Its production is relatively new to the U.S., but quinoa has quickly expanded beyond Colorado, where it was first grown, to Idaho, Oregon, and Washington, for example. The expansion of quinoa acreage has been abruptly halted when a stem-boring insect has been discovered in quinoa in Colorado and neighboring states in 2021. The pest, an agromyzid fly, Amauromyza karli Hendel (Diptera: Agromyzidae) has either caused severe yield losses or destroyed the crop entirely. The pest has since been confirmed in quinoa in Idaho and Oregon. There are no recommendations for its management, and little is known about natural history traits of A. karli. The critical knowledge gaps we are working to address to effectively suppress this highly destructive pest include 1) establishing abundance patterns of A. karli in the field that can inform planting date modifications and timing of biological and chemical control, 2) knowledge of weeds that can serve as hosts to the fly to formulate recommendations for weed management that can effectively lower the risk and severity of infestations in quinoa; 3) evaluating integrated pest management tactics such as host plant resistance within existing quinoa varieties, biological control, and systemic insecticides; and 4) ensuring that the recommendations for management are widely shared with quinoa producers. This is a collaborative project with the Stewart Lab.
Adult A. karli collected from quinoa grown in Alamosa, Colorado. Distinguishing features include a yellow head and dark brown body with light-yellow halteres. The legs are dark brown with yellow ends of the femur and tibia. Image credit: Tim McNary, Colorado State University
Destruction of pith in quinoa stem caused by feeding of A. karli. Image credit: Ada Szczepaniec, Colorado State University
Exit hole in quinoa stem caused by A.karli. Image credit: Ada Szczepaniec, Colorado State University