Threecornered Alfalfa Hopper in Soybean
Crop Damage
Threecornered alfalfa hopper (Spissistilus festinus) occurs throughout the southern United States, particularly in the Gulf Coast and South Atlantic states. Although typically considered a southern pest, it can occur sporadically in Midwestern soybean production regions and may cause significant injury under favorable conditions.
Both nymphs and adults feed on plant sap using piercing-sucking mouthparts. Older nymphs characteristically girdle soybean stems by creating a series of punctures around the stem. Girdled stems become weakened, brittle, and more susceptible to lodging or breakage. If plants survive the initial injury, nymphs may move upward and create additional girdles on the same plant.
Nymphs and adults also feed on petioles, nodes, peduncles, and developing pods. Adult females cause additional injury by inserting eggs into plant tissue. Early in the season, eggs are deposited near the base of the stem, whereas later generations deposit eggs in terminal and nodal tissues.
Threecornered alfalfa hopper damage-field view.
Ben Thrash, University of Arkansas.
Pest Description
Adult threecornered alfalfa hoppers are approximately 1/4 inch long, bright green, and have a distinctive triangular pronotum that extends over the body. Males often have orange to red markings along the edges of the pronotum. Young nymphs are straw-colored and covered with small spines. As they develop, nymphs gradually become green, the spines become more branched and conspicuous, and a characteristic tail-like extension forms at the end of the abdomen.
Adult threecornered alfalfa hopper (female).
Clemson University-USDA Cooperative Extension, Bugwood.org.
Scouting and Management
Fields that are planted late, have reduced tillage, contain crop residue, or are bordered by weedy areas may be at greater risk for threecornered alfalfa hopper infestations. Because this insect also feeds on alfalfa, adults may move into soybean fields following nearby alfalfa harvest. Begin scouting vegetative-stage soybeans shortly after plant emergence. Randomly examine one-foot sections of row throughout the field and record the number of plants infested with nymphs or adults, as well as the number of plants exhibiting girdling injury. Consider treatment when 10% of plants are infested or when 50% of plants show girdling. In reproductive-stage soybeans, use a sweep net to sample populations. Take 25 sweeps in each of four representative locations within the field. Consider treatment when populations average one hopper per sweep.
Where threecornered alfalfa hopper is a recurring pest, cultural practices such as adjusting planting dates, managing weeds along field borders, and modifying tillage practices may help reduce future infestations.
Developed and reviewed by Carol Pilcher, Iowa State University and Robert Wright, University of Nebraska-Lincoln, with support from the United Soybean Board.
Threecornered alfalfa hopper damage-field view. Ben Thrash, University of Arkansas.
Adult threecornered alfalfa hopper (female). Clemson University-USDA Cooperative Extension, Bugwood.org.
Threecornered alfalfa hopper nymph. Ed Beeson.
Adult threecornered alfalfa hopper (male) with red markings along the edges of the pronotum. Johnny N Dell, Bugwood.org.
Threecornered alfalfa hopper representative injury to stem (peanut plants). John French, Auburn University, Clemson University, University of Missouri, Bugwood.org.
Threecornered alfalfa hopper girdling and broken stems in soybeans. Ben Thrash, University of Arkansas.
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