Abstract
The custard apple, Annona squamosa have been reported to have toxic and biological activities against various insect pests. Twelve natural chemical compounds were identified from A. squamosa seeds extract. Acetone and methanol extracts of A. squamosa seeds were laboratory prepared to investigate their toxicity and other biological effects against Spodoptera littoralis larvae. Toxicity of acetone and methanol seed extracts of A. squamosa against 2nd and 4th instar larvae of S. littoralis were tested at different w/v concentrations using the leaf dipping bioassay technique. The results showed that, the acetone extract was more effective against the 2nd instar larvae of S. littoralis, LC50 values were 1.9, 1.7 and 1.1%, compared with the methanol extract, LC50 values were 2.8, 2.4 and 1.6% on 8, 11 and 14 exposure days, respectively. Regarding the efficiency of both A. squamosa seeds extracts against the 4th instar larvae, the acetone extract was again more toxic than the methanol one. The LC50 values of the acetone extract were 2.9, 2.1, and 0.97%, while the LC50 values of the methanol extract were 3.2, 2.1 and 1.7% on 8, 11 and 14 exposure days, respectively. In addition, the data exhibited that, the treatment of the 2nd instars larvae of S. Littoralis with acetone seed extract of A. squamosa at LC25 and LC50 prolonged the larval and pupal duration and reduced the pupal weight. Malformations of pupae and adults were recorded.