Modeling colonization of overwintered immigrant Leptinotarsa decemlineata (Coleoptera Chrysomelidae)

Colonization of potato (Solanum tuberosum [L.]) fields by Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), has often been recognized as a process that initially results in an edge-biased spatial pattern. We modeled this spatial process by measuring distance of immigration for individual overwintered adults. 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. Expression of the results as a cumulative frequency has management implications for spatial deployment of control measures against immigrating beetles and applicability for spatially explicit simulation of the within-field population dynamics of the beetle. Managers might use such models to estimate the proportion of immigrating adults that would be affected by border treatments of a plant systemic or transgenic insecticide as a function of the width of the treatment.