D3159: Evaluation of developmental stages of the parasitoid Habrobracon hebetor for interactions with entomopathogenic nematodes

Plodia interpunctella Hübner (Lepidoptera: Pyralidae), an economically important insect pest, infests a wide range of postharvest commodities. Chemical pesticides have been the key pest management tools for this pest. However, these practices have consequences including insecticide resistance and adverse effects on humans, the environment, and non-target organisms. Alternative to chemical insecticides include the use of natural enemies such as parasitoids and entomopathogenic nematodes (EPNs). Applications of parasitoids or entomopathogenic nematodes have provided some protection from P. interpuctella.  In this study, experiments were conducted to investigate the survivability and reproductive efficacy of Habrobracon hebetor Say (Hymenoptera: Braconidae) when the adult or larval parasitoids were combined with EPNs (Steinernema carpocapsae (All), S. rarum (17C+ E), S. riobrave (355), Heterorhabditis indica (Homi), H. megidis (UK211 strain), and H. marelatus (Reyes strain)). The results showed that P. interpunctella larval mortality did not differ significantly when exposed to adult parasitoids alone or in combination with EPNs.  Fewer H. hebetor F1 adults were produced in EPN treatments involving both the parasitoid and EPNs, with the most pronounced decrease found in treatments involving H. indica. Additionally, the sex ratio of the offspring was male biased in EPN treatments. Similarly, exposure of larval H. hebetor to EPN IJs did not significantly affect P. interpunctella larval mortality but did reduce the H. hebetor larvae reaching adulthood, especially in S. rarum (17C+E) treatment. We conclude that further research is needed to integrate EPNs and H. hebetor to effectively control P. interpunctella, focusing on optimizing the application timing and dosage adjustments.