Accuracy and precision of four sampling methods for aphid natural enemies in sorghum

Authors: Elliott, Norman; HIYASHIDA, RAFAEL - Oklahoma State University; GILES, KRISTOPHER - Oklahoma State University; VASQUEZ, NINA - Oklahoma State University; Butler, Haley; HOBACK, WYATT - Oklahoma State University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Predatory arthropods and hymenopteran parasitoids forage for prey in grain sorghum fields in the U.S. Great Plains and play a role in biological control of key aphid pests of sorghum, the greenbug, Schizaphis graminum, and the sorghum aphid, Melanaphis sorghi. Several species of arthropod natural enemies of aphids occur in sorghum. Research is needed to understand their role in aphid biological control aso they can be used as a component of pest management decision making for aphids in sorghum. We undertook a study to evaluate four sampling methods, D-vac suction sampling, sweep net sampling, and counting aphid on plants. Two counting methods were used. The first was counting natural enemies on two leaves per sorghum plant for 54 plants. The second was to count natural enemies for a fixed amount of time while walking slowly along rows in the field. Overall, 2-leaf counts and timed counts were the best sampling methods for sampling aphid natural enemies in sorghum. The evaluation of sampling methods paves the way for research to elucidate the roles of natural enemies in aphid biological control for use in improved, knowledge-based, pest management programs in sorghum.

Technical Abstract: Predatory arthropods of several taxa and hymenopteran parasitoids inhabit grain sorghum, Sorghum bicolor (L.), fields in the U.S. Great Plains and play a role in biological control of key aphid pests of sorghum, the greenbug, Schizaphis graminum (Rondoni) and the sorghum aphid, Melanaphis sorghi (Theobald). Several species of arthropod natural enemies of aphids occur in sorghum including Syrphidae, Chrysopidae, Hemerobiidae, Coccinellidae, Anthocoridae, and Araneae. Aphid parasitoids are also present including Aphelinus nigritus Howard and Braconidae species predominantly Lysiphlebus testaceipes Cresson). Research is needed to understand their role in aphid biological control at a level that facilitates incorporating their role in pest management decision making for aphids in sorghum. We undertook a study to evaluate four sampling methods, D-vac suction sampling, sweep net sampling, and counting aphid on plants. Two counting methods were used. The first was counting natural enemies on two leaves per sorghum plant for 54 plants. The second was to count natural enemies for a fixed amount of time while walking slowly along rows in the field. We evaluated the statistical accuracy and precision of population estimates for samples obtained using each method. All four sampling methods had significant bias for at least some natural enemies. The bias was either positive or negative depending on the particular category or species of natural enemy. Timed counts and 2-leaf counts were biased for fewer natural enemies than sweep net and D-vac sampling. ). Statistical precision was measured by the coefficient of variation (CV) for each sampling method. Precision varied among categories or species of natural enemy, with no one method being most precise for sampling all categories or species. Overall, 2-leaf counts and timed counts were preferred sampling methods in terms of high precision and low bias for natural enemies in sorghum.