Soybean Thrips in Soybean
Crop Injury
Soybean thrips (Neohydatothrips variabilis) are one of several species of thrips found in soybean. Soybean thrips occur throughout the U.S., in southern Canada, and in Mexico. Both immature and adult thrips scrape leaf tissue and consume plant sap, usually on the underside of soybean leaves. Feeding results in tiny longitudinal scars along the leaf veins. Extensive feeding causes leaves to develop patches of silver, yellow, and bronze. Sustained feeding causes leaves to crinkle and die. Soybean thrips can transmit soybean vein necrosis virus (SVNV).
Thrips feeding and vein discoloration associated with soybean vein necrosis virus (SVNV).
Daren Mueller, Iowa State University.
Pest Description
The nymphs of soybean thrips are 1/32 inches long, slender, light green, and wingless. Adults are 1/16 inches long and are slender with black heads and fringed wings. They have distinct brown and cream bands on the abdomen.
Immature soybean thrips.
Adam Sisson, Iowa State University.
Mature soybean thrips.
Adam Sisson, Iowa State University.
Scouting
Soybean thrips tend to be more persistent in hot and dry weather. Start scouting at emergence and randomly select five areas of the field and examine 10 consecutive plants in each area. If plants are VE to V5, remove the lowest trifoliate on each plant and use a hand lens to count the number of thrips on the leaf underside. If plants are V6 or older, remove the fifth trifoliate from the uppermost node on each plant to make the counts. Determine the average number of thrips per trifoliate. Also estimate the percent of damage on each trifoliate. Consider the scars along the leaf veins and discolored or crinkled leaves on each trifoliate.
Management
Soybean thrips are rarely thought to be an economic issue in soybeans. However, insecticide thresholds exist. An example of an economic threshold is an average of eight thrips per leaf with 75% of the leaves exhibiting thrips injury. Please contact your local or state extension specialist for information on the most current management options.
Developed and reviewed by Carol Pilcher, Iowa State University and Robert Wright, University of Nebraska-Lincoln, with support from the United Soybean Board.
Thrips feeding and vein discoloration associated with soybean vein necrosis virus (SVNV). Daren Mueller, Iowa State University.
Immature soybean thrips. Adam Sisson, Iowa State University, Bugwood.org.
Mature soybean thrips Adam Sisson, Iowa State University.
Gallery images courtesy of Daren Mueller, Iowa State University; and Adam Sisson, Iowa State University.
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