Potency of different insecticides against the cotton bollworms in relation to pesticide residues in bolls
2011
Mahmoud, N.N.H.
The life table, efficacy of certain insecticide agaist P .gossypiella ' and their effect on the larval populatIon and InfestatIon wIth both pInk (p. gossypiella) and spiny (E. insulana) bollworms were studied during two , successive cotton growing season. The persistence of lambda cyhalothrin and chlorpyrifos in and on cotton bolls was also investigated. Esfenvalerate gave the highest effect on I, 2... and 3 days old eggs whereas profenfos and chlorpyrifos gave the highest ,effect on 4 days old eggs.Es fenvalerate was the most potent compound against larvae and moths while hexaflumuron was the least potent compound.Esfenvalerate highly decreased Mx, Lx, Ro, rm, em values and increased T and DT values compared to other compounds. Esfenvalerate gave the highest reduction (76% and 78.7%) in larval population and infestation, respectively, in 2006 cotton season and the highest reduction (65.3% and 54.7%) in larval population and infestation respectively, in 2007 cotton season. Hexaflumuron gave the least reduction (43.3% and 58'.8%) in larval population and infestation, respectively, in 2006 cotton season and the least reduction (13.3% and 11.8%) in larval population and infestation, respectively, in 2007 cotton season. The residues of lambda cyhalothrin and chlorpyrifos in cotton bolls were determined externaly and internaly. The total recovered amounts of choroyrifos was 199.4,81.5,30.3,7.63,3.1,1.5,0.83 and N.D .while the corresponding values for lambada cyhalothrrin were 18.75,14.05,10.08, 8.03,4.43,4.08, 1.84 and N.D. for initial deposit 1,3, 5, 7, 10, 14 and 21 day, respectively.
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