The cabbage seedpod weevil, Ceutorhynchus obstrictus (Coleoptera: Curculionidae) - a review

The cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), which has recently become established in southern Alberta, is a serious pest of oilseed rape (Brassica napus L.) in Europe and the USA and poses a major threat to the economic sustainability of canola production in western Canada. This paper reviews the biology and control of this pest and identifies future research needs. Control strategies in Europe and the USA have so far relied on insecticides because no cultural or biological control methods have been successful. Research on plant resistance is in progress at several research centres and could provide the long term solution. Several parasitoid species are known to suppress populations of the weevil in Europe and are candidates for biocontrol programs in North America. Current research priorities in western Canada are to quantify the effects of weevil densities on canola seed yield, to establish economic thresholds and to design control strategies that integrate chemical, cultural and biological controls. Research programs should be established to screen a wide range of Brassica germplasm to identify sources of resistance for use in developing resistant cultivars for western Canada. Research on the overwintering ecology and seasonal activity of this weevil is needed to model how its range is likely to expand to other canola growing regions of Canada and to enable forecasting of outbreaks.Key words: Brassica, oilseed rape, Ceutorhynchinae, Ceutorhynchus assimilis, Ceutorhynchus obstrictus, canola insect pest