Restoring ecological balance to orchard insect pest management

One approach to sustainable pest management is to optimize natural ecological balance through the development of greater functional biodiversity.  We have previously demonstrated the role of compost and companion plants in increasing biological control in orchards.  In this project we investigated the role of interplanting apple orchards with peach trees bearing extrafloral nectar glands.  The hypothesis was that by providing alternate food resources in the form of extrafloral nectar, natural enemies would be more effective in controlling pests.  Studies were conducted in research apple orchards that were not treated with insecticides; the orchard treatments were an apple monoculture, apple orchard interplanted with 9% peach trees, or apple orchard interplanted with 50% peach trees.  Peach trees used produced extrafloral nectar from glands at the base of the leaves throughout the time when fruit were present in the apple trees.  Biological control of rosy apple aphids prior to their migration to alternate hosts was significantly greater in the orchard with 9% peach trees than either the monoculture or 50% interplanted orchard.  In the 9% interplanted orchard, all colonies were eliminated before migration began, thus completely interrupting the life cycle of this pest.  Studies with spirea aphid also showed that there was greater biological control on apple trees adjacent to peach trees producing nectar than on apple trees more distant.  By interplanting apple orchards with 9% peach trees; along with companion plants, compost and specific targeted (e.g., pheromones or insect pathogens) tactics to control direct fruit feeding pests; sustainable pest management is possible.