Effects of acute exposure to the insecticide fipronil on the predator Podisus nigrispinus: Histopathological insight and pesticide toxicity.

Predatory bugs such as Podisus nigrispinus Dallas play an important role in biological pest control in agricultural and forestry crops. However, the use of insecticides can negatively impact this predator, reducing its population and compromising the sustainability of agroecosystems. Fipronil, a commonly used agricultural insecticide, has been shown to damage the midgut epithelial cells of the predatory bug, warranting further investigation. This study evaluated the survival, behavior, and histological changes in the midgut of P. nigrispinus following exposure to insecticide fipronil. The insecticide's toxicity was confirmed, as evidenced by its effects on behavior, histological integrity, and survival. Predator survival varied across four tested lethal concentrations (LCs), with higher LCs causing more pronounced effects. Adult P. nigrispinus showed a preference for untreated Tenebrio molitor Linnaeus pupae over those treated with the LC₅₀ and LC₉₀ concentrations of fipronil. Fipronil-induced deterrence led to reduced prey consumption, particularly of treated pupae. Histological changes in the foregut, midgut, and hindgut epithelium included vacuolization observed at 3, 6, 12, and 24 h post-exposure. These alterations may impair gut barrier function, potentially compromising the predator's overall health and effectiveness.