Preparation of alphacypermethrin and fipronil emulsifiable concentrates using different concentrations of the modified polytrisiloxane (QS-۳۰۲)

The present research aimed to enhance the efficacy of alphacypermethrin and fipronil insecticides formulated as an emulsifiable concentrate (EC) by adding varying concentrations of the modified polytrisiloxane (QS-۳۰۲) as an adjuvant alongside the emulsifier blend. The formulations were subjected to emulsion and thermal stability tests according to the methods used by both the FAO and WHO to determine qualified pesticides. Using the residual thin film technique, the acute toxicity of prepared formulations was also assessed against adult rice weevil Sitophilus oryzae (L.). Generally, alphacypermethrin demonstrated greater effectiveness than fipronil, with LC۵۰ values of ۱.۵۴۵ ppm for alphacypermethrin compared to ۸.۶۰ ppm for fipronil. When the QS ۳۰۲ adjuvant was incorporated at a concentration of ۷% into the EC formulations, the LC۵۰ for fipronil decreased from ۸.۶۰ ppm to ۵.۹۸ ppm. Also, at a ۱۴% addition of QS ۳۰۲, the LC۵۰ value dropped to ۲.۹۲ ppm. In contrast, the efficacy of alphacypermethrin against rice weevils diminished when QS ۳۰۲ was mixed with the other components at the same concentration. This may be attributed to the enhanced pesticide penetration and distribution of fipronil, which was improved more than that of alphacypermethrin due to alterations in the hydrophobic-hydrophilic balance (HLB), ultimately affecting the solubilization and penetration of the insecticide through the rice weevil cuticle.

کلیدواژه ها:

emulsifiable concentrate ، formulation ، insects ، polytrisiloxane