Soybean aphid (Hemiptera: Aphididae) feeding behavior is largely unchanged by soybean mosaic virus but significantly altered by the beetle-transmitted bean pod mottle virus

Authors: Todd, Jane; Stewart, Lucy; Redinbaugh, Margaret; Wilson, Jennifer - Jenny

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2022
Publication Date: 5/15/2022
Citation: Todd, J.C., Stewart, L.R., Redinbaugh, M.G., Wilson, J.R. 2022. Soybean aphid (Hemiptera: Aphididae) feeding behavior is largely unchanged by soybean mosaic virus but significantly altered by the beetle-transmitted bean pod mottle virus. Journal of Economic Entomology. https://doi.org/10.1093/jee/toac060.
DOI: https://doi.org/10.1093/jee/toac060

Interpretive Summary: Soybean production in the US is threatened by an invasive sap-sucking insect, the soybean aphid. In addition to damage caused by feeding, this insect can also carry a number of plant viruses that can infect soybean, causing further damage. It has been previously shown that plant viruses can change the feeding behavior of their insect vectors. We wanted to see how soybean aphid feeding behavior was affected by two important viruses of soybean: a virus that the insect transmits, Soybean mosaic virus, and one that it does not, Bean pod mottle virus. Our surprising results revealed that the virus transmitted by the aphid does not cause any changes to aphid feeding behavior, but the other virus, which is transmitted by a different insect, a beetle, did. The beetle-transmitted virus caused the soybean aphid to struggle to find and enter the plant vascular system. However, the affected aphids were still able to eventually find the vasculature and drink the plant’s sap. These results show that the relationship between this invasive insect and plant viruses is quite complicated and may affect insect populations and virus transmission in soybean fields. This information is helpful for scientists trying to understand the complex relationships between plant viruses and their vectors and can be used by scientists to develop new ways to manage virus and insect pests to help soybean growers.

Technical Abstract: The soybean aphid (Aphis glycines Matsumura) is an economically important invasive pest of soybean. In addition to damage caused by soybean aphid feeding on the phloem sap, this insect also transmits many plant viruses, including Soybean mosaic virus (SMV). Previous work has shown that plant viruses can change plant host phenotypes to alter the behavior of their insect vectors to promote virus spread, known as the vector manipulation hypothesis. In this study, we used electropenetography (EPG) to examine the effects of two plant viruses on soybean aphid feeding behavior: SMV, which is transmitted by many aphid species including the soybean aphid, and Bean pod mottle virus (BPMV), which is transmitted by chrysomelid and some coccinellid beetles but not aphids. These two viruses often co-occur in soybean production and can act synergistically. Surprisingly, our results showed little to no effect of SMV on soybean aphid feeding behavior but profound differences were observed in aphids feeding on BPMV-infected plants. BPMV-exposed aphids took longer to find the vascular bundle, and once there, spent more of their time preparing the phloem than ingesting sap. These aphids also ingested more xylem. Interestingly, the observed alterations in BPMV-exposed aphid feeding behavior resembles that of aphids feeding on insect-resistant soybean plants. The cause of this alteration in feeding behavior is not known, but potential implications for virus transmission and soybean aphid populations are discussed.