Title: Appraisal of Positive Pesticides Influence on Pink Bollworm Larvae, Pectinophora gossypiella (Saunders)
Abstract: Experimentsconducted to study the toxic and biological effects of three chemicalinsecticides (chlorpyrifos, Lambda-Cyhalothrin, and Methomyl), onebiochemical insecticide (spinosad), and two bio-insecticides (Bacillusthuringiensis kurstaki Bt and Nucleopolyhedrovirus, NPV) against neonatelarvae of the pink bollworm, Pectinophora gossypiella (Saund.), were carried out underlaboratory conditions. The highest effect of tested pesticides on larvalmortalities was recorded after four days of feeding these larvae on treateddiet. Spinosad was the effective toxin (LC50=1.84 ppm) to neonatelarvae followed by chlorpyrifos (LC50= 3.06 ppm), Lambda-Cyhalothrin(LC50= 5.99 ppm) then Methomyl (LC50=23.50 ppm) but B.t.(74.84×104 I.U) and NPV (83.5×109 I.U) were the lowestones. LC50 treatments of neonate larvae with all tested insecticidesproduced reduction in larval and pupal weights especially Lambda-cyhalothrintreatment, (31.9 and 24.3 %, resp.) compared with untreated insects. Thedecreasing effect of all treatments observed in fecundity and life span ofadult females which reflected in very high percentages of insect sterility withchlorpyrifos (66.7%) and Methomyl (61%) treatments. Insignificant increase oftotal protein contents and activity of Glutathione-S-transferase enzyme wasdetected in tissues of LC50 treated larvae compared with untreated larvae,but a significant (23.5%) and highly significant (56.9%) increase in enzymeactivity were resulted by Chlorpyrifos and Spinosad treatments. A very highinhibition in activity of Acetylcholinesterase enzyme of larval tissues wasrecorded with NPV (61.3%), B.t. (58.8%), Lambda-Cyhalothrin (55.6%), Spinosad(54.4%), Chlorpyrifos (48.7%), and Methomyl (37.5%)treatments than untreated ones.