Effects of Feeding by Threecornered Alfalfa Hopper Nymphs (Homoptera: Membracidae) on Hypocotyls of V1 and V3 Stage Soybean Plants1

Abstract

Hypocotyls of vegetative V1 and V3 stage soybean, Glycine max (L.) Merrill were subjected to feeding by third, fourth, and fifth instars of the threecornered alfalfa hopper, Spissistilus festinus (Say). Significant differences in feeding injury, plant responses, fresh and dry root weights, and plant stage development occurred due to fourth instar feeding on V1 stage plants. Most soybean plants responded to partial and complete girdles by producing swelling and/or adventitious roots above the girdle.

Soybean leaf responses to threecornered alfalfa hopper petiole girdling

“…Internally, the vascular bundles become disorganized (Mitchell & Newson, 1984), and cellular hyperplasia occurs, accompanied by a proliferation of secondary phloem surrounded by starch grain-containing cells (Johnson et al, 1988). Reports of other plant responses to girdling include yield responses of individual plants and plant stands (Tugwell et al, 1972;Mueller & Dumas, 1975;Mueller & Jones, 1983;Sparks & Newson, 1984;Sparks & Boethel, 1987), plant growth responses (Johnson & Mueller, 1989), effects on nitrogen fixation (Hicks et al, 1984), and effects on translocation (Hicks et al, 1984;Spurgeon & Mueller, 1991). Still, the relationships among the various responses and the implications of the responses to both the plant and the insect are poorly understood.…”