Comparative Assessment of Toxicity, Persistence, and Latent Bio-Effects Post Semi-Field Treatment of Some Conventional and Non-Conventional Insecticides upon the Cotton Leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae).

Abstract

: In the cotton fields, Spodoptera littoralis , a polyphagous lepidopteran insect, is known as a major pest since it destroys the entire cotton crop cycle and results in considerable economic losses. Perfect tactics for integrated pest management programs based on choosing which insecticides would be effective under the field conditions. The current study targeted to compare the initial, persistence and residual effect of non-conventional insecticides with various modes of action (Pyridalyl, Emamectin benzoate, Indoxacarb, and Triflumuron) and the conventional insecticide (Prophenofos) against the fourth instar larvae of S. littoralis field strain. Pyridalyl was the most effective with a high initial kill (93.25%) followed by Emamectin benzoate (90.31%) with longer residual effects. Pyridalyl showed the maximum persistence periods with LT 50 (5.87 days) followed by Emamectin benzoate and Profenofos, which came in the second order with 1.62 and 1.37 days, respectively. All the tested insecticides caused latent effects after treatment. Pyridalyl and Triflumuron significantly prolonged the larval duration, followed by Emamectin benzoate and Profenofos. Pyridalyl and Emamectin benzoate treatments caused significantly high percentages of malformed pupae. All the insecticides reduced the adult emergence percentages. Profenofos, Emamectin benzoate and Pyridalyl reduced the fecundity percentage. Pyridalyl and Emamectin benzoate significantly prolonged the egg incubation period. Pyridalyl, Emamectin benzoate and Profenofos reduced egg fertility. Pyridalyl is thought to be an effective insecticide in Egyptian cotton fields infested with S. littoralis larvae followed by Emamectin benzoate with great safety for mammals and beneficial arthropods as part of an integrated pest management program.