Within aggregations, however, cuticular lipids are disseminated by contact among group members, including nymphs and adults of both sexes, and “contamination” of cockroaches with the cuticular lipids of another stage or sex may interfere with sex discrimination and disrupt courtship. We used behavioral observations, bioassays and chemical analysis to determine how males maintain their sensitivity to sex pheromone in aggregations. Males contaminated with female pheromone displayed lower courtship, because residual female pheromone on their antennae adapted their peripheral sensilla and habituated the central nervous system. Female pheromone that contaminated the male’s antennae also elicited courtship from other non-contaminated males, disrupting their sex discrimination in the group. However, antennal grooming effectively removed female pheromone from males’ antennae and maintained their chemosensory acuity and sexual discrimination among group members. Thus, grooming of the antennae and other sensory appendages is an important strategy to enhance sensory acuity, especially in group-living insects like the German cockroach.