Immune interactions, risk assessment and compatibility of the endoparasitoid Cotesia flavipes parasitizing Diatraea saccharalis larvae exposed to two entomopathogenic fungi

[Display omitted] •The tested fungi do not alter the host’s humoral immune system, parasitized or not.•Disturbances on host’s cellular immune system does not influence parasitoid biology.•Larval D. saccharalis is a suitable host for the parasitoid after fungal exposition.•The use of two fungi with C. flavipes is compatible and safe for IPM systems. Using natural enemies for pest control is considered environmentally safe, but risk assessment of the concomitant use of different biological control agents needs deeper investigations. A special attention should be given to interactions between entomopathogenic fungi and parasitoids concomitantly used for sugarcane, once this culture has a remarkable IPM system in Brazil. The exposure of a host to non-lethal entomopathogens may lead to immune modulations potentially harmful for the development of a parasitoid. In this study, we exposed the sugarcane borer larvae to Metarhizium anisopliae and Beauveria bassiana strains, applied in sugarcane fields to manage, respectively, spittlebugs and the sugarcane weevil, but ineffective to kill sugarcane borer larvae, Diatraea saccharalis (Lepidoptera: Crambidae). The selected experimental concentrations of B. bassiana (1.75 × 109 spores), M. anisopliae (1.64 × 109 spores) and a mixture of B. bassiana + M. anisopliae (1.69 × 109 spores) diluted in 0.01% Tween®80 were above field concentrations to expose the insects to an extreme scenario. Eggs of sugarcane borer were exposed to entomopathogens and, at the fifth instar, larvae were parasitized by Cotesia flavipes (Hymenoptera: Braconidae). Measurements of larval humoral and cellular immune responses were made at 5 days after parasitism in larvae exposed or not to the entomopathogenic fungi. Phenoloxidase and lysozyme activities were not altered in D. saccharalis larvae exposed to entomopathogenic fungi or parasitized by C. flavipes. The activity of β-N-acetyl-D-glucosaminidase, total hemocyte count and total protein titer were not altered by entomopathogenic fungi exposition, but were reduced in parasitized larvae. No side effects of entomopathogenic fungi exposition were observed on biological parameters of D. saccharalis or in C. flavipes developing in hosts exposed to entomopathogenic fungi. These results add information on the risk assessment of this interaction and demonstrate the compatibility of concomitant use of these two entomopathogens and the parasitoid C. flavipes for pest management in sugarcane fields.