Monitoring Aphis gossypii Glover Resistance to Certain Insecticides in Cotton Fields and Activity of Some Detoxification Enzymes

Aphids resistance to insecticides is an increasing problem because insecticides are an integrated part of high–yielding  productive of cotton.  Therefore, aphid population, Aphis gossypii Glover collected from cotton fields at the Sakha Agric. Res. Station Farm, Kafr El-Sheikh, Egypt, in 2014 and 2015 seasons, was screened for resistance to five insecticides belonged to different groups in addition to activity of some detoxification enzymes. Generally, aphid population was less susceptible to all the tested insecticides in season of 2015 than 2014. Results of LC₅₀ s indicated that carbosufan was the most toxic insecticide against laboratory strain of A. gossypii. Malathion in season of 2014 and carbosulfan, imidacloprid and chlorpyrifos in season of 2015 gave the highest toxic effect against the field population, while lambda-cyhalothrin exhibited the least toxic effect against both laboratory strain and the field population. Field population showed high resistance to carbosulfan in the two seasons, while resistance to malathion was moderate in the second season only. The resistance to lambda-cyhalothrin, chlorpyrifos and imidacloprid was low in the two study seasons. Based on the susceptibility factor, chlorpyrifos only could be effective against aphids at recommended field rate in the two study seasons, while malathion was effective in season of 2014 only. Activity of AChE and α-esterase was higher in the field population than the laboratory strain in the two seasons. The field aphids exhibited high concentration of total protein compared to the laboratory strain, while the reverse was found in case of lipids.
However, the obtained results could be useful in developing an integrated insect management programs in cotton fields.