WHAT THE EVIDENCE SAYS
Perennial flower strips are intuitively attractive: more flowers, more arthropods, more natural enemies, fewer pests. Yet recent field work continues to show that the causal chain is unreliable. A Lower Saxony study found flower margins increased arthropod activity near edges, but spillover of natural enemies and pest-control benefits were limited and strongly taxon-dependent. Related Swedish work found flower strips clearly increased pollinators and several natural enemies while also increasing some herbivores—including pest thrips—and found no effect on aphid predation by leaf-dwelling predators.
WHY IT MATTERS / OUR READ
An intervention can successfully create habitat without successfully producing the management function for which it was installed. Measuring presence is not the same thing as measuring process.
CAVEATS / UNCERTAINTY
The results concern particular crops, sites and arthropod groups. Limited measured pest control does not negate the habitat or pollination benefits of flower strips.
SOURCE
Journal of Applied Ecology · Ohlendorf et al. · Germany
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Agriculture, Ecosystems & Environment · Rodríguez-Gasol et al. · Sweden
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