Abstract
Insecticidal activity of the seed extracts of custard apple, Annona squamosa L. in petroleum spirit, ethyl
acetate, acetone and methanol against Raj, CR 1, FSS II and CTC-12 strains of the red flour beetle,
Tribolium castaneum (Herbst) was studied. The seeds were dried, powdered and extracted in Soxhlet`s
apparatus in the solvents below 60°C. Extractions were applied on larvae and adult beetles in filmresidue
methods and mortality was recorded after 24 h. For larval bioassay the highest toxicity was
recorded for petroleum spirit extract (LD50= 0.03μg cm-2) in Raj strain and the lowest toxicity was for
methanol extract (LD50=15.697μg cm-2) in FSS II strain. In adults petroleum spirit extract offered highest
toxicity (LD50= 58.697μg cm-2) in CTC 12 strain and the lowest toxicity (LD50=22004.710μg cm-2) was for
acetone extract in CR 1 strain. LD50, 95% confidence limits and regression equations are presented