First Nearctic record of the swede midge (Diptera: Cecidomyiidae), a pest of cruciferous crops from Europe

Abstract

In 1996, damage symptoms typical of the swede midge, Contarinia nasturtii (Keiffer), were observed on broccoli, Brassica oleracea L. var. italica (Brassicaceae), crops east of Toronto, Ontario. Early attempts to identify an associated insect larva were unsuccessful, and damage symptoms became mistakenly attributed to nutrient deficiencies (T Clarke, personal communication). Between 1996 and 1999, damaged plants were seen by growers regularly, and resulted in up to 85% loss of marketable yield (T Clarke, personal communication). In June 2000, we initiated investigations at two sites 12 km apart to determine the causal organism of this damage. Both sites were located at farms where cole crops are primarily -gown and from where the first damage reports originated.