Authors: Gary L. Hein & Frank B. Peairs[1]
Two aphid species are found in dry beans in the High Plains. Bean aphid (Figure 1) transmits Bean Common Mosaic Virus and Bean Yellow Mosaic Virus, but populations rarely reach economically significant levels. Soybean aphid (Figure 2) is a recent arrival to the region. It does not directly damage dry beans but can transmit certain viruses. Fortunately, most dry bean classes grown in the High Plains have significant resistance to these diseases.
Identification (and life cycle/seasonal history)
Bean aphid, Aphis fabae Scopoli, is found in both winged and wingless forms on the undersides of leaves and on stems of the bean plant. The aphids are blue-black in color and overwinter in the egg stage on Euonymus plants. They move to dry bean and other summer hosts after a spring generation on its overwintering host.
Soybean aphid, Aphis glycines Matsumura, (SBA) is a small pale yellow aphid found in both winged and wingless, although most of SBA on dry beans should be winged. It overwinters on buckthorn. After several spring generations on buckthorn, they disperse to soybean or, much less commonly, to dry beans or other legumes. It will go through up to 15 asexual generations (females only, giving birth to live young) on soybean before returning to buckthorn to lay overwintering eggs. Until recently, the soybean aphid was found mainly in the north central states, Asia, and Australia. More recently it has spread into the High Plains.
Plant Response and Damage
The bean aphid is a known vector of Bean Common Mosaic Virus and Bean Yellow Mosaic Virus. Severe infestations can cause wilting and discoloration, but naturally occurring biological controls normally prevent this.
Soybean aphid feeding damage is of little concern to dry beans because dry bean is a poor host and aphid survival is low. However, the soybean aphid is a good vector of Bean Common Mosaic Virus. Symptoms vary with dry bean variety and virus strain and can include mosaic patterns on leaves, leaf deformation, veinal necrosis and lesions in leaves. Crop yield losses can be substantial if the plant is infected early. However, important market classes, including as pintos and great northerns, have good resistance. Other classes, including kidneys, may be more susceptible.
Management Approaches
The bean aphid is not considered a serious pest and control generally is not considered necessary. The soybean aphid is pest but is not expected to be a major problem because it does poorly on dry beans, and, furthermore, good resistance to Bean Common Mosaic Virus is found in the market classes commonly grown in the region. If, however, soybean aphid becomes abundant regionally, susceptible market classes may require protection.
Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.
