Metapopulation approach for landscape level management of western tarnished plant bug, Lygus hesperus, in Texas (Hemiptera, Miridae)

Insect source-sink dynamics are vital to ecologically intensive pest management. Maintaining sink plant hosts, or "trap crops", and destroying alternate hosts or breeding places adjacent to the field crop are effective pest management strategies for some arthropods. However, determining whether a host acts as a source or a sink is challenging, especially when the pest species is highly mobile and polyphagous. The western tarnished plant bug, Lygus hesperus, is highly polyphagous, and can utilize >300 hosts. Its presence has been documented in 26 roadside weed hosts in the Texas High Plains. Previous studies demonstrated that L. hesperus prefer alfalfa over cotton and several alternate weed hosts. A four-year project involved surveying and sampling for L. hesperus in the agricultural landscapes of several sub-regions of the southwestern United States, including the Texas High Plains. In Texas, geographic information of the landscape vegetation complex was compiled from a 150 km radius in the Texas High Plains. In one study, fifty irrigated cotton fields representing the crop diversity within this region were sampled via sweep-net for 10 weeks. This effort also included sampling of up to six non-cotton insect habitats within a 3 km radius of each field. Seasonal average L. hesperus abundance data were regressed with 27 field characteristics (variables), including habitat-specific land cover, distance between focal cotton fields and non-cotton habitats, longitude, latitude, elevation, habitat heterogeneity index, and several environmental/ecological variables. Significant variables were selected using a stepwise regression at 15% probability rate. A 10-parameter linear model explained 93% of the variation in the data. Major parameters contributing significantly to variation in L. hesperus abundance in cotton were corn and sunflower acreages, focal cotton field distances from several non-cotton hosts, and habitat heterogeneity index. In addition, field marking-and-capture studies were conducted using protein markers and enzyme-linked immunosorbent assays to characterize L. hesperus intercrop movement behavior. The field marking-and-capture approach can be used to study the effects of various crop management practices on L. hesperus intercrop movement and can potentially be applied to other pests and cropping systems.