Improvement of reproductive performance of Habrobracon hebetor: Consideration of diapausing and non-diapausing larvae of Plodia interpunctella

Abstract

The major obstacle to the adoption of Habrobracon hebetor (Say) (Hymenoptera: Braconidae) for the management of postharvest moth pests is the short duration of the last instar stage of the hosts, which is the preferred stage by the parasitoid for development. It is postulated that mass rearing of the parasitoid on diapausing larvae is possible due to arrested development of the last instar of Pyralid hosts that offers the parasitoid a wider window to paralyze host larvae. Laboratory studies were conducted to evaluate the rearing of H. hebetor on diapausing and non-diapausing larvae of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) at standard environmental conditions. Host mortality of 100% was observed at nearly all larval densities of diapausing larvae but in non-diapausing larvae, the percentage mortality consistently decreased with increase in host density. More progeny of H. hebetor was produced on diapausing larvae than on non-diapausing larvae. Weights of female parasitoid progeny were highest at host density of 10 for diapausing larvae and not significantly different for males. The number of adults from eggs laid by mated female wasps provisioned daily with fresh diapausing larvae up to 5th day was significantly higher than those by parasitoids provisioned with non-diapausing larvae. The maximum number of adults that completed development from eggs laid daily by H. hebetor provisioned with diapausing larvae was on the 3rd day but those provisioned with non-diapausing larvae was on the 5th day. The results from this study show that diapausing larvae of P. interpunctella will be ideal for mass rearing of H. hebetor for the management of Pyralid populations.