The susceptibility of onion thrips, Thrips tabaci to Heterorhabditis indicus.

The potential of the entomopathogenic nematode, Heterorhabditis indicus against Thrips tabaci was tested on foliage and in soil at three concentrations. Soil treatment was more effective than the foliar treatment. At 1.5 million nematodes/m2, nearly 70% mortality was achieved with soil application whereas a similar dose applied to the foliage gave only 55% mortality. Soil application gave better mortality of onion thrips (62 %) at 1 million/m2 compared to foliar application at 1.5 million/m2. Probably this is because the nematodes are more effective against the soil dwelling prepupae and pupae stages of the thrips. The possible explanations for the differences are discussed.