Effects of different host species on the life history of Bracon hebetor

Abstract

Bracon hebetor(Hymenoptera: Braconidae) is a generalist idiobiont ecto-parasitoid that parasitizes a wide range of Lepidoptera and even some phylogenically distant weevil species (Coleoptera; Curculionidae). In the present context, our aim is to find the most suitable host for efficient laboratory rearing ofB. hebetor. We compared fitness traits of this parasitoid wasp on five host species, four species belonging to the Lepidoptera, viz.Galleria mellonella(Pyralidae),Helicoverpa armigeraandSpodoptera litura(Noctuidae),Sitotroga cerealella(Gelechiidae), and one to the Coleoptera, the alfalfa weevilHypera postica(Curculionidae). We determined the parasitic potential, paralysis, daily oviposition rate, development time, total adult progeny, sex ratio and survival. Fecundity was followed during five consecutive days and oviposition period was determined, all under laboratory conditions. The best results were obtained on the wax moth larvae (G. mellonella) for whichB. hebetorproved the highest biological activity in term of paralysis, parasitism and oviposition as compared to other tested host species. InGalleria mellonella, total eggs laid per female per five days and egg-adult survivorship were higher and sex ratio was highly biased toward females, as compared toHypera postica. Intermediate biological activities were found onHelicoverpa armigera,Spodoptera lituraandSitotroga cerealella. These contrasting results show that the plasticity of this species could also represent an important fitness cost difference in performance, which is discussed in terms of phylogenetic distance of the host species (particularly Pyralidae). In conclusion, the possible application of these results can be used in the economically important field of biological control and improve storage of products affected by insect pests.