Acute exposure to fipronil induces oxidative stress, apoptosis and impairs epithelial homeostasis in the midgut of the stingless bee Partamona helleri Friese (Hymenoptera: Apidae)

Partamona helleri is an important pollinator in natural and agricultural ecosystems in the neotropics. However, the foraging activity of this bee increases its risk of exposure to pesticides, which may affect both the individuals and the colony. Thus, this study aims to evaluate the side effects of LC50 of fipronil (0.28 ng a.i. mu L-1) on the mid gut morphology, antioxidant activity and some pathways of cell death, proliferation and differentiation in workers of P. helleri, after 24 h of oral exposure. Fipronil caused morphological alterations in the midgut of the bees. The activities of the detoxification enzymes superoxide dismutase, catalase and glutathione S-transferase increased after exposure, which suggests the occurrence of a detoxification mechanism. Furthermore, exposure to fipronil changed the number of positive cells for signaling-pathway proteins in the midgut of bees, which indicates the induction of cell death by the apoptotic pathway and impairment of the midgut epithelial regeneration. These results demonstrate that fipronil may negatively affect the morphology and physiology of the midgut of the stingless bee P. helleri and impose a threat to the survival of non-target organisms. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study found that exposure to fipronil caused morphological changes in the midgut of Partamona helleri workers, but also increased the activity of detoxification enzymes superoxide dismutase, catalase, and glutathione S-transferase, indicating the occurrence of a detoxification mechanism. Furthermore, exposure to fipronil altered the number of positive cells for signaling-pathway proteins in the bee midgut, suggesting induction of cell death through the apoptotic pathway and impairment of midgut epithelial regeneration.