Deltamethrin as a potential ovicidal pyrethroid against Plutella xylostella L.

The effect of deltamethrin on the hatching of eggs of two strains, susceptible (S) and resistant (R), of Plutella xylostella was investigated. Daily observations were made on the development of the embryos, hatching and larval mortality after treatment with different dosages of deltamethrin. This compound exhibited a dosage-mortality response against the S-strain eggs. The hatching of the R-strain eggs was also affected by deltamethrin but to a lesser extent. At least 50% of the S-strain larvae that hatched from the treated eggs died within a few hours, but the larvae of the R strain were more resistant. Seedlings treated with different dosages also showed a drop in egg hatching and less damage on the leaves. Deltamethrin had no effect on embryonic development.