Entomopathogenic fungi disrupt the feeding behavior of Euschistus heros in soybean

This study evaluated the effects of the entomopathogenic fungi on the feeding behavior of the Neotropical brown stink bug, Euschistus heros, using electropenetrography (AC-DC) technology. Twenty females per treatment were reared under controlled conditions and exposed to soybean pods treated with fungal suspensions (2 µL on the pronotum with 5 × 10⁶ and 6.15 × 10⁸ conidia mL^{- 1} for Cordyceps javanica and Metarhizium anisopliae, respectively), chemical insecticide (Thiamethoxam + Lambda-cyhalothrin, 0.025/100 mL), and aqueous solution of Polysorbate 80 (0.01% v/v) (control). Response variables associated with count and duration of feeding behavior over 72 h of recording were modelled using GAMLSS (generalized additive models for location, scale, and shape) to assess the statistical significance of treatments and for pairwise comparisons of means (p < 0.05). The fungal treatments and chemical insecticide significantly reduced the frequency and duration of feeding events, especially stylet penetration and seed ingestion, compared to untreated controls. Additionally, insects treated with fungi spent more time in non-feeding behavior, indicating disrupted feeding behavior. Both fungi also shortened the duration of the final feeding probe by about 13 h. Furthermore, electropenetrography enables assessment of pest-plant interactions and biocontrol efficacy beyond mortality.