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United States Department of Agriculture

Agricultural Research Service

Title: Evaluation of Sampling Methods and Development of Sample Plans for Estimating Predator Densities in Cotton

Authors
item Knutson, A - TEXAS A&M EXT DALLAS
item Muegge, M - TEXAS A&M EXT FT STOCKTON
item Wilson, L - TEXAS A&M EXT BEAUMONT
item Naranjo, Steven

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 3, 2008
Publication Date: September 9, 2008
Citation: Knutson, A.E., Muegge, M.A., Wilson, L.T., Naranjo, S.E. 2008. Evaluation of Sampling Methods and Development of Sample Plans for Estimating Predator Densities in Cotton. Journal of Economic Entomology 101(4): 1501-1509.

Interpretive Summary: Predatory arthropods are ubiquitous in cotton fields in the southwest and western USA and contribute significantly to biological control of many cotton pests. Various methods have been developed and used to sample predatory arthropods but no standard methods exist for sampling these organisms for integrated pest management purposes. A three year, two state study was conducted to compare visual, sweep net, beat cloth, shake bucket and beat bucket sampling methods and to develop sampling plans for using the most cost-efficient device. The beat bucket sample method was the most cost-reliable while the visual sample method was the least cost-reliable. Four sample unit sizes for beat bucket sampling were evaluated. The cost-reliability of 1-, 3-, 5- and 10-plants per beat bucket sample varied with predator group, but multiple plant sample units were more cost-reliable than the one plant sample unit. Sample plans for the beat bucket method were developed for Orius, spiders, and Coccinellidae and the sum of these groups. A sample plan for estimating 0.75 predators per cotton plant required 24, 22 and 12 beat bucket samples and a sampling cost of 28, 39 and 27 minutes for the 3-, 5- and 10- plant sample unit sizes, respectively. The greater cost-reliability of the beat bucket sampling method and its ease of use is of particular advantage in assessing predator densities in commercial cotton field monitoring programs.

Technical Abstract: The cost-reliability of five sampling methods (visual search, drop cloth, beat bucket, shake bucket and sweep net) was determined for predatory arthropods on cotton plants. The beat bucket sample method was the most cost-reliable while the visual sample method was the least cost-reliable. The beat bucket sample method required a significantly shorter sample time relative to all other sample methods except the shake bucket method, and captured a significantly greater proportion of four predator groups relative to all other sample methods. These characteristics contributed to the cost-reliability advantage of the beat bucket sample method. Four sample unit sizes for beat bucket sampling were evaluated in Texas and Arizona field studies. The cost-reliability of 1-, 3-, 5- and 10-plants per beat bucket sample varied with predator group, but multiple plant sample units were more cost-reliable than the one plant sample unit. Sample plans for the beat bucket method were developed for Orius adults, Orius nymphs, spiders, and adult Coccinellidae and the sum of these groups using the 3-, 5- and 10-plant sample unit sizes. A sample plan for estimating 0.75 predators per cotton plant required 24, 22 and 12 beat bucket samples and a sampling cost of 28, 39 and 27 minutes for the 3-, 5- and 10- plant sample unit sizes, respectively. The greater cost-reliability of the beat bucket sampling method and its ease of use is of particular advantage in assessing predator densities in a commercial cotton field monitoring program.

Last Modified: 12/24/2014
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