LABORATORY BIOASSAY TO ASSESS BRASSICA SPP. GERMPLASM FOR RESISTANCE TO THE CABBAGE SEEDPOD WEEVIL (COLEOPTERA, CURCULIONIDAE)

A laboratory ovipositional bioassay was developed to assess Brassica ( Brassicaceae) germplasm for resistance, specifically antixenosis, to t he cabbage seedpod weevil, Ceutorhynchus assimilis (Paykull). The effe cts of seedpod excision, cage size, seedpod length, weevil collection dates, male presence, seedpod to weevil ratios, and weevil preconditio ning on C. assimilis ovipositional performance were evaluated. Standar dized protocols were then used to assess the acceptability of Brassica napus L. and B. rapa L. germplasm to the weevil. Paired choice tests using B. napus as a standard ('Bridger') identified 1 resistant line, PI 176876 (B. rapa), and 2 susceptible lines, PI 469918 and PI 469849 (B. napus). These tests also confirmed that adult feeding punctures ar e not correlated with oviposition. In all cases, ovipositional prefere nce was less pronounced in no-choice tests than in the paired choice t ests. Results of 6 x 6 choice tests were consistent with the paired ch oice tests in assessing ovipositional preference.