Efficacy of the traditional and nano-forms of thiocyclam and chlorantraniliprole against Spodoptera littoralis and Agrotis ipsilon and analysis of their residues in tomato fruits

Abstract

For effective pest control, nano-insecticides have recently been proposed as a promising alternative to traditional ones. Thus, this study aimed to compare the efficacy of the traditional and nano-forms of thiocyclam (a natural toxin-based insecticide) and chlorantraniliprole (a diamide insecticide) against two major insect pests, the cotton leafworm, Spodoptera littoralis (Boisd.), and the black cutworm, Agrotis ipsilon (Hufnagel). The residue levels of the two insecticides in tomato fruits were also assessed. The results showed that chlorantraniliprole was more effective against both insects than thiocyclam, and the nano-forms were more effective than the traditional ones. This higher insecticidal activity of chlorantraniliprole could be attributed to its novel action by binding tightly to ryanodine receptors in insects. The study also optimized and validated an analytical method for residue determination of thiocyclam and chlorantraniliprole in tomato fruits using QuEChERS method and LC-MS/MS. Percentage recovery ranged from 70 to 104%, with good precision and expanded uncertainty of up to ± 23%. The half-life times of thiocyclam and its nano-form in tomatoes were 0.38 and 0.57 days, respectively, compared to 0.7 and 0.38 days for chlorantraniliprole and its nano-form. On the other hand, the calculated pre-harvest intervals for thiocyclam and its nano-form, using the EU maximum residue limit, were 7 and 3 days, respectively, compared to 1 day for both forms of chlorantraniliprole.