Effective biocontrol on Nezara viridula (L.) using a biopesticide produced from Beauveria bassiana

The present work aims to assess the pathogenicity of conidia produced by Beauveria bassiana on Nezara viridula (L.) through solid-state fermentation (SSF) using beer draff as a substrate. The SSF product was evaluated with the purpose of developing a microbiological product to be used in soybean fields or other legume crops. SSF was conducted at a laboratory scale using both packed-bed and tray bioreactors, and the experiments were monitored for 12 days. The maximum conidial concentration was achieved at nine days of SSF, reaching 5.18 × 10⁹ conidia g⁻¹dm. The highest enzymatic activities were observed after seven days, with approximately 4500 U g⁻¹ dry matter (dm) for protease and 500 U g⁻¹ dry matter (dm) for chitinase.

Principal component analysis (PCA) was performed to study the effect of most of the analyzed parameters on SSF. Conidial concentration, chitinase and protease activities were determined in the SSF samples.

The pathogenicity of B. bassiana was evaluated by spraying a liquid conidial formulation on N. viridula adults for a 14-day bioassay. Maximum death percentages of 67.5 % and 96.2 % were reached at 7 and 14 days, respectively. The results indicate that producing and applying biological control products derived from B. bassiana via SSF using beer draff as a substrate are a viable alternative to chemical pesticides.