Oilseed rape is affected by a complex of different crucifer pests. Cruciferous stem weevils
(Ceuthorhynchus spp.) are relatively new oilseed rape (Brassica napus L.) pests in Latvia. Although currently
brassica pest control is performed according to the appearance of first specimens of Ceutorhynchus or other
brassica pests, for a large number of insecticide treatments a positive biological efficiency is observed (however,
within a large range – 8–98%). The current application of brassica pest control may be described as preventive,
which is not permitted in the integrated pest management system. The present research estimates biological
efficiency and application time of synthetic pyrethroid (PIR) and combined pyrethroid+neonicotonoid
(PIR+NNI) to control winter oilseed rape pest species, as well as stimulates discussion about their use.
Evaluation of the monitoring data of Ceutorhynchus spp. showed that C. typhae and C. sulcicollis emerge first,
but damaging species C. pallidactylus – a week later. Consequently it is not only necessary to monitor the
weevils but also to identify their species in order to decide on the control measures. The combined PIR+NNI
insecticide proved to have the highest biological efficiency for cabbage stem weevil control. Both classes of
synthetic insecticides revealed a considerable biological efficiency for weevil control. The research suggests
that effectiveness of insecticide is affected by many factors: plant development stage during the spray, agroclimatic
conditions, spray quality, field location and size, distribution of pests, and crop rotation.
