Seasonal Abundance of Thrips, Thrips tabaci on Garlic and Its Correlation with Weather Parameters and Their Predators

Abstract

A field study was conducted during Rabi, November to April, 2024–25 at the College Farm, N. M. College of Agriculture, Navsari Agricultural University, Gujarat, to examine the seasonal abundance of thrips, Thrips tabaci Lindeman, on garlic variety (Gujarat Garlic-7) and its association with weather parameters and predators as thrips are major attacking pest of garlic that causes significant damage by sucking sap and transmitting viral diseases. The initial infestation was recorded during the 50th Standard Meteorological Week (SMW) with 2.32 thrips per plant. The population gradually increased, reaching a peak of 41.30 thrips per plant in the 10th SMW (1st week of March) and declined thereafter toward crop maturity. Correlation analysis (OPSTAT analysis tool) revealed a significant positive relationship between thrips population and bright sunshine hours (r=0.462*), while evening relative humidity showed a highly significant negative correlation (r=−0.694**). Other weather parameters like maximum and minimum temperatures, morning humidity and wind speed showed non-significant effects. Natural enemies appeared from the 50th SMW. The ladybird beetle population peaked at 2.29 per plant in the 9th SMW and spiders at 2.61 per plant in the 8th SMW. Their populations showed a highly significant positive correlation with thrips population (r=0.921** for beetles and r=0.889** for spiders), suggesting a strong predator-prey relationship. Overall, the findings indicates that the seasonal abundance of thrips and their predators are strongly influenced by prevailing weather parameters, suggesting a well-defined ecological balance between pest and predator.