Evaluation Of Intercrop Movement Of Lygus Between Cotton And Roadside Alfalfa

Lygus hesperus is an economically important insect pest of cotton in the Texas High Plains. Field surveys, cage studies, and protein marking and mark-release-recapture, Lygus movement, and alfalfa marking and mowing studies were conducted in Lubbock, Texas for three years. Objectives of these studies were to develop better techniques for quantification of intercrop movement of Lygus and characterize the intercrop movement behavior in alfalfa-cotton system. The sweepnet survey of Lygus in cotton field and adjacent roadside alfalfa showed that Lygus colonize in alfalfa in summer months and disperse into cotton and other hosts in July-August, with a significant negative correlation between Lygus population in alfalfa and cotton fields. Roadside alfalfa marking and mowing study showed that alfalfa mowing dispersed Lygus to adjacent unmowed alfalfa more than to adjacent cotton field. Alfalfa mowing height study showed that alfalfa mowed at 6” height retained 25% of resident Lygus in that mowed alfalfa patch, suggesting a greater affinity of Lygus to alfalfa than to cotton. Mark-release-recapture of Lygus bugs showed a two-directional movement between alfalfa and cotton, but the net movement was higher from alfalfa to cotton during cotton blooming stage. A controlled field cage protein marking study suggested that 72 h foraging time provides the most positively marked specimens in both cotton and alfalfa. Our study in alfalfa showed that 6% nonfat dairy milk resulted in highest (40%) positively marked Lygus while 4% egg white showed 90% of positively marked Lygus, suggesting that egg white may be superior field marking protein as compared with non fat dairy milk for Lygus in alfalfa. Information on intercrop movement behavior from this study are currently used in developing regional/landscape level pest management strategies for Lygus hesperus.