Effects of augmentative releases of eggs and larvae of the ladybird beetle, Adalia bipunctata, on the abundance of the rosy apple aphid, Dysaphis plantaginea, in organic apple orchards

摘要: The impact of augmentative releases larvae and eggs the indigenous ladybird beetle Adalia bipunctata (L.) (Coleoptera: Coccinellidae) against rosy apple aphid Dysaphis plantaginea Pass. (Homoptera: Aphididae), a major pest insect on trees, was assessed in field experiments Switzerland, during 1997. In first experiment, were released 3-year old trees infested with five aphids at four different predator-prey ratios (0:5, 1:5, 1:1, 5:1). second ratio 5:1 branches naturally aphids. both experiments, interaction ants taken into account done two times spring. results showed that an release significantly prevented build-up colonies D. plantaginea. Significant reductions numbers recorded highest ratios, 1:1 5:1. Larvae efficient just before flowering time when growers normally have to spray their trees. On where present A. less efficient. Effects bipunctata, however, reliable. At date (5 April), they did not hatch, probably as consequence bad weather conditions.