The Integrated Effect of the Nematode-Bacteria Complex and Neem Plant Extracts Against Plutella Xylostella (L.) Larvae (Lepidoptera: Yponomeutidae) on Chinese Cabbage

The compatibility of the nematode-bacteria complex of Steinernema carpocapsae, Steinernema abbasi, and Heterorhabditis bacteriophora with neem plant extracts (seeds and leaves) to control diamondback moth, Plutella xylostella (L.) 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 seeds extract than neem leaves extract. The combination studies resulted in a higher synergistic effect of nematode-bacteria complex of H. bacteriophora, S. abbasi and S. carpocapsae with neem seeds extract compared with that of S. abbasi with neem leaves extract. In contrast, the combination of nematode-bacteria complex of S. carpocapsae and H. bacteriophora with neem leaves extract gave an antagonistic effect. On the other hand, the time-mortality response was more reduced with neem seeds extract than with neem leaves extract, besides it was a concentration dependant factor. We conclude from these investigations that the combination of entomopathogenic nematodes with neem plant extracts could be of success in controlling P. xylostella on Chinese cabbage plants in the field.