Colonization and Intraplant Distribution of Thrips tabaci (Thysanoptera: Thripidae) on Cabbage

Abstract

To examine temporal aspects of Thrips tabaci Lindeman, colonization of cabbage, uninfected cabbage plants were placed adjacent to wheat, oat, and alfalfa fields on a weekly basis from July to October during 1983 and 1984. These cabbage plants were colonized by T. tabaci, with highest oviposition coinciding with emigration of T. tabaci adults from the adjacent field or forage crop. To examine within-plant colonization of cabbage, plants were sampled for 20 consecutive weeks in 1982. Individual leaves were excised, washed in 70% ethanol to remove thrips, and the thrips were identified. Only T. tabaci colonized cabbage and, before head formation, T. tabaci adults were most commonly found on the developing meristem, while larvae were most abundant on frame leaves. Once head formation began, thrips populations increased rapidly within the head and remained high until harvest. T. tabaci larvae, pupae, and adults were found in the first 11 layers of mature heads.