Histopathological effects of plant extracts on Anopheles gambiae: acute and chronic toxicity assessment

The increasing use of plant-derived insecticides for malaria vector control necessitates comprehensive evaluation of their histopathological effects on target organisms. This study investigated acute (24-hour) and chronic (72-hour) tissue damage in Anopheles gambiae exposed to methanol, ethanol, and ethyl acetate extracts of Eucalyptus citriodora, Azadirachta indica and Albizia lebbeck. Using standardized hematoxylin and eosin staining protocols, we observed severe midgut epithelial vacuolization (mean severity score 4.4±0.5) following acute exposure to methanol extracts, progressing to complete tissue necrosis during chronic exposure. Ethyl acetate extracts demonstrated significantly milder effects (p<0.001), suggesting solvent-dependent toxicity patterns. These findings provide crucial insights into the mechanisms of action of botanical insecticides while highlighting the need for careful consideration of solvent selection in formulation development. The study contributes to the growing body of evidence supporting plant-based alternatives for vector control, particularly in resistance management strategies.