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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETICS AND EVOLUTION OF HOST SPECIFICITY OF INSECT BIOLOGICAL CONTROL AGENTS, EMPHASIZING APHIDS AND MOTHS

Location: Beneficial Insects Introduction Research

Title: Parasitism of soybean aphid by APHELINUS species on soybean susceptible versus resistant to the aphid

Authors
item Hopper, Keith
item Diers, Brian -

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 19, 2014
Publication Date: June 6, 2014
Citation: Hopper, K.R., Diers, B.W. 2014. Parasitism of soybean aphid by APHELINUS species on soybean susceptible versus resistant to the aphid. Biological Control. 76:101-106.

Interpretive Summary: The soybean aphid, APHIS GLYCINES, is native to Asia, but during the last decade it has invaded North America, where it has spread to most soybean growing regions and become the most important insect pest of soybean. Current control of soybean aphid relies primarily on insecticides, but alternatives to insecticidal control are being explored, especially host plant resistance and biological control introductions, which may interact positively or negatively. We tested whether soybean-aphid resistant soybean varieties affected parasitism of the soybean aphid by APHELINUS GLYCINIS, which is being introduced from China for biological control of soybean aphid, and APHELINUS CERTUS, also native to Asia but accidentally introduced into the USA. Two resistance genes reduced the number of soybean aphids parasitized by APHELINUS GLYCINIS. One resistance gene had no effect on parasitism by APHELINUS CERTUS, while the other resistance gene reduced parasitism. Despite the impacts of these resistant alleles, these wasps are nonetheless able to attack soybean aphid on resistant soybean, which means that they can still contribute effectively to the management of soybean aphid.

Technical Abstract: The soybean aphid, APHIS GLYCINES, is native to Asia, but during the last decade it has invaded North America, where it has spread to most soybean growing regions and become the most important insect pest of soybean. Current control of APHIS GLYCINES relies primarily on insecticides, but alternatives to insecticidal control are being explored, especially host plant resistance and biological control introductions, which may interact positively or negatively. Research on host plant resistance to APHIS GLYCINES has revealed six genes that affect resistance. We measured the impact of the two most studied resistance genes, Rag1 and Rag2, on two parasitoid species: APHELINUS GLYCINIS, a recently described species native to Asia, that is being introduced into the USA to control APHIS GLYCINES, and Aphelinus certus, also native to Asia but accidentally introduced into the USA. The presence of each resistant alleles reduced parasitism of APHIS GLYCINES by A. GLYCINIS, with each resistant allele causing a two-fold reduction in number of parasitized aphids. The resistance alleles did not affect adult emergence, sex ratio, or the size of A. GLYCINIS. For A. CERTUS, the Rag1 resistant allele had no effect on parasitism, while the Rag2 resistant allele reduced parasitism four-fold. On the other hand the Rag1 resistant allele increased the frequency of males among progeny and decreased female size of A. CERTUS. Despite the impacts of these resistant alleles, these parasitoids are nonetheless able to parasitize APHIS GLYCINES on resistant soybean, which means that they can still contribute effectively to the management of this aphid.

Last Modified: 9/21/2014
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