Controlling infestation of a chocolate factory by Plodia interpunctella by combining mating disruption and the parasitoid Habrobracon hebetor

Assessing the effects of Cry2Aa protein on Habrobracon hebetor (Hymenoptera: Braconidae), a parasitoid of Indian meal moth, Plodia interpunctella (lepidoptera: Pyralidae)

Transgenic crops express Cry proteins exhibit high resistant to target insect pests. When we evaluate the effects of Cry proteins on the parasitoid of target insect pest via tritrophic experiments (transgenic plant-target insect pest-parasitoid) host quality of parasitoids might decrease because of insecticidal protein ingestion, this would cause host-quality mediated effects and influence the accuracy of biosafety assessment. In the current study, high dose of Cry2Aa protein was injected into the hemolymph of Plodia interpunctella by microinjection, and the hemolymph was used as the carrier to deliver Cry protein to Habrobracon hebetor, which has been previously reported as an ectoparasitoid of P. interpunctella larval, in order to avoid the "host-quality mediated effects". Results showed that injected Cry2Aa remained at high concentration and bioactive in the hemolymph of P. interpunctella parasitized by H. hebetor, the hemolymph of P. interpunctella could be used as carriers of Cry protein to H. hebetor, and high dose of Cry2Aa have no negative impacts on the development time, weight of pupa, sex ratio, adults weight (male and female), adult longevity and fecundity, and the activity of stress-related enzymes of H. hebetor. However, the hemolymph of P. interpunctella injected into Galanthus nivalis agglutinin (the positive control) showed significant negative impact on these parameters measured in the present study of H. hebetor. This indicated that Cry2Aa protein had no detrimental effects on the biological parameters of H. hebetor measured in the current study. Meanwhile, this study provides a new method for the safety evaluation of the ectoparasitoids of target pest and might be expanded to the other species of ectoparasitoids of target insects of Cry proteins in biosafety risk assessment.

Habrobracon hebetor and Pteromalus cerealellae as Tools in Post-Harvest Integrated Pest Management

Consumers are increasingly demanding pesticide-free grain/legumes and processed foods. Additionally, there are more restrictions, or complete loss, of insecticides labelled for use in managing stored grain insects in post-harvest ecosystems. Suppression of post-harvest pests using parasitic wasps is a more sustainable alternative than chemical pesticides. Habrobracon hebetor (Say) (Hymenoptera: Braconidae) and Pteromalus cerealellae Ashmead (Hymenoptera: Pteromalidae) are two important parasitoids that limit economically important pests of stored products. Host searching ability and reproductive performances of H. hebetor and P. cerealellae depend on a wide range of factors, such as host species, commodities, and environmental conditions. Further, use of entomopathogens can complement the ability of parasitoids to regulate pest populations. This review provides information on aspects of H. hebetor and P. cerealellae biology and successful regulation of post-harvest pest populations.

Impact of Peanut Depth and Container Size on the Parasitism of Diapausing and Nondiapausing Larvae of Indian Meal Moth (Lepidoptera: Pyralidae) by Habrobracon hebetor (Hymenoptera: Braconidae)

Host mortality and progeny production by the ectoparasitoid, Habrobracon hebetor Say (Hymenoptera: Braconidae) on diapausing and nondiapausing larvae of Plodia interpunctella Hübner (Lepidoptera: Pyralidae) were investigated in response to peanut depths and free space at standard environmental conditions. The free space was created by having four different quantities of peanuts in glass containers of fixed volume or same quantity of peanut in containers of different sizes. Host mortality caused by the parasitoids was significantly higher for diapausing larvae compared with nondiapausing larvae at corresponding peanut depth. Differences in peanut depth affected mortality of nondiapausing larvae exposed to parasitoids but diapausing larvae experienced the same level of mortality. Regardless of container sizes, host mortality was higher than 90.0% for both types of larvae. When equivalent peanut depths were compared, more F1 parasitoids were produced on diapausing larvae than on nondiapausing larvae. Reduced peanut depth affected the sex ratio of parasitoid progeny reared on nondiapausing larvae but not those reared on diapausing larvae. Parasitoid progeny resulting from reduced peanut depth was male-biased and this was more evident with parasitoids that emerged from diapausing host larvae than nondiapausing larvae. Progeny production by H. hebetor was not influenced by container size. This study underscores the fact that host mortality caused by H. hebetor at different peanut depths was significantly different for nondiapausing host larvae, but was not so for diapausing larvae. The container sizes did not affect the performance of H. hebetor in killing P. interpunctella. The entire study emphasizes the potential of diapausing larvae for the rearing of H. hebetor.