Toxic and Biochemical Effects of Some Bioinsecticides and Igrs on American Bollworm, Helicoverpa armigera (h u b.) (noctuidae: lepidoptera) in Cotton Fields

摘要

Field experiments were carried out to evaluate efficiency of three bioinsecticides (Dipel DF, Protecto and Bioranza) and two insect growth regulators (IGRs) (chlorfluazuron and pyriproxyfen) against larvae of American bollworm, Helicoverpa armigera (ABW) and their side effects on some common predators in Egyptian cotton fields during 2009 and 2010 at Aga region, Dakahlia Governorate, Egypt. Results indicated that chlorfluazuron showed the highest initial reduction (75.00 and 80.6%); residual mean (83.75 and 79.45%) and annual mean (80.83 and 79.83%) on H. armigera during the two successive seasons, respectively. Moreover, chlorfluazuron was the most toxic and gave the highest reduction in predator numbers recorded (20.70, 23.20 and 22.37%) in the 2009 season and (23.30, 20.90 and 21.70%) in the 2010 season at the initial, residual and annual means, respectively. Chlorfluazuron, pyriproxyfen and Dipel DF gave the lowest significant decrease in the activity of amylase enzyme (61.86 and 59.86% relative to control), invertase enzyme (75.28 and 80.13%) and trehalase enzyme (73.64 and 83.74%), respectively after 3 and 7 days post treatment. Insect growth regulators (chlorfluazuron and pyriproxyfen) caused highly significant increases in the activity of chitinase enzyme (130 and 122.6% 141.89 and 131.64%, respectively) at both interval times, respectively.