No abstract

Predatory gall midge Aphidoletes aphidimyza, which is used for augmentative biological control of aphids in greenhouses, take aphid honeydew as an energy source to survive. Currently Rhopalosiphum padi on barley plants and Melanaphis sacchari on sorghum plants are used as the banker plant systems for A. aphidimyza to control A. gossypii on eggplants in Japan. We analyzed the sugar components of three species aphid honeydew by HPLC. The major components of honeydew were sucrose, fructose and melezitose for A. gossypii, glucose and fructose for R. padi and glucose, fructose and melezitose for M sacchari. Two minor components for these three aphid species were maltose and trehalose. We investigated the influence of sugars including three aphid artificial honeydew, six sugar components of three species aphid honeydew and water on the longevity of unmated females and males of A. aphidimyza. Both females and males attained the longest lifespan on sucrose and artificial honeydew of A. gossypii. Mean longevities of both females and males were shortest when they were provided with only water. We conducted another experiment where a mated female was released in a cage with an eggplant seedling infested with A. gossypii and was fed with sucrose or only water. Number of eggs laid and survival of the female was examined every day. Females fed with sucrose lived significantly longer and laid more eggs in their lifetime than those with only water.