The integrated effect of the nematode-bacteria complex and neem plant extracts against Plutella xylostella (L.) larvae (Lepidoptera: Yponomeutidae) on Chinese cabbage

摘要

The compatibility of the nematode-bacteria complex of Steinernema carpocapsae, S. abbasi, and Heterorhabditis bacteriophora with neem plant extracts (seeds and leaves) to control diamondback moth, P. xylostella on Chinese cabbage plants was investigated under laboratory conditions. The initial treatment of Chinese plant leaves with neem plant extracts resulted in more susceptibility of P. xylostella to neem seed extract than neem leaf extract. The combination studies resulted in a higher synergistic effect of nematode-bacteria complex of H. bacteriophora, S. abbasi and S. carpocapsae with neem seed extract compared with that of S. abbasi with neem leaf extract. In contrast, the combination of nematode-bacteria complex of S. carpocapsae and H. bacteriophora with neem leaf extract recorded an antagonistic effect. On the other hand, the time-mortality response was more reduced with neem seed extract than with neem leaf extract, besides it was a concentration-dependent factor. We conclude from theseinvestigations that the combination of entomopathogenic nematodes with neem plant extracts could be successful in controlling P. xylostella on Chinese cabbage plants in the field.