Laboratory Toxicity Determination and Field Efficacy Validation of Three Insecticides Against Phenacoccus solenopsis from Eggplant

ZHU Yi-yong

doi:10.13651/j.cnki.fjnykj.2025.10.011

Abstract：In order to screen the effective insecticides for controlling Phenacoccus solenopsis from eggplant,the toxicity of mineral oil,thiamethoxam and lambda-cyhalothrin against its 3 rd instar nymphs and female adults of Phenacoccus solenopsis was determined by using the immersion method in the laboratory,and the field efficacy validation trials was carried out.The results of laboratory toxicity test showed that:mineral oil,thiamethoxam and lambda-cyhalothrin showed certain toxic activity against the 3 rd instar nymphs and female adults of Phenacoccus solenopsis.The toxicity of thiamethoxam was the highest,and the LC50 values of the 3 rd instar nymphs and female adults was only 8.76 mg·L-1 and 11.24 mg·L-1,respectively.Followed by lambda-cyhalothrin,with the LC50 values of 25.41 mg·L-1 and 22.70 mg·L-1,respectively.The toxicity of mineral oil was the lowest,with the LC50 values of 178.32 mg·L-1 and 198.24 mg·L-1,respectively.The results of field efficacy test showed that:at the recommended dose,the corrected control efficacy of mineral oil was the highest at 7 days after treatment,reaching 77.8%,followed by thiamethoxam(77.0%),while lambda-cyhalothrin showed relatively lower efficacy(48.2%).Both thiamethoxam and mineral oil still maintained high efficacy(>90%)14 days after treatment,whereas the efficacy of lambda-cyhalothrin declined significantly(to only 24.5%).The results showed that thiamethoxam and mineral oil were effective insecticides for controlling Phenacoccus solenopsis,while lambda-cyhalothrin showed relatively poor efficacy and short persistence period.