Impact of a lambda-cyhalothrin formulation residues on larval Apis mellifera: examining midgut and fat body morphological response to insecticide chronic exposure.

This article investigates the impact of chronic exposure to residual concentrations of lambda-cyhalothrin-based insecticide (λ-CBI) found in pollen grains on the midgut and fat body morphology of larval Apis mellifera (honey bee) workers. The study found that larvae exposed to λ-CBI exhibited histopathological damage in midgut cells, including autophagic vacuoles, nuclear pyknosis, apical protrusions, and altered polysaccharide and protein distribution, indicative of apoptosis and cellular stress. In the fat body, exposed larvae showed increased polysaccharide storage and reduced lipid droplet size without overt morphological damage. Despite these cellular alterations, larval development, pupation, and adult emergence were not significantly affected. The findings suggest that sublethal, field-realistic residues of λ-CBI can induce cytotoxic effects in key larval tissues potentially compromising physiological functions, underscoring the need for careful insecticide management to protect non-target pollinators.