Relative Toxicity and Residual Activity of Nanocapsules and Commercial Formulations of Pirimicarb and Pymetrozine Against Myzus persicae (Hemiptera: Aphididae).

The green peach aphid, Myzus persicae (Sulzer), is one of the most common pest species that has the potential to transmit more than 100 plant viruses. Controlling this pest is difficult because it has become resistant to a wide range of insecticides. Nanoformulation has the capacity to reduce the pesticide load in agriculture and thus reduce the risks on human health and the environment. In this study, nanocapsules of pirimicarb and pymetrozine were prepared using nanostructured lipid carriers. The size, morphology, and encapsulation efficiency of nanocapsules were investigated using dynamic light scattering, scanning electron microscopy, and UV-VIS spectrophotometer. Zeta potential studies revealed stability of the nanocapsules of both insecticides. The encapsulation efficiencies were 85 and 81% for pirimicarb and pymetrozine, respectively. The nanocapsules were spherical with sizes of 35.38 and 35.12 nm for pirimicarb and pymetrozine, respectively. The LC50 values for the wettable powder (WP) and nanocapsule of pirimicarb after 48 h were 216.2 and 73.2 mg ai/l; for pymetrozine after 96 h, the values were 40.6 and 14.8 mg ai/l, respectively. Durations of residual activity for WP and nanocapsule formulations of pirimicarb were 7 and 15 d, respectively. The residual activity periods for WP and nanocapsule formulations of pymetrozine were 9 and 17 d, respectively. The results revealed that nanoencapsulation can improve performance allowing for reduced doses and increased duration of insecticidal activity for both of the insecticides tested.