Evaluation of Grower-Oriented Sampling Techniques and Proposal of a Management Program for Potato Leafhopper (Homoptera: Cicadellidae) in Alfalfa

Abstract

A sampling study was conducted from 1994 to 1996 comparing 4 grower-oriented sampling techniques (sticky trap, suction, sweep, and water pan) with an absolute (drop trap) technique for estimating density of potato leafhopper, Empoasca fabae (Harris), in alfalfa. For each relative sampling technique, the number of adults or adults and nymphs combined (total) were regressed on the number of adults or adults nymphs combined from the absolute technique. The relative variation and relative net precision of each sampling technique also were calculated as well as the optimum number of sampling units required for each technique for a desired precision. Based on the regression analysis and comparison of relative variation and relative net precision, suction (adult), sweep (adult), and sticky trap (48 hr) are all adequate sampling techniques for estimating adult potato leafhopper population levels. Economic thresholds were calculated from economic injury levels for each of these techniques by using different alfalfa prices and management costs. Because of the low relative variation and high relative net precision, the sticky trap sampling technique seems the most promising technique as an alternative to a sweep sampling technique for use in a management program in alfalfa. A program using sticky traps for estimating potato leafhopper density is proposed.