The lack of natural antagonists frequently is the main reason for the buildup of large pest population densities. The goal of this study was the development of a device, which selectively permits parasitoids to emerge out of pest-infested plant material. The core of our prototypes is a mesh that allows passage of the smaller parasitoids, but retains the harmful hosts. We used our mass-hatching devices to separate horse chestnut leafminers, Cameraria ohridella (Lepidoptera, Gracillariidae), and their parasitoids. In Europe C. ohridella is a recently introduced pest of unknown origin, which frequently defoliates white flowering horse chestnut trees (Aesculus hippocastanum L., Hippocastanaceae) already in summer. Infested A. hippocastanum leaf litter was collected and stored in the mass-hatching devices. In 2002, the devices separated emerged parasitoids and moths very well; whereas more than 75 % of the 15’000 parasitoids passed the separator only 1 % of the 50’000 damaging leafminers overcame the barrier. This year, we refined the prototype and investigated the impact of exposed mass-hatching devices on parasitism rates of C. ohridella under natural conditions. Our devices may lead to a cost-effective biocontrol strategy against the horse chestnut leafminer. The use of mass-hatching devices should also be considered to control herbivore pests in other plant systems.
Species 1: Lepidoptera Gracillariidae Cameraria ohridella (horse chestnut leafminer)
Keywords: biological control, pest management
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