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United States Department of Agriculture

Agricultural Research Service

Title: Estimating Populations of Aphidophagous Coccinellidae (Coleoptera) in Winter Wheat (Change Title, Add Authors, Add Accept Date)

Authors
item Michels, Gerald - TEXAS A&M UNIVERSITY
item Elliott, Norman
item Romero, R - TEXAS A&M UNIV
item French, Bryan

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 14, 1996
Publication Date: N/A

Interpretive Summary: The importance of coccinellids in the biological control of aphid pests in wheat fields in the Great Plains of the United States has been established. Efficient (low-cost and accurate) sampling methods for coccinellids are needed for use in integrated pest management (IPM) research and decision- making. Our objective was to compare several sampling methods to determine which are best for sampling adult and larval coccinellids. Removal samplin provided accurate estimates of population density for adults of most species, but consistently underestimated larval density. Timed count samples and sweepnet samples were significantly correlated with absolute density of both larval and adult coccinellids. Regression models were developed to convert estimates of abundance obtained using the most time efficient methods to estimates of population density. The models accounted for between 89 and 93% of the variation in the data. Sweepnet sampling was the most efficient method for estimating adult coccinellid density. Sweepnet and timed count sampling were equally efficient for sampling larvae. The methods developed in this study may prove useful in developing improved IPM practices for aphids in winter wheat.

Technical Abstract: Precise, yet efficient sampling methods for coccinellids are needed for use in IPM research and decision-making in winter wheat. Our objectives were to compare removal sampling with quadrat sampling to determine if removal sampling provided useful estimates of population density of adult and larval coccinellids in winter wheat, and to determine the utility of timed count sampling and sweepnet sampling for estimating adult and larval coccinellid densities. Removal sampling provided accurate estimates of population density for adults of most species, but consistently underestimated larval density. Timed count samples and sweepnet samples were significantly correlated with absolute density of both larval and adult coccinellids. Regression models were developed for converting relative to absolute density. Coefficients of multiple determination of regression models ranged from 0.89 to 0.93. Sweepnet sampling was more efficient (greater statistical precision per unit effort) than timed count quadrat, or removal sampling for estimating adult coccinellid density. Sweepnet and timed count sampling were equally efficient for sampling larvae and were significantly more efficient that quadrat and removal sampling.

Last Modified: 11/24/2014