8. Toxicity of selective insecticides against sap sucking insect pests of cotton (Gossypium hirsutum)
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Abstract
The most devastating cotton crop pests including sucking insect pests like jassid, Amrasca biguttula and aphid, Aphis gossypii. The severe attack of these sucking pests in Pakistan causes yield losses of about 28 percent to the cotton crop. Chemical control such as the use of various insecticides is mainly practiced to minimize yield losses in cotton crops. Here we evaluated the toxicity of some selective insecticides under field conditions to screen out an effective insecticide against these sucking insect pests of cotton. The insecticides tested were imidacloprid 250ml/acre, acetamiprid 150ml/acre, nitenpyram 200ml/acre, movento 250ml/acre, buprofezin 600gm/acre and chlorfenapyr 225ml/acre. The results of this study revealed that all the insecticides tested were effective against A. gossypii, after 96 hours of spray, except buprofezin and movento, the other insecticides caused immature and adult mortality. Nitenpyram and buprofezin exhibited the highest mortality rate of adult aphids after 24 h of spray. When spraying nitenpyram@200ml/acre, acetamiprid@ 150ml/acre, and imidacloprid@250ml/acre, the highest mortality of A. biguttula adults was recorded after 96 hours of spray. Imidacloprid, acetamiprid, nitenpyram, and buprofezin were statistically equally effective at the immature stage with mortality of A. biguttula after 96 hours of spraying. In addition, acetamiprid and nitenpyram were more effective after 24 hours of spray, but imidacloprid, chlorfenapyr, movento, and buprofezin were less effective and showed low mortality at immature A. biguttula stage.
Keywords: Aphis gossypii; Amrasca biguttula; Insecticides; mortality; neonicotinoids; toxicity