EFFECTS OF ROOT DAMAGE BY CABBAGE MAGGOT, DELIA-RADICUM (L) (DIPTERA, ANTHOMYIIDAE), ON YIELD OF CANOLA, BRASSICA-CAMPESTRIS L UNDER LABORATORY CONDITIONS

The effects of root damage by larval cabbage maggots, Delia radicum (L.), on yield of canola, Brassica campestris L., were examined in laboratory experiments. Inoculations of eggs or first-instar larvae resulted in significant root damage. Damage that exceeded 50% of taproot surface area resulted in fewer racemes, fewer productive seed pods on axillary racemes, lower total biomass, and reduced yield of seed. Despite the latter effect, damage that restricts the number of flowering racemes and induces abortion of seed on axillary racemes may increase the efficiency of yield in canola, which flowers indeterminately over a short growing season.