Abundance of major sucking insect pests on chilli in relation to weather factor and their management with newer insecticide molecules during rabi season under red and lateritic zone of West Bengal

Abstract

Seasonal abundance of chilli aphids initiated on or before 3rd week of January and chilli thrips initiated on or before 4th week of January at early stages of the crop. Aphid population build up gradually increased and attained at peak on 4th week of February and remained high till 3rd week of March. Thrips population was high in the field in 9 to 11 Meteorological Standard Weeks (MSW). In the present investigation, population fluctuations of chilli aphid affected mainly by three weather parameters as this was evident from the negative correlation with minimum temperature (r=-0.141), rainfall (r=-0.474) and relative humidity (r=-0.454). However, relative humidity (r=-0.616*) showed significant negative correlation in the population fluctuation of chilli thrips. Results on multiple regression analysis revealed that 31.3% (R2= 0.312) variation in aphid population was happened due to the abiotic factors while it was 45.4% (R2= 0.0.454) for thrips population. Results on efficacy of the seven insecticides revealed that both aphid and thrips population was significantly lower in Imidaclorprid (T4) and Thiamethoxam (T2) at different days after both spraying as compared to control. The highest yield (88.71 q/ha) was obtained in T4 (Imidaclorprid) which was statistically significant to T8 (Control). As far as the incremental cost benefit ratio (IBCR) is concerned, an outstanding outcome has been observed on performance of the treatments. The IBCR for Imidaclorprid (4.17) recorded maximum followed by Thiamethoxam (4.02) and Fipronil (3.93).