Impact of Abiotic Factors on Onion Thrips (Thysanoptera: Thripidae) Aerial Dispersal in an Onion Ecosystem.

Onion thrips, Thrips tabaci Lindeman, is a significant pest of onion crops worldwide, but little is known about its patterns of aerial dispersal in the context of abiotic environmental factors. Thrips tabaci adults were passively collected from the air column above onion fields in western New York using clear sticky cards over a series of sampling periods in 2012, 2013, and 2014 while on-site weather conditions were recorded. Results indicated that T. tabaci adult densities on aerial traps during daylight averaged 279 times greater per hour than densities on similar traps at night. Adult dispersal also tended to spike during presunset, indicating that thrips initiated flight diurnally and within 1 h before sunset. Densities of T. tabaci on aerial traps increased significantly as temperature increased above 17 °C and 90% of the thrips were captured between 20.8 and 27.7 °C; no thrips were captured above 30.6 °C. Densities of T. tabaci on aerial traps decreased significantly as wind speed increased, with no thrips captured at winds exceeding 3.8 m/s (13.7 kph). In 2013 and 2014, T. tabaci densities on aerial traps prior to the passage of a cold front (relatively high atmospheric pressure and temperature with low wind speed) were significantly greater than densities after passage of the front, suggesting that T. tabaci disperses on synoptic weather systems.