Recently, a plant protection strategy has been recommended, minimizing the use of chemical pesticides. Therefore, the study was conducted to determine the efficacy of commonly used insecticide chemicals in cotton mealybug, Phenacoccus solenopsis Tinsley, and their toxicity against natural enemies of mealybug on Deltapine-90 cotton variety at Werer Agricultural Research Center during the 2016 cropping season. The treatment included six insecticides (Sulfoxaflor, Dimethoate, Profenofos, Alphacypermethrin, Chlorantraniliprole, Carbosulfan compared with Control/Water). The experiment was three times replicated randomly. Mealybugs and their natural enemies' pretreatment and post-treatment data counts were recorded and compared statistically. Treatments were applied when the economic threshold level of the cotton mealybug reached 110 per plant. The post-treatment counts on the mealybugs and natural enemies were recorded on 3rd, 5th, 7th, 10th, and 15th days after treatment application. The field was sprayed two times with attaining an economic threshold level in a 21days interval to test efficacy to mealybugs. Pesticides toxicity effects assessed on the natural enemies. The laboratory evaluation was carried out to confirm the toxicity of each insecticide product to existing parasitoids and predators. The results showed that all the tested insecticides were effective for up to three days in reducing cotton mealybug. However, Profenofos showed 68.8% efficacy for up to 10 days followed by Dimethoate 49%. The activity of natural enemy both predators and parasitoids were impaired by the application of insecticides. The maximum number of predators and parasitoids were in the control plots, followed by insecticide-treated plots, with Chlorantraniliprole, Alphacypermethrin, and Sulfoxaflor. The results from field sprays and laboratory dip bioassay experiments revealed that Profenofos, Dimethoate, and Carbosulfan were the most toxic insecticide chemicals. The yield and quality of cotton fiber were lower in control plots, followed by Chlorantraniliprole. The yields and quality of cotton fiber were good for insecticide-treated plots with profenofos. From these premises, signify concluded that the effect of commonly used insecticide chemicals in the cotton plant was more acute for cotton mealybug natural enemies than cotton mealybug.

Keywords: Cotton, Quality, Insecticide, Predators, Parasitoids, and Toxicity