Evaluation of sampling methodology for determining the phenology, relativedensity, and dispersion of western flower thrips (Thysanoptera : Thripidae) in nectarine orchards

Western newer thrips, Frankliniella occidentalis (Pergande), cause serious economic damage to nectarines in the Okanagan and Similkameen Valleys, Brit ish Columbia, Canada. We evaluated several sampling methods for western flo wer thrips for their precision and ability to predict general population tr ends. Beating of branches, flicking of buds, and visual estimation methods were not accurate for estimating numbers of thrips in nectarine buds. Thrip s caught on sticky cards indicated general population trends, but were less efficient than collecting nectarine buds: and counting thrips. Searching f or thrips from buds in the field underestimated the density of both adults and larvae. and for adults, underestimated the proportion of the pale morph of western newer thrips. Dispersion patterns of thrips populations among o rchards were either random or aggregated dependent on the development stage of the nectarine buds.