Spatio-temporal patterns of black thrips, Thrips parvispinus (Karny) in chilli cultivation: linking climatic variability to pest outbreaks

AbstractPresent study was conducted during rabi 2023-24 and summer 2024, aimed to elucidate the seasonal population dynamics of T. parvispinus on chilli twigs and their relationship with key weather parameters. During rabi, infestation commenced in November (44th standard meteorological week [SMW]) at 0.45 thrips per twig and peaked in the 6th and 7th SMWs with 9.32 and 9.58 thrips per twig, respectively, before declining by the 8th SMW. Thrips density exhibited significant positive correlations with maximum temperature (r = 0.61**), afternoon relative humidity (r = 0.09**), and sunshine hours (r = 0.20), but was negatively correlated with minimum temperature (r = -0.68). Floral thrips density similarly showed a positive correlation with maximum temperature (r = 0.62*), indicating that elevated daytime temperatures promote thrips activity during rabi. In summer, infestation began at 7 days after transplanting (10th SMW) with 1.50 thrips per twig, reaching a peak of 12.15 thrips per twig at 77 days after transplanting (20th SMW), followed by a gradual decline. Contrary to rabi, summer thrips density negatively correlated with maximum temperature (r = -0.30), afternoon relative humidity (r = -0.24**), and sunshine hours (r = -0.50), but positively correlated with minimum temperature (r = 0.72). Floral thrips density also negatively correlated with maximum temperature (r = -0.26). These contrasting seasonal patterns underscore the complex influence of climatic variables on T. parvispinus population dynamics, reflecting the pest’s adaptation to varying environmental conditions.