Preparation cypermethrin microemulsion formulation and evaluation its insecticidal activity on Aphis gossypii(Hemiptera: Aphididae) in green space of Ahvaz

A microemulsion is a stable, homogeneous pesticide formulation, based on an aqueous solvent, which is considered a suitable alternative to emulsion formulations. In this study, microemulsion formulations of cypermethrin insecticide were designed to control Aphis gossypii Glover (Hemiptera: Aphididae), one of the important pests of many crops and ornamental plants.  Xylene was selected as a suitable solvent based on the higher solubility of cypermethrin. Pseudo-ternary phase diagrams were constructed by the water titration method. The microemulsion system using mixtures composed of cypermethrin, Kenon 10+SDS surfactants, and 1-butanol cosurfactant had the highest microemulsion surface, and the ratio of 50:30:20 was chosen for further experiments. The physical and chemical properties of the obtained microemulsions were also evaluated. Microemulsion formulations were synthesized with 150 and 250 g/L a.i. (active ingredient) of the cypermethrin. The appearance of the microemulsion compounds was transparent and the droplet size of all samples was less than 35 nm. Foliar spraying of compounds including cypermethrin technical material (150 g a.i./L), cypermethrin technical material (250 g a.i./L), cypermethrin microemulsion (150 g a.i./L), and cypermethrin microemulsion (250 g/L a.i.), under greenspace conditions on Hibiscus rosa-sinensis L. (Malvaceae) caused 25.05, 37.54, 60.74, and 83.94% mortality on third instar nymphs 48 hours after treatment, respectively. Therefore, microemulsion formulations had significantly more insecticidal activity against A. gossypii compared to the technical material. In this study, an environment-friendly microemulsion system was designed to improve the efficacy of cypermethrin for controlling populations of A. gossypii. However, further research could be performed to assess the behavior and ultimate fate in the environment prior to commercialization.