Efficacy and Residual Analysis of Three Insecticides against Spodoptera littoralis (Boisd.) on Field-grown Tomatoes

Abstract

Spodoptera littoralis (Boisd.) is among the most destructive insect pests in Egypt, the field study was conducted at El-Beheira Governorate, Egypt to evaluate the toxicity of three insecticides against 2nd and 4th larval instars of these insect and residual effect in tomato fruit into open field application. The outcomes demonstrated that spinosad, methoxyfenzide and diflubenzuron proved to be very toxic. Semi-field application showed that spinosad was the most effective with 91.38 % and 100% insect pest mortalities at initial and residual effects against second instar larvae, respectively.  The initial effect manifested higher morality (90.25%) for fourth instar larvae when treated with diflubenzuron followed by spinosad (86.50%), then methoxyfenzide (84.25%), while the residual effects of all tested insecticides were 100% mortality. The findings additionally demonstrated that the pre-harvest intervals (PHI) for diflubenzuron, spinosad, and methoxyfenzide were 3,7 and 10 days, respectively, for tomato fruits. Following this PHI, the products are considered safe for export and local consumption, as the residue level satisfies the maximum residue limit, which is the level documented by the European Union.