Effect of Abiotic Factors on the Population Dynamics of Thrips, (Thrips tabaci Lind.) on Onion Crop

The activity of thrips on onion were gradually increased from 4^th standard week of January and continued up to 18^th standard week of May, 2012 with maximum thrips population (63.30 thrips/plant) was recorded during 15^th standard week of April when the corresponding maximum, minimum temperature and relative humidity at 7 and 14 hrs during the period were 31.00, 20.50°C 92.10 and 59.40 percent. The maximum temperature showed positive influence on thrips population (r=0.926), while minimum temperature and relative humidity at 7 hrs showed significant negative effect (r=-0.658 and-0.686, respectively).