Kairomonal Response of the Parasitoid, Bracon hebetor Say, to the Male-Produced Sex Pheromone of Its Host, the Greater Waxmoth, Galleria mellonella (L.)

Abstract

Bracon hebetor is a larval ectoparasitoid that utilizes several pests belonging to the family Pyralidae (Lepidoptera) as hosts. In the present study, we analyzed the kairomonal response of this wasp to the male-produced sex pheromone of a host, the greater wax moth Galleria mellonella, an economically important pest of honeybees, Apis mellifera. Coupled gas chromatography-electroantennographic detection (GC-EAD) revealed three compounds in headspace collections from male G. mellonella that elicited responses from B. hebetor antennae: decanal and the previously identified sex pheromone components, nonanal and undecanal. Y-tube olfactometer tests that used naïve, mated wasps showed that females, but not males, were highly attracted to (a) male G. mellonella headspace samples, (b) two synthetic blends of nonanal and undecanal (in ratios matching that found in male moth samples), and (c) the two aldehydes tested individually. Further, female wasps did not discriminate between a blend of aldehydes and male G. mellonella headspace. In dose-response trials that used octanal, nonanal, decanal, and undecanal, no difference in EAG responses of the two sexes was observed, except for undecanal at the second highest dose, for which female antennae showed significantly larger responses than did male antennae. When the two binary blends were tested at different doses, female wasps were significantly attracted to the two highest doses (1 microg and 10 microg), but not to the lowest dose (100 ng). Our results show that females of this economically important parasitoid utilize the male-produced sex pheromone of a host as an indirect cue to guide them to potential oviposition sites.

Priming of cowpea volatile emissions with defense inducers enhances the plant's attractiveness to parasitoids when attacked by caterpillars

“…showed that the antennae of the parasitoid Microplitis mediator (Haliday) are highly responsive to nonanal released from caterpillar‐damaged cotton plants. Similarly, Cotesia plutellae (Kurdjumov), a parasitoid of the diamondback moth, and the ectoparasitoid Bracon hebetor (Say), which parasitizes mealmoth larvae, show strong electroantennogram (EAG) responses and attraction to nonanal . It should also be noted that nonanal‐baited traps in cotton fields are very attractive to predatory insects such as the anthocorid Orius similis Zheng and the syrphid fly Paragus quadrifasciatus Meigen …”

The Biology and Control of the Greater Wax Moth, Galleria mellonella

“…Dweck et al [87] showed that female B. hebetor utilize the male produced sex pheromone to locate the host, the GWM. Separately, in an attempt to determine the most suitable lepidopteran host for the parasitoid, Ghimire and Phillips [88] reported high oviposition rates but significantly lower parasitoid survival rates on G. mellonella larvae compared with other host species.…”

Beyond sex allocation: the role of mating systems in sexual selection in parasitoid wasps

“…The majority of studies on the use of host kairomones thus far though have focused on females finding oviposition sites. For instance, Habrobracon hebetor females (but not males) are attracted to the sex pheromones produced by males of its host, the greater waxmoth [ Galleria mellonella L. (Pyralidae), Dweck et al , 2010]. One study which did investigate the use of kairomones by males found that in Spalangia cameroni Perkins (Pteromalidae), a solitary parasitoid of house fly pupae, males are attracted to odours produced by suitable hosts and host environment odours (chicken manure; Myint & Walter, 1990).…”