Effects of host plant and soil moisture on the population growth of the bird cherry-oat aphid Rhopalosiphum padi (L.) using “banker-plant” strategies

Abstract

For biological control of aphids in greenhouses using “banker-plant” strategies, we compared the population growth of the bird cherry-oat aphid Rhopalosiphum padi (L.) on different gramineous grasses under different soil moisture conditions as follows. Experiment 1: eight species, including oat Avena sativa L. ‘Hayoat’, wheat Triticum aestivum L. ‘Satonosora’, barley Hordeum vulgare L. ‘Temairazu’, and rye Secale cereale L. ‘007’, were planted in three soil moistures (pF = 1.8, 2.0, and 2.2) in the commercial greenhouses of sweet pepper. Experiment 2: to clarify the effect of soil moisture on the population growth of aphids, the same grasses as above were planted under different soil moisture conditions (pF = 1.8 and 2.3) in experimental small greenhouses. The numbers of aphids were compared among the host plants and soil moisture conditions in both experiments. In the commercial greenhouses in Experiment 1, soil moisture significantly affected the number of aphids. However, soil moisture did not significantly affect the number of aphids in Experiment 2. Thus, we could not explain the differences in the population growth of aphids by soil moisture. The species of grass significantly affected the population growth of the aphids, suggesting oat, wheat, and rye were useful host plants for “banker-plant” strategies.