Testing for a trap: Variation in swede midge host preference among Brassica cultivars

The swede midge, Contarinia nasturtii Kieffer, is a gall-forming insect pest species of cruciferous plants. Historically distributed throughout Europe and southwestern Asia, the first documented reports of swede midge infestations within North America occurred during the early 2000s in Ontario, Canada (Chen et al., 2011; Hallett, 2007). Following its arrival, the midge is expanding its distribution eastward and southward, and currently inhabits farming regions within Quebec (CA), New York, and much of Northern New England (Chen et al., 2011). As an oligophagous pest of the family Brassicaceae (Chen et al., 2011; Hallett, 2007) the midge is particularly problematic in cooler temperate regions where brassica crop production constitutes a valuable portion of the local fresh vegetable market. In response to years long communications with Vermont growers detailing consistent variation in swede midge damage among kale varieties, our research team conducted research trials for the last two seasons assessing swede midge preference among four commonly planted kale varieties. After documenting significant variation among kale varieties, where red Russian kale (displayed significantly higher incidence ( >75%) of damage, we extended our investigation to include heading brassicas (e.g. cauliflower, broccoli, etc.) and other leafy varieties (e.g. collards). Using a randomized complete block design, we tested the efficacy of red Russian kale as a potential swede midge trap crop for non-kale cultivars.