Dynamic spatial structure in the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

Integrating GPS with visual canopy surveys, a 1-m sampling support was used to explore within-field spatial organization of the Colorado potato beetle, Leptinotarsa decemlineata (Say), in potatoes (Solanum tuberosum (L.)). Georeferenced adult and large larvae counts were made in four ∼1.5 ha untreated potato fields during two seasons. Overwintered, immigrating adults established mean density trends, but spatial dependency (covariance structure) was not detected. Large larvae and F1 adults, in contrast, displayed covariance structure, accounting for up to ∼45% of the variation. Spatial patterns were related to population phenology, density, and mean density trends established during immigration.; The stability of these patterns was tested in fields treated with a narrow perimeter (5.5 m) of systemic imidacloprid and in fields where all rows received the systemic. Perimeter treatment reduced mean densities with no effect on phenology. Immigrating adults established similar trends in both treatments, but F1 larval trends of the Perimeter treatments diverged from immigrant patterns. Immigrating adults had little to no spatial dependence (covariance structure), while covariance structure of F1 larval and F1 adult populations developed as density increased in both treatments. Yields increased at a proportion higher than the proportion of land area treated, but remained lower than the Whole-field treatment. Refinement of border width is discussed to optimize trade-offs between yield, quality, and long-term maintenance of susceptibility.; To optimize perimeter width, locations of individual L. decemlineata overwintered adults were georeferenced within 24 hours of their immigration into a potato field in two field seasons. Distance was measured to the nearest field edge or to the field edge along a radial vector from the field center. The frequency of beetles captured within 1-m distance intervals was modeled as an exponential decay function of distance from the edge for both measurement methods.; A spatially-explicit individual-based simulation model of L. decemlineata population dynamics was developed to express the spatial patterns modeled in the field studies, and the immigration phase implemented. This will enable development and simulation tests of hypotheses related to the influence of scale upon the spatial dynamics of L. decemlineata , and the interaction of spatially variable management and scale.