Population dynamics of western flower thrips (Thysanoptera : Thripidae) innectarine orchards in British Columbia

Development. of a control strategy for thrips attacking nectarine trees dep ends on an understanding of their phenology, distribution, and life history as related to characteristics of nectarine orchards. To this end, we compa red the overwintering behavior, distribution, and abundance of western newe r thrips, Frankliniella occidentalis (Pergande), among 11 nectarine orchard s located in the dry central interior of British Columbia, Canada, during 1 993 and 1994. Western newer thrips emerged from areas not previously used f or agriculture (wild areas) and from within orchards before trees were out of dormancy. Flight of thrips within and around orchards peaked during earl y bud development, with a second major peak several weeks later after husk fall as the next generation emerged. Orchards protected from wild areas by other orchards had the lowest densities of thrips in buds. Density estimate s of western newer thrips on trees were not affected by location of trees w ithin orchards or buds within trees, but most thrips were found in the most developed buds on a tree at any one time. Thrips were not found within bud s until petal was first visible on the buds. Larval feeding on buds at earl y petal Fall resulted in serious surface russetting of fruit.