Formulation of abiotic triggers for prediction of thrips and whitefly pest in Bt cotton under rainfed condition of Maharashtra

Thrips and whitefly is the destructive insect of Bt. cotton worldwide. We analysed infestation dynamics of these pests in Bt. cotton during crop growing season of 2002–2018 (17 years), and predicted the factors influencing its abundance. Rainfall, maximum-minimum temperature, maximum-minimum relative humidity, bright sunshine hours and wind influencing the thrips and whitefly population build-up were predicted using MRM technique with reasonable accuracy (R square= 0.83 to 98). The results also showed that light rainfall (<13 mm/h) and medium rainy days (2–3 rainy days/week) combined with light air (WV<4–6 km/hr) and moderate to partially cloudy condition (BSS of 5–8 hrs./day) prevailing coupled with T_max (30.0–33.0 ⁰C) for both pest, and T_mln (21.0–22.0 ^oC), RH-I >80% and RH-II >50% for thrips and T_mln (15.022.0 ^oC), RH-I >75% and RH-II >40% for whitefly are favourable to build up optimal population (or above ETL) during the period 34–39 SMW and 38–44 SMW respectively, in which time required management to control both pest.