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Providing evidence to improve practice

Individual study: Impact of wildflower strips on biological control of cabbage lepidopterans.

Published source details

Pfiffner L., Luka H., Schlatter C., Juen A. & Traugott M. (2009) Impact of wildflower strips on biological control of cabbage lepidopterans. Agriculture, Ecosystems & Environment, 129, 310-314

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Plant nectar flower mixture/wildflower strips Farmland Conservation

A replicated, controlled study in the summers of 2004-2005 in northwest Switzerland (Pfiffner et al. 2009) found wildflower strips had a variable effect on parasitism and predation of eggs and larvae of two common butterfly/moth (Lepidoptera) cabbage pests. Parasitization rates of cabbage moth Mamestra brassicae eggs and larvae as well as small white butterfly Pieris rapae larvae on one farm did not differ between plots with and without wildflower strips. However on a second farm, parasitization rates of small white butterfly larvae and predation rates of cabbage moth eggs were significantly higher in plots with adjacent wildflower strips. Wildflower strips did not affect the spatial pattern of parasitization in the fields. Six cabbage Brassica oleracea fields were studied on two organic farms. Two blocks (45 x 25 m) were studied on each field, one with and one without a wildflower strip (3 x 35 m). Wildflower strips were sown with seed mixtures containing 24 native plant species, and were not treated with pesticides or mown. Egg parasitization rates were assessed by placing laboratory eggs pinned to paper cards on the ground underneath labelled plants in a 3 x 3 m grid for three days. Eggs were incubated for four weeks at 22°C to rear any parasitoids. Missing and damaged eggs were counted to estimate the predation rate. Butterfly larvae were sampled on randomly selected plants and parasitization rates were determined using DNA-based techniques.