Compatibility between Entomopathogenic Fungi and Egg Parasitoids (Trichogrammatidae): A Laboratory Study for Their Combined Use to Control Duponchelia fovealis

SIMPLE SUMMARY: The European pepper moth is an important pest of many crops; however, some countries, such as Brazil, do not have insecticides registered for combating this pest. In particular, the egg stage of the biological cycle of this moth is the most difficult life stage to control. In this sense, biological control agents, including egg parasitoids and entomopathogenic fungi, can be an alternative to pesticides. In this study, laboratory tests were conducted to evaluate the susceptibility of two species of egg parasitoids (Trichogrammatidae family) to entomopathogenic fungal strains (including two commercial bioinsecticides). These fungal strains were applied on eggs of the European pepper moth before and after parasitism by the parasitoids. Overall, the entomopathogens reduced the parasitism rate, adult emergence, and longevity of adult parasitoids by less than 30%. The results obtained constitute the first step in designing effective pest control strategies. Future research should investigate the sub-lethal effects of the fungal strains on the parasitoids in the field. ABSTRACT: The European pepper moth, Duponchelia fovealis (Lepidoptera: Crambidae), is a key pest in strawberry production. Entomopathogenic fungi (EF) and parasitoids of the Trichogrammatidae family are effective biological control agents of this pest with the potential to be used jointly for improved efficacy. This study aims to evaluate the susceptibility of Trichogramma atopovirilia and Trichogramma pretiosum to two Beauveria bassiana strains (B2 and B3) and two commercial bioinsecticides (Bovemax(®) and Methamax(®)) by applying them to D. fovealis eggs in pre- and post-parasitism periods. Pre-parasitism application of B2 and B3 did not affect the percentage of D. fovealis eggs parasitized by either Trichogramma species, except in the case of T. atopovirilia when eggs were sprayed with B3 at 1.5 × 10(5) conidia mL(−1) (16.7% less than the control). In contrast, eggs sprayed with 1.5 × 10(8) conidia mL(−1) of the commercial bioinsecticides were not parasitized by any Trichogramma species. Overall, the EF tested reduced the parasitism rate, adult emergence, and longevity of Trichogramma adults by less than 30% in all cases. The adverse effects of the B. bassiana strains and commercial products on the biological traits of both Trichogramma species were minimal, meaning that these agents can be used jointly in D. fovealis control strategies.