The Efficacy of Spinosad on Different Strains of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae)

The cotton leafworm, Spodoptera littoralis (Boisduval), was collected from commercial cotton production fields in Adana,Turkey, and tested for susceptibility to the insecticide spinosad. The susceptibility of the field strain was also compared to the susceptible strain (S) of S. littoralis. Lethal dose bioassays were performed with third instar larvae using the leaf dip method. TheLC50 values for field and susceptible strains were 43.691 and 10.037 ppm, respectively. When LC50 values and 95% confidence intervals were compared with a susceptible laboratory reference strain, the field strain was approximately 4.4-fold less sensitive than the susceptible strain. The present study suggests that spinosad is potentially important in the control of S. littoralis.