Abstract

Among these inputs, the entomopathogenic fungus Metarhizium anisopliae stands out in biological pest control, but its effects on native bees remain poorly investigated. This study evaluated the ecotoxicity of a M. anisopliae-based bioinsecticide on the stingless bee Tetragonisca angustula, a species native to Brazil with recognized ecological and agricultural importance. Laboratory assays were conducted to determine lethal concentrations for 10% (LC₁₀) and 50% (LC₅₀) of bees, as well as the no-observed-effect concentration (NOEC) and lowest-observed-effect concentration (LOEC), considering two exposure routes: topical and oral (residual). Results showed that topical exposure was more toxic (LC₅₀ = 1542.57 mg/L) compared to oral exposure (LC₅₀ = 5984.47 mg/L), confirming higher risk through direct contact with the bioinsecticide. Behavioral assays indicated significant sublethal effects on feeding preference from 10 mg/L (LOEC), while 5 mg/L was established as the NOEC. These findings demonstrate that even at low concentrations, M. anisopliae can alter the feeding behavior of T. angustula, compromising its pollination efficiency. Although laboratory conditions represent high-exposure scenarios, the data reinforce the need for ecotoxicological assessments specifically targeting native bees. The results generated may support regulatory agencies, inform public policies, and guide the safe use of bioinputs, helping to reconcile agricultural productivity with biodiversity conservation.