Which traits of cabbage influence host-plant selection by the onion thrips (Thrips tabaci)?

Onion thrips have become a growing concern in cabbage production worldwide. Their damage on cabbage consists of bronze discoloration on white cabbage and raised bumps on red cabbage. Damage may appear many layers into the head and control by foliar insecticides has proven difficult. Resistant cultivars for some markets have been identified, but the mechanism(s) of resistance involved in this plant-pest interaction are not known. Our research efforts suggest that host selection preference of onion thrips at early head formation of cabbage has great influence on the extent of damage at harvest. Studies are underway to identify plant traits responsible for antixenotic and antibiotic resistance in cabbage. Our main focus has been to study the influence of plant volatiles and light reflectance of leaves. Additionally, we are exploring other plant characteristics including the thickness of the epidermal layer, plant waxes and the primary- and secondary plant metabolite content of cabbage leaves.