Comparison of absolute estimates of Thrips tabaci (Thysanoptera : Thripidae) with field visual counting and sticky traps in onion field in south Texas

摘要

Absolute estimates of onion thrips, Thrips tabaci Lindeman, on onions were used to determine the reliability of field visual counting, and blue and white plastic cup traps and CC traps for monitoring thrips in onion fields. It took >140 min to sample one plant for the absolute estimates of thrips, which was approximate to15-fold longer than needed to sample one plant by field visual counting, and 3.8- and 4.3-fold longer than processing a sample using a plastic cup trap or a CC trap sample, respectively. Results indicated that adult thrips comprised approximate to16.4 and 15.8% of total thrips in the absolute estimates and field visual counting, respectively, and were well correlated with total thrips in each sampling method (r = 0.81 and 0.73, respectively). Total thrips and adults by field visual counting estimated approximate to75% of total thrips and approximate to78% of adults of the absolute estimates, and were highly correlated with the absolute estimates (r = 0.98 and 0.95, respectively). Blue plastic cup traps caught the most thrips (19-23 thrips/trap/day), followed by white plastic cup traps (10-12 thrips/trap/day), compared with <1 adult thrips/trap/day on CC traps. Adults caught on the sticky traps were not well correlated with numbers of thrips on onion plants in the field (r = 0.07-0.61). Field visual counting of either all thrips or only adults on onion plants was quick and provided >95% precision.