COS 30-7 - Comparing the dispersal ability of an herbivore relative to its predators in an annual agroecosystem using a novel large-scale mark-capture technique

Tuesday, August 9, 2011: 10:10 AM
18C, Austin Convention Center
Frances S. Sivakoff, Department of Biology, North Carolina State University, Raleigh, NC, Jay A. Rosenheim, Department of Entomology, University of California, Davis, CA and James R. Hagler, USDA-ARS, Arid-Land Agricultural Research Center, Maricopa, AZ

In annual agroecosystems, staggered planting dates, pesticide treatments, and harvesting events create a “shifting mosaic” of habitats that necessitates frequent colonization and recolonization by herbivores and natural enemies. In these systems, herbivores are generally thought to have superior dispersal abilities to their predators and escape from biological control by colonizing the interior regions of large monocultures. In California’s San Joaquin Valley, the generalist herbivore Lygus hesperus is under poor biological control despite a suite of known predators. One possible explanation is that L. hesperus has a greater dispersal ability than its predators. To examine this directly, we performed a multi-year, large-scale mark-capture study where we marked alfalfa fields containing L. hesperus and its predators with aerial applications of protein markers. Following marking, the field was harvested for hay by the grower, prompting a dispersal event. At several times following harvest, surrounding cotton fields were sampled at known distances from the marked field for L. hesperus and its predators. 


Contrary to the general view, our data do not suggest that Lygus routinely out-disperses its predator community. Instead, the dispersal ability of L. hesperus fell near the average dispersal ability of its predators. Implications for predator-prey population dynamics and biological control will be discussed.

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