Chemical Management of Spilosoma obliqua Walker in Greengram

Greengram the most important pulse crops in India suffers a lot due to infestation of many lepidopteran caterpillars mainly at its reproductive stage. Spilosoma obliqua Walk. Arctiidae, Lepidoptera commonly called Bihar hairy caterpillar (BHC) is categorized as the most devastating.

Field efficacy of nine new generation popular insecticides were tested in coastal saline zone of West Bengal against BHC in greengram (IPM 2–3) during 2021–2022. Leaf dip bioassay study of those selected insecticides were also conducted to compute the LC₅₀ value against the field collected as well as laboratory reared F₂ generation 3^rd instar larvae of BHC.

All the test insecticides showed lethal effect towards BHC but the magnitude of protection over control was significantly higher in spinosad (70.92%) followed by flubendiamide (70.35%). Pyriproxifen+fenpropathrin (29.92%) was proved to be the least effective treatment followed by pyriproxyfen+bifenthrin (31.91%). As per LC₅₀ value (ppm) flubendiamide showed the highest toxicity against BHC in respect of laboratory reared caterpillar and field collected caterpillar (4.49 and 6.71 respectively), while pyriproxifen + fenpropathrin the lowest (624 and 637 ppm). BHC was recorded as potent defoliator which was reflected in yield, while pod damage is not so pronounced.