Integrated management of diamondback moth (Plutella xylostella (L.)) using Cotesia vestalis (Haliday) and Bacillus thuringiensis Berliner

The overuse of insecticides against the diamondback moth (Plutella xylostella) has developed pesticide resistance in many field populations of this pest. In the present study, the integradted management (IM) of P. xylostella using the parasitoid Cotesia vestalis and the microbial pesticide Bacillus thuringiensis var. kurstaki, in comparison with chemical control (CC) was examined in common cabbage fields of Isfahan province (central Iran). The results indicated that percentage parasitism of the P. xylostella larvae by C. vestalis was significantly different between the two management strategies for all the release times. Such that, percentage parasitism was significantly higher in IM (59.5-71.2) compared with CC (0-11.9) section of the fields. In addition, mean damage index of P. xylostella was higher on the part under IM (3.16±0.17) compared with CC part (2.24±0.11). However, there was no significant effect of management strategies on yield; the mean weight of a marketable cabbage head was 1.63±0.08 and 1.67±0.06 under IM and CC practices, respectively. IM resulted in a greater parasitism with no yield reduction, which is indicative of success of biological control-based pest management. The present study proved that combining the native parasitoid C. vestalis and the microbial pesticide Bt may successfully check natural populations of P. xylostella in common cabbage fields of Isfahan province. These findings indicated that chemical control of P. xylostella can be replaced by integrated management, which reduce environmental risks and prevent pesticide resistance and pest resurgence.