Compatibility of entomopathogenic nematodes with Habrobracon hebetor against Plodia interpunctella

The objectives of this study were to evaluate (i) the virulence of different entomopathogenic nematode (EPN) species to Plodia interpunctella Hübner (Lepidoptera: Pyralidae) larvae and (ii) the direct effects of EPN exposure on Habrobracon hebetor Say (Hymenoptera: Braconidae) larval development. In the virulence bioassay, P. interpunctella larvae were exposed to Steinernema carpocapsae (All), Heterorhabditis megidis (UK211), H. georgiana (Kesha), or Heterorhabditis indica (HOM1) alone or in combination with H. hebetor, and mortality was recorded at 24- and 48-hours post-treatment. Hebrobracon hebetor larvae were exposed to S. carpocapsae (All), S. riobrave (355), S. rarum (17C+E), H. megidis, H. georgiana, or H. indica to understand how EPNs will impact the parasitoid. Two EPN concentrations (4000 and 8000 IJs/mL) were tested in both assays. Results showed that the mortality of P. interpunctella was highest in combined treatments compared to single treatments and control. The combinations of H. georgiana, H. indica, or S. carpocapsae with the parasitoid exceeded 90% mortality of P. interpunctella with the highest being H. georgiana (90.5 ± 2.40). Heterorhabditis megidis consistently showed synergistic interaction with H. hebetor. All tested EPN strains impacted H. hebetor survival, with S. riobrave being the most virulent. in the most H. hebetor survived when combined with H. megidis than with other EPN species. This study suggests that H. megidis has strong potential for integration with H. hebetor to suppress P. interpunctella, as it maintained synergistic effects and caused less disruption to parasitoid development compared to other EPNs.