Toxicity and Residual Effect of Annona squamosa L. and Piper nigrum L. Seeds Extracts against Tribolium castaneum and Sitophilus oryzae

Giving the importance of maintaining the inventory materials of the loss as a result of insect infestation, this research aims to evaluate the activity of Piper nigrum L. and Annona squamosa L. seeds extracts against Tribolium castaneum and Sitophilus oryzae. Bioassay tests were conducted by using the waved filter paper in plastic Petri dishes 9cm and residual film in glass Petri dishes 5 cm with four concentrations, 0.25, 0.5, 0.75 and 1% of P. nigrum petroleum ether extract and A. squamosa ethanol extract. LC50 values were 0.23 and 0.31% after 24 h of exposure of P. nigrum and A. squamosa, respectively against S. oryzae, and they were 0.16 and 0.35 % after 24 h, against T. castaneum. Moreover, P. nigrum was more repellency than A. squamosa against the both insects. Noticeably, the repellency effect increased with increasing the time of exposure of P. nigrum and A. squamosa against T. castaneum. While, it decreased after 10 h against S. oryzae. The A. squamosa extracts was more toxicity and persistence than P. nigrum extract with the prolongation of time to 30 days. Whereas, the mean mortality percentages were 80 and 51.67%, respectively. We can conclude that, Annona squamosa and Piper nigrum extracts will be used to control stored product insects.