Sublethal effects of deltamethrin on life table parameters of the parasitoid, Lysiphlebus fabarum (Marshall) (Hym.:Aphidiidae)

Lysiphlebus fabarum (Marshall) is an important endoparasitoid of the black bean aphid, Aphis fabae Scopoli. In this study, sublethal effects of the field recommended concentration of deltamethrin (0.5 ml a.i./l) were evaluated on the parasitoid in a growth chamber at 21±1°C, 60 ± 5% RH and a 16:8 h (L: D) photoperiod. One-day-old mummies were exposed to the insecticide via dipping method. Distilled water was used in the control treatment. The demographic parameters of emerged adults from treated mummies were studied. The results showed that the field recommended concentration of deltamethrin negatively affected biological and the stable population parameters, e.g., number of eggs laid (mummified aphids), emergence rate of adults and longevity, the intrinsic rate of increase (r) and finite rate of increase (λ) and the mean generation time (T). Overall, the results of this study indicated that deltamethrin caused deleterious effects on the parasitoid and semi-field and field tests seem to be necessary.