Impact of two nano-pesticide formulations in combating the two-spotted spider mite, Tetranychus urticae Koch, and their residues in cucumber fruits, Cucumis sativus L.

Nano-pesticides aim to improve the efficacy and safety of conventional pesticides, but as they are still in the early stages of development, data about their environmental fate is insufficient. Therefore, the aim of this study is to compare between the conventional and nano-formulations of chlorfenapyr (CF) and emamectin benzoate (EB), by using chitosan nanoparticles as carriers and evaluating it against the two-spotted spider mite, Tetranychus urticae Koch. The loading capacities were 52.2 and 41.7%, respectively. The nanoparticles sizes of both chlorfenapyr (CF NPs) and emamectin benzoate (EB NPs) were 99.86 and 78.82 nm, respectively. The LC s were 68.8, 10.8, 3.6 and 1.1 ppm for chlorfenapyr, emamectin benzoate, nanochlorfenapyr and nanoemamectin benzoate, respectively. Thus, the nano-formulations are 6- and 3-fold more toxic than the conventional ones. The reduction percentages of T. urticae adults reached to 98.9 and 93.8% for CF NP s and EM NP s, respectively. Dissipation kinetics have been determined and the initial deposit after one hour of application was (0.95 and 0.083) and (0.12 and 0.052) mg kg for conventional and nano-formulations, respectively. The t and PHI have been determined, t were 0.8, 0.6, 0.9, and 0.4 days while PHI values were 7, 5, 3, and 1 day for conventional and nano-formulations, respectively. In conclusion, the nano-formulations exhibit high efficacy in controlling T. urticae adults and have low residue in cucumber fruits. These results cleared that the nanoformulations reduced the concentrations, the residues and increased the efficiency.