Insect Community and Control of Phyllonorycter ringoniella by Parasitoid Wasps in a Natural Apple Orchard

In spite of no application of any pesticide and fungicides for more than 30 years, the apple farm of Akinori Kimura (AK farm) have yielded high quality apples as much as 20t ha-1. In order to clarify why insect pests are controlled in this apple farm without any pesticides, we compared insect communities between the AK farm and nearby conventional apple farm, and examined parasitic rate of a leaf miner larva (Phyllonorycter ringoniella) by parasitoid wasps. The AK farm had more heterogeneous and five-times more abundant insect community than the conventional farm. P. ringoniella invaded 68.5% of leaves but 42% of the larva were infected by wasps. These results suggest that top-down effects by natural enemies play important roles in preventing damages by insect pests in the AK farm