Action: Plant nettle strips
- A small study from Belgium found that planting nettle strips in the margins of three arable fields resulted in a higher number of aphid predator species. The number of aphid predators on a natural patch of nettles was higher than on crops, however there were fewer predators on nettle strips than on crops. Three insect families, including green lacewings, were only found on nettles.
In agricultural landscapes, field margins can provide valuable habitats for maintaining and enhancing biodiversity. The common nettle Urtica dioica is a perennial species that provides food for a range of insects (Greig-Smith 1948), including ‘beneficial’ species that help to suppress pests. This intervention involves planting nettle strips which may enhance invertebrate diversity on arable fields.
Greig-Smith P.W. (1948) Biological flora of the British Isles. Journal of Ecology, 36, 343-351.
Supporting evidence from individual studies
A small study in 2005 of six nettle Urtica dioica strips planted in the margins of three arable crops in Belgium (Alhmedi et al. 2007) found that planting nettles resulted in a higher number of aphid predator species. Numbers of aphid predator species tended to be higher on nettles (nettle strips: 6-9 species, natural nettle stand: 15) than crop plants (0-4 species). Predator abundance was significantly greater on the natural nettle stand (89 individuals) than wheat and pea crops (predators: 17-20). However predator abundance was lowest on nettle plots (predators: 6-14). Nine ladybird (Coccinellidae) species were observed on nettle, compared to six on crops. Ladybird and hoverfly (Syrphidae) abundance was highest on the natural nettle stand (62 ladybirds and 7 hoverflies), followed by wheat and pea crops (5-19 and 3-5 respectively) and lowest on nettle plots (3-9 and 0-1). Predatory minute pirate bugs (Anthocoridae), plant bugs (Miridae) and green lacewings (Chrysopidae) were only observed on nettle. Nettle strips were planted in two plots (10 x 20 m) in the margins of three arable fields, a nearby large natural nettle stand (1,000 m²) in a natural reserve was also sampled. Ten plants/plot were randomly selected each week to count and identify all aphid predator populations (May-August 2005). Larvae were collected and reared until emerged adults could be identified. Aphid data are not presented here.