Medium supplemented with insect pupae powder to induce growth of Beauveria bassiana and Metarhizium robertsii and the pathogenicity of Metarhizium robertsii

The use of insect cuticle is a viable option to induce the growth of entomopatho-genic fungi. Spodoptera frugiperda (Sf) and Heliothis virescens (Hv). Pupal powder was obtained, which was added to enrich the Potato Dextrose Agar (PDA) culture medium at concentrations of 0.25, 0.5 and 1 %. The powder was used to induce the radial growth of Beauveria bassiana and Metarhizium robertsii. The lethal time (TL) ofM. robertsii induced at a concentration of 108 spores/mL and a PDA control. Larval mortality was analyzed by ANO-VA and a Tukey test (alpha = 0.05). The fat content of Sf was 49.9 % and that of Hv 41.9 %; the extract free of nitrogen (ELN) 21.3 and 32.0 %; proteins 15.7 and 13.5 %, and energy 517.87 and 493.73 (Kcal/g), respectively. Nutrients and energy had inducer effect on the growth ofM. robertsii with 1 % Sf and Hv pupal powder, reaching 75.5 and 74.2 mm of radial growth and 60 mm in the PDA control. B. bassiana with Hv 0.5 % 55 mm and with Sf 0.25 %, 50 mm and in the PDA control 32.5mm (alpha = 0.05). M. robertsii induced with Sf causing 91.6 % mortality of Sf larvae and 66.6 % in PDA, at seven days (alpha = 0.05). The supplementation of the insects increased the growth of the fungi in PDA medium, this contributed to the pathogenicity of the induced strain of M. robertsii on S. frugiperda.