Compatibility of Habrobracon hebetor say life stages with entomopathogenic nematodes for management of Plodia interpunctella Hübner

Habrobracon hebetor Say (Hymenoptera: Braconidae) and entomopathogenic nematodes (EPNs) are promising biocontrol agents of Plodia interpunctella Hübner (Lepidoptera: Pyralidae). Previous studies have reported that parasitoid developmental stages may influence compatibility with EPNs. We hypothesized that compatibility would vary with parasitoid stage, EPN species, and application rate. Separate laboratory assays evaluated (i) P. interpunctella mortality following EPN and adult H. hebetor exposure; (ii) H. hebetor progeny production after prior EPN exposure; (iii) completion of larval and pupal development by H. hebetor after EPN exposure; and (iv) EPN reproduction in P. interpunctella larvae previously envenomated by H. hebetor . Selected Steinernema and Heterorhabditis species were evaluated mainly at 4,000 and 8,000 IJs/mL. Integrated EPN– H. hebetor treatments caused 86.43–94.64% mortality at 24 h and 89.29–99.64% at 48 h, with additive interactions. However, EPN exposure reduced the H. hebetor progeny production and completion of larval and pupal development. Only 7.00–38.33% of EPN-exposed H. hebetor larvae completed development to adults compared with 54.57% in the control. Prior H. hebetor envenomation did not significantly affect H. megidis IJ production, but reduced production for S. carpocapsae at both rates (28.64–46.38% of corresponding non-envenomated larvae), H. indica at 4,000 IJs/2 mL (24.88%), and H. georgiana at 8,000 IJs/2 mL (38.14%). These findings indicate that EPNs and H. hebetor may be compatible for combined use against P. interpunctella , although negative effects on parasitoid performance and EPN reproduction indicate that application rate and timing require further optimization before operational use.