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

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.

Is love in the air or at first sight? Mate finding cues used by sympatric male velvet ants (Hymenoptera: Mutillidae)

“…; Brown et al. ; Itadani & Ueno ). However, these results also indicate that the pheromone is not used for species recognition (Johansson & Jones ).…”

“…; Keeling et al. ; Itadani & Ueno ). In mutillids, Brothers () noted that males kept in a container with a female after mating still approached her but gave up trying to copulate after a few seconds.…”

“…Attractive female bioassay. In many hymenoptera, mated females decrease production of male-attractant pheromones (for reviews see Ayasse et al 2001;Keeling et al 2004;Itadani & Ueno 2014). In mutillids, Brothers (1972) noted that males kept in a container with a female after mating still approached her but gave up trying to copulate after a few seconds.…”

“…; Keeling et al. ; Itadani & Ueno ). In experimentally manipulated conditions, when female pheromones are either removed or drowned out with synthetic chemicals, males are able to use visual cues to locate females but with greatly reduced efficiency (Ayasse et al.…”

“…Within the active search strategy, males can search in nesting areas, at flower patches, or at specific landmarks or flyways (for reviews, see Alcock et al 1978;Ayasse et al 2001). In most species studied, once males begin searching, they follow a chemical gradient of pheromones released by a receptive female to determine her position (Ayasse et al 2001;Keeling et al 2004;Itadani & Ueno 2014). In experimentally manipulated conditions, when female pheromones are either removed or drowned out with synthetic chemicals, males are able to use visual cues to locate females but with greatly reduced efficiency (Ayasse et al 1999;Ostrand et al 1999;Fraberger & Ayasse 2007).…”