Factors affecting population dynamics of thrips vectors of soybean vein necrosis virus

Authors: KEOUGH, STACY - Indiana University-Purdue University; DANIELSON, JONATHAN - Indiana University-Purdue University; MARSHALL, JORDAN - Indiana University-Purdue University; Lagos-Kutz, Doris; VOEGTLIN, DAVID - University Of Illinois; SRINIVASAN, RAJAGOPALBABU - University Of Georgia; NACHAPPA, PUNYA - Indiana University-Purdue University

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2018
Publication Date: 3/1/2018
Citation: Keough, S., Danielson, J., Marshall, J.M., Lagos-Kutz, D.M., Voegtlin, D., Srinivasan, R., Nachappa, P. 2018. Factors affecting population dynamics of thrips vectors of soybean vein necrosis virus. Environmental Entomology. 47(3):734-740. https://doi.org/10.1093/ee/nvy021.
DOI: https://doi.org/10.1093/ee/nvy021

Interpretive Summary: Soybean is the second most important field crop in the United States. There are many pests that attack soybean including several species of thrips which are small nearly macroscopic insects that feed primarily on soybean leaves. In addition to direct damage to plants, the insect can transmit viruses that may detrimental to the plant. This includes a virus that was described in the last 10 years named soybean vein necrosis. In this study, thrips species were monitored in suction traps in 2013 and 2014. The type of thrips found were the soybean thrips, the flower thrips, and tobacco thrips. There was no gradient in thrips populations from southern to northern locations in Indiana suggesting that these insects are not migratory and may overwinter in soil or perennial non-crop host plants and other weed hosts in Indiana. Soybean vein necrosis virus was first detected in early August, which coincided with the peak of the primary vector soybean thrips. The virus was not detected earlier in the season despite peaks in flower thrips activity. These results may be used in weather-based models to predict both thrips dynamics as well as SVNV outbreaks. This information is important to soybean researchers in the private and public sectors and to other scientists working on thrip population dynamics in other crops.

Technical Abstract: Thrips-infesting soybeans were considered of minor economic importance, but recent evidence of their ability to transmit a newly identified soybean virus, Soybean vein necrosis virus (SVNV), has raised their profile as pests. Season-long surveys were conducted using suction traps to determine the effects of temperature and precipitation on the spatiotemporal patterns of three vector species of SVNV, Neohydatothrips variabilis (Beach) (Thysanoptera: Thripidae) (soybean thrips), Frankliniella tritici (Fitch) (Thysanoptera: Thripidae) (eastern flower thrips), and Frankliniella fusca (Hinds) (Thysanoptera: Thripidae) (tobacco thrips) in soybean fields in Indiana in 2013 and 2014. In addition, soybean fields were surveyed for presence of SVNV in both years. We found that the magnitude and timing of thrips activity varied greatly for the three species. N. variabilis activity peaked in mid-August each year. The peak activity for F. tritici occurred between late-June, and a second peak in activity was observed in early-August, while F. fusca activity remained more or less the same with no peak. There was no gradient in thrips populations from southern to northern locations. This suggests that these insects are not migratory and may overwinter in soil or perennial noncrop host plants and other weed hosts in Indiana. The capture rates of N. variabilis and F. tritici were only related to temperature, and capture rates of F. fusca were not related to either variable. SVNV was first detected in mid-late August, which coincided with the peak of the primary vector, N. variabilis. The virus was not detected earlier in the season despite peaks in F. tritici activity. Our results may be used in weather-based models to predict both thrips dynamics as well as SVNV outbreaks.