Effect of Insecticide Rotations on the Susceptibility of Spodoptera littoralis Larvae to Insecticides PDF

Keywords

insecticides, S. littoralis larvae, Endrin

Abstract

The susceptibility to 3 insecticides of the 4th instar S. littoralis larvae was measured topically for the 1st generation produced from samples of the 5th and 6th instar larvae collected from the field before and after spraying of each insecticide, in two successive seasons. The single application of Endrin or the successive insecticidal rotations ending with Endrin, increased the tolerance to Endrin, while there was no tolerance to either Cytrolane or Lannate. The single application of Cytrolane or the successive insecticidal rotations ending with Cytrolane, did not cause tolerance to Cytrolane or Lannate; and the same trend was obtained for the use of Lannate or the successive insecticidal rotations ending with Lannate. Meanwhile, the susceptibility of these strains of Endrin varied in the two successive cotton seasons. The susceptibility of the 4th instar S. littoralis larvae was also studied in the laboratory with the same pattern of rotations followed in the field. The data obtained showed almost the same trend of field results, after successive treatments in three successive generations. Apparently, it is advisable not to apply one insecticide (Endrin) successively within one season.