Seasonal Incidence of Chilli Thrips, Scirtothrips dorsalis (Hood) in Relation to Weather Parameters

Abstract

Field experiment was carried out to study the seasonal incidence of chilli thrips and its relation to weather parameters during Kharif 2019 on Chilli variety SPH-4482 at JNKVV– Dryland Horticulture Research & Training Centre, Garhakota. The population of thrips, Scirtothrips dorsalis were recorded from three leaves one each from the upper, middle and lower portion on twenty selected plants during the crop growth period. The chilli thrips started to appear in the third week of August 2019 and persisted to the first week of January 2020. The average number of thrips population per three leaves per plant during the crop season ranged from 0.39 to 13.68. In month of September, there was low number of thrips population (3.02 thrips per three leaves per plant). The maximum and minimum temperatures, morning and evening relative humidity, and rainfall were 33.2 °C, 21.2 °C, 65 %, and 0 mm, respectively, during the peak of the thrips infestation. Thereafter, the thrips population gradually decreased and reached to 5.11 thrips per three leaves per plant in first week of January, 2020. The correlation between abiotic factors (minimum temperature, relative humidity and rainfall) and incidence of thrips were negative and highly significant. However, the non-significant positive correlation was observed with maximum temperature and incidence of thrips (r = 0.1368). The correlation value for maximum temperature, minimum temperature, morning relative humidity, evening relative humidity and rainfall with incidence of thrips were 0.1368, -0.8235, -0.7763, - 0.8814 and -0.5227, respectively.