Various ways of measuring thrips populations have been evaluated experimentally at the Yuma Ag Center. For example one method involves washing plants and collecting the total number of insects, and then comparing them to direct counts from plants in the field. Although the plant wash procedure is very accurate it is expensive and time consuming. However, the procedure that is currently used by entomology technicians at the UA is the beat pan method. This relative sampling procedure consists of beating lettuce plants in a square pan covered with wire mesh where a 6x6" yellow sticky trap is placed in the bottom of the pan to collect the dislodged thrips. For optimal thrips collection, sampling is done by beating the outside foliage of the plant against the screen, and then hitting the centers and bottom of the plants against the pan. The project manager determines the number of plants to be sampled per experimental plot which is normally replicated 4 times and randomized throughout the field. After collecting the beat pan sample, the sticky traps are covered with clear wrapping paper then taken to the laboratory where thrips larvae and adults of the different species are identified and counted under a stereomicroscope. The results of this sampling technique are fairly precise compared to whole plant washes. For experimental purposes, thrips numbers collected from the beat pan method provide statistically similar treatment differences compared with the plant wash method, even when only a percentage of the insects are collected. This sampling method is also a lot less time consuming. For more information on this sampling technique visit: http://cals.arizona.edu/pubs/crops/az1323/az1323_1b.pdf and watch the video demonstration of this technique below:

Western Flower Thrips adult on sticky trap

To contact Marco Peña go to: marcop@ag.arizona.edu

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.