Wildflower strips to reduce lepidopteran pests in cabbage crops

Vegetable production systems are highly intensive and the periodic cultivations lead to un-favourable conditions for natural enemies. Using non-crops it is possible to create ecological infra-structure offering suitable food for natural enemies, and shelter from adverse conditions. On four organic farms in Western-Switzerland, we have tested in cabbage crops if wildflower strips are an appropriate tool to reduce lepidopteran pests. Analyses of wildflower strips on parasitism of caterpillars of Pieris rapae and Mamestra brassicae indicated a pest control potential. Grid trial using reared egg batches revealed no significant effect on parasitism of exposed M. brassicae and Plutella xylostella eggs in relation to the distance of the strip.