Individual study: Nettle strips have greater aphid and aphid predator diversity than adjacent arable fields in Gembloux, Belgium.
Alhmedi A., Haubruge E. & Bodson B. (2007) Aphidophagous guilds on nettle (Urtica dioica) strips close to fields of green pea, rape and wheat. Insect Science, 14, 419-424
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Plant nettle strips
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.