Effect of Roadside Alfalfa Mowing On the Abundance of Lygus hesperus in Adjacent Cotton Field: A Field Marking Study

Quantification of intercrop movement of Lygus hesperus between roadside alfalfa and an adjacent cotton field is not possible by indirect sampling methods such as sweepnet or drop-cloth. During 2007, a field marking and capture study was conducted at four selected sites in Lubbock County, Texas to quantify the movement of L. hesperus from roadside alfalfa into neighboring cotton and also to characterize the in situ host preference behavior of L. hesperus. Field marking of roadside alfalfa was accomplished by spraying the plants with a 10% chicken egg albumin protein solution (ca. 25 gal/acre) 24 h prior to mowing. Adult Lygus samples were collected from adjacent cotton and unmowed alfalfa by sweep sampling 24 h after the alfalfa was mowed. The movement of L. hesperus was inferred by detection of the marker protein in collected Lygus specimens by direct ELISA in the laboratory. When the action of mowing forced Lygus to move and seek a new habitat, a significantly greater number of Lygus moved to adjacent undisturbed alfalfa (69% at cotton blooming stage and 83% in boll maturation stage) compared with that detected in cotton. A numerically greater number of Lygus moved to cotton at blooming (31%) compared to that in the boll maturation stage (17%), indicating that the flowering stage is relatively more attractive for dispersing Lygus. Because unmowed alfalfa attracted and retained a greater number of L. hesperus compared to neighboring cotton, when both habitats were adjacent to the Lygus dispersing source, strip mowing of roadside alfalfa may reduce the movement of L. hesperus into cotton.