Biology and Control of the Onion Thrips in India

The life cycle of onion thrips, Thrips tabaci Lindeman, in the laboratory required 21 days during December and January and 14 days in. April. Females laid an average of 15.6 eggs in clusters inside the epidermal layer of the leaves. Adult females lived an average of 19.67 days. Both adults and larvae usually fed on plant sap. Feeding usually caused yellowing and dropping of leaves. High infestations resulted in stunted growth, white leaf blotches, and low yields. Thrips were active on various host plants throughout the year, and were most active on onion from October to May. White Spanish onions were most resistant to damage; Poona red was highly susceptible. Highest infestations (31.5 per plant) occurred in fields of sandy loam soil with high levels (0.095%) of nitrogen and low levels of phosphorus (0.01%) and potash (0.006%). Low infestations occurred in fields of clay soil with low levels of nitrogen (0.065%) and higher levels of phosphorus (0.013%) and potash (0.007%). Of 8 materials tested, parathion spray (0.02%) provided the best control.