Toxicity and cytotoxicity of the insecticide imidacloprid in the midgut of the predatory bug, Podisus nigrispinus.

Affiliation

Departamento de Biologia Geral, Universidade Federal de Viçosa, 36570-000 Viçosa, Minas Gerais, Brazil. Electronic address: [Email]

Abstract

The selectivity of insecticides on natural enemies in pest control are an important strategy for Integrated Pest Management. However, insecticides can have side effects on non-target organisms such as natural enemies. This study evaluated the histological and cytological changes mediated by the sublethal concentration of the imidacloprid insecticide on the midgut of non-target predator Podisus nigrispinus (Heteroptera: Pentatomidae), used in the biological control of pests. Imidacloprid was toxic for P. nigrispinus with LC50 = 3.75 mg L-1 and survival of 51.8%. This sublethal concentration of imidacloprid causes histological alterations in the midgut epithelium and cytotoxic features were irregular border epithelium, cytoplasmic vacuolation, and apocrine secretions in the first 6 h after exposure with the insecticide. Apoptosis in the digestive cells occurs after 12 h of exposure in the midgut. These results suggest that imidacloprid may affect the digestive physiology of P. nigrispinus and compromise the effective predation of this insect a biological control agent. The associated use of this insecticide with the predator in pest control should be carefully evaluated.

Keywords

Apoptosis,Cytotoxicity,Digestive epithelial cells,Histopathology,Imidacloprid,Non-target organism,