Monitoring Eastern flower thrips and soybean thrips (Thysanoptera: Thripidae) and the generalist predator, insidious flower bug (Hemiptera: Anthocoridae) in the American Midwest Suction Trap Network

Eastern flower thrips (Frankliniella tritici) and soybean thrips
(Neohydatothrips variabilis) are vectors of soybean vein necrosis virus
(SVNV) and have increased in importance since the detection of the SVNV in
2008 in Arkansas. Understanding the factors that influence the timing and
extent of these insects’ activity, along with their predators such as the
insidious flower bug (Orius insidiosus), could contribute to improved
management. Here, we compiled monitoring data between 2020-2023 from the
American Midwest Suction Trap Network and examined associations between
the timing of early and late activity, cumulative activity density,
weather, landscape composition, and host plant phenology. We found that
the activity of Eastern flower thrips began earlier, and insidious flower
bug activity occurred later when conditions were warmer. In contrast, the
activity of soybean thrips began earlier when there was higher edge
density in the landscape but was not coincident with the timing of soybean
bloom, suggesting an important role for non-crop host plants in early
activity of these insects. Despite becoming active later, soybean thrips
had greater cumulative activity density where it was warmer, a discordance
suggesting the importance of migration in their overall abundance. Suction
trap captures might therefore reflect the influences of local conditions
as well as migratory movements on soybean thrips activity. Soybean thrips
and insidious flower bug cumulative activity densities were also found to
be positively correlated, suggesting that insidious flower bugs may be
opportunistically utilizing soybean thrips as prey. Continued regional
monitoring of these insects could be used to improve vector management.