| Effective management of polyphagous, highly mobile agricultural pests must be done at the landscape level. The distribution of pests across the agricultural landscape is largely dictated by two factors, the dispersal ability of both the pest and its predators and the distribution and suitability of host patches. We explored these factors to understand the spatial distribution and population dynamics of Lygus spp. (specifically L. hesperus and L. elisus). First, the dispersal ability of Lygus relative to that of its predators was investigated directly with a large-scale mark-capture study using protein markers. The results of this study indicate that Lygus exhibited intermediate dispersal abilities compared to its complex of generalist predators. This suggests that the reason why Lygus are under poor biological control is not because they out-disperse their predators. In this study we used a novel marking technique, the aerial application of protein markers. In protein marking studies, a threshold is set by the researcher to determine whether samples are marked. The conventional method for setting a threshold resulted in too high a misclassification rate to be confident in the results generated in long-distance dispersal studies, such as performed here. As a result, we developed new analytical methods that allowed for the analysis of rare dispersal events over large areas. Finally, we evaluated the effect of landscape structure on the population dynamics of Lygus hesperus . We used a novel data set to investigate the effect of 15 common crops and uncultivated agricultural land on Lygus density, correlating the amount of area of each crop type with Lygus densities measured in focal cotton fields. The results of this study support the already established importance of safflower, alfalfa, cotton, and uncultivated agricultural land on Lygus population dynamics. It also demonstrated the importance of several other crops in California's San Joaquin Valley that have not traditionally been considered for the management of Lygus. |
