Injury to soybean seedlings from alfalfa weevil (Coleoptera: Curculionidae) larvae

Alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), is primarily a pest of alfalfa, but it has been reported feeding on other plants, including soybean. The relatively limited literature on H. postica in soybean indicates that adults and larvae can feed on soybean, but it is not suitable for larval development and survival. There have been instances of H. postica adults moving from alfalfa to nearby soybean fields where they have inflicted significant injury to the soybean plants. Here we report an instance of H. postica larvae causing severe feeding injury to soybean. This infestation of soybean was the result of a “green bridge” created by planting soybean into a field containing live alfalfa plants that were infested with H. postica larvae. After termination of the alfalfa in that field, H. postica larvae moved to and fed on soybean seedlings. The observations reported here provide evidence H. postica larvae can become pests of soybean intercropped (or relay planted) into alfalfa.