Dispersal and abundance of Lygus hesperus in field crops

To predict Lygus hesperus Knight population dynamics in the field, a quantitative understanding of dispersal is needed. L. hesperus is a major pest of cotton and other seed crops in the San Joaquin Valley. Mark recapture experiments were performed that measured movement and abundance of L. hesperus in cotton (Gossypium hirsutum. L.), alfalfa (Medicago sativa L.), and blackeye bean (Vigna sinensis L.). Male L. hesperus moved farther than females (4.6 versus 3.6 m/d). Movement was greater in the east-west axis than the north-south axis (7.0 versus 2.4 m/d). Calculations based on mark-recapture data suggest that a random walk model describes L. hesperus dispersal well. Diffusion estimates predict 98% movement radiuses in cotton, alfalfa, and bean as 15.6, 14.4, and 7.3 m/d, respectively. Estimates of absolute L. hesperus abundance were 45,000/ha in alfalfa during the August peak, approximately five times those in cotton. The results Suggest that management of L. hesperus may be affected by greater dispersal along the east-west axis and the strong male bias in sweep-net samples.