Impact of Reduced-Risk Insecticides on Soybean Aphid and Associated Natural Enemies
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The Department of Entomology seeks to teach the study of insects, their life-cycles, and the practicalities in dealing with them, for use in the fields of business, industry, education, and public health. The study of entomology can be applied towards evolution and ecological sciences, and insects’ relationships with other organisms & humans, or towards an agricultural or horticultural focus, focusing more on pest-control and management.
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The Department of Entomology was founded in 1975 as a result of the division of the Department of Zoology and Entomology.
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- College of Agriculture and Life Sciences (parent college)
- Department of Zoology and Entomology (predecessor, 1975)
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Abstract
Insect predators in North America suppress Aphis glycinesMatsumura (Hemiptera: Aphididae) populations; however, insecticides are required when populations reach economically damaging levels. Currently, insecticides used to manage A. glycines are broad-spectrum (pyrethroids and organophosphates), and probably reduce beneficial insect abundance in soybean, Glycine max (L.) Merr. Our goal was to determine whether insecticides considered reduced-risk by the Environmental Protection Agency could protect soybean yield from A. glycines herbivory while having a limited impact on the aphid's natural enemies. We compared three insecticides (imidacloprid, thiamethoxam, and pymetrozine,) to a broad-spectrum insecticide (λ-cyhalothrin) and an untreated control using two application methods. We applied neonicotinoid insecticides to seeds (imidacloprid and thiamethoxam) as well as foliage (imidacloprid); pymetrozine and λ-cyhalothrin were applied only to foliage. Foliage-applied insecticides had lower A. glycines populations and higher yields than the seed-applied insecticides. Among foliage-applied insecticides, pymetrozine and imidacloprid had an intermediate level of A. glycines population and yield protection compared with λ-cyhalothrin and the untreated control. We monitored natural enemies with yellow sticky cards, sweep-nets, and direct observation. Before foliar insecticides were applied (i.e., before aphid populations developed) seed treatments had no observable effect on the abundance of natural enemies. After foliar insecticides were applied, differences in natural enemy abundance were observed when sampled with sweep-nets and direct observation but not with yellow sticky cards. Based on the first two sampling methods, pymetrozine and the foliage-applied imidacloprid had intermediate abundances of natural enemies compared with the untreated control and λ-cyhalothrin.
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This article is from Journal of Economic Entomology 102(5):1816-1826. 2009
doi: 10.1603/029.102.0512