Toxicity of Cholantraniliprole against Different Developmental Stages of the Cotton Leafworm under Laboratory Conditions

Spodoptera littoralis management has been counted on the application of the synthetic chemical pesticides, but because
of insecticides resistant problems in the cotton leafworm, the competence of these chemical have been reduced. So, new
insecticides with different action could solve this problem. In this study, the activity of a new insecticide,
chlorantraniliprole (Coragen® 20%SC), was evaluated against different stages of S. littoralis. For egg stage of S. littoralis,
two different ages, < 24 h and 24-48 h were used and dipped in serial concentrations of chlorantraniliprole. The result
presented that the young eggs were more sensitive than the old one with LC50 value of 126.6 mg/l in case in the young
eggs while it was 144.81 mg/l in the old one. In addition, the larvae of 2nd instar were exhibited a high susceptibility to
chlorantraniliprole after 96 hrs. In contrast, when pupae were dipped in chlorantraniliprole different concentrations, the
result showed no significant pupal mortality (20%) in the lower concentration (200-800 ppm), while the highest
concentration (800 mg/l) showed 43.3% mortality. The letant effect of chlorantraniliprole at LC25 (0.036 mg/l) on 2nd
instar showed that the developmental time of larval and pupal stages has been prolonged and the percentage of
hatchability was reduced as contrasted to untreated larvae. The present results propose that Coragen® could be a
potentially effective and likely to be an alternative insecticide that can be used for S. littoralis management in Egypt.