Individual study: Attractiveness of three weed species to polyphagous predators and their influence on aphid populations in adjacent lettuce cultivations
Sengonca C., Kranz J. & Blaeser P. (2002) Attractiveness of three weed species to polyphagous predators and their influence on aphid populations in adjacent lettuce cultivations. Anzeiger Fur Schadlingskunde-Journal of Pest Science, 75, 161-165
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Grow non-crop plants that produce chemicals that attract natural enemies
A controlled study in summer 2000 in Bonn, Germany (Sengonca et al. 2002) found that the abundance of four natural predators was significantly higher in lettuce Lactuca sativa plots intercropped with attractant plants (3.0-3.2 larvae and 3.2-3.6 adults per lettuce plant) than in monoculture lettuce plots (1.5 larvae and 1.7 adults). Egg and pupae abundance of the three ladybird species (Coccinellidae) and common green lacewing Chrysoperla carnea was similar between intercropped (12.5-13.0 eggs and 1.5-1.7 pupae per plant) and monoculture (11.5 eggs and 1 pupa) plots. Aphid (Aphidoidea) abundance was significantly lower in intercropped (110-125 per lettuce plant) than monoculture (160 per plant) plots. Natural predator and aphid numbers were similar between plots intercropped with wormwood Artemisia vulgaris, tansy Tanacetum vulgare or stinging nettle Urtica dioica. The attractant plants were tested separately in three blocks inside a 6 x 50 m field. Each attractant plant species was grown in nine plots of 1 x 0.3 m, placed in a 3 x 3 grid among 20 lettuce rows.