Chemically Mediated Mate Finding of the Polyphagous Solitary Parasitoid Itoplectis naranyae (Hymenoptera: Ichneumonidae)

Abstract

Abstract Polyphagous solitary parasitoids have difficulty finding mates that can be widely dispersed because of their polyphagous natures. Males of polyphagous species are more likely to rely on compounds characteristic of the female or on sex pheromones to find mates. However, the mating biology of few polyphagous parasitoids has been studied and sex pheromones are known for only a few species of parasitoids altogether. Here we examined the mating biology of the polyphagous parasitoid Itoplectis naranyae Ashmead (Hymenoptera: Ichneumonidae), which attacks a variety of lepidopteran pupae. The existence and timing of emission of female sex pheromones and male response with age were studied in the laboratory. A field test was also conducted to confirm the attractiveness of newly emerged females to wild males over a distance. The results confirmed that volatile compounds are used in the sexual communication in I. naranyae. Females attracted males most strongly shortly after emergence; pupae and older females were much less attractive. Older (30-d-old) males were most responsive to female sex pheromones. Males with prior experience with females responded more strongly than naïve males. The field test showed that traps containing virgin females attracted wild males. These results showed that this solitary polyphagous species uses volatile compounds to find scattered mates at close and moderate ranges. The existence of chemically mediated mate finding suggests that sex pheromone traps may be useful in management of I. naranyae as a biological control agent.