<i>Beauveria Bassiana</i> Triggers Soybean Systemic Resistance and Causes Sublethal Effects in <i>Spodoptera frugiperda</i>

ABSTRACT The entomopathogenic fungus Beauveria bassiana (Bals.‐Criv.) Vuill. (Hypocreales: Cordycipitaceae) can colonize plants as an endophyte and cause lethal and sublethal effects against herbivorous pests. In this study, soybean ( Glycine max [L.] Merril.) (Fabaceae) inoculated with endophytic B. bassiana was used to assess sublethal effects on Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae). The first trifoliate leaves of soybean plants were inoculated, and second‐instar S. frugiperda were placed to feed on the second trifoliate leaves. We then evaluated the herbivory and life table of S. frugiperda , as well as the expression of genes related to plant defenses at 5, 15, and 30 days after inoculation, both with and without larval infestation. Beauveria bassiana ‐inoculated plants reduced S. frugiperda leaf consumption, pupae formation, and egg laying. Female S. frugiperda that fed on inoculated plants throughout their life produced 65.4% fewer eggs than those that fed on non‐inoculated plants. The proportion of larvae that reached adulthood was significantly lower (59.9%) compared to larvae that fed on non‐inoculated plants (89.6%). The jasmonate pathway, represented by the genes MYC2 and PR3, was upregulated 15 days post‐inoculation, indicating a time‐dependent response. A synergistic response was observed for both phytohormones JA and SA at 15 days post‐inoculation, intensifying the plant resistance. The findings provide new insights into plant‐microorganism‐insect interactions and could contribute to reducing pest incidence; in the future, this method may be incorporated into integrated pest management programs.