Researchers at the Tasmanian Institute of Agriculture are developing new approaches to conservation biological control in apple and pear orchards as part of an integrated pest and disease management strategy.
Conservation biological control focuses on supporting existing natural enemies rather than introducing exotic species. Beneficial insects commonly found in orchards include earwigs, lacewings, ladybird beetles, hoverflies, and parasitic wasps. These species rely on nectar and pollen to survive and reproduce, but conventional orchards often lack consistent food sources and are impacted by pesticide use.
By establishing flowering plants that provide nectar and pollen through the year, and placing them in areas protected from sprays, researchers aim to increase the presence and effectiveness of natural enemies against pests such as woolly apple aphid, spider mite, light brown apple moth, and codling moth.
Earlier trials within orchard interrows under the PIPS3 program delivered mixed results because native plants struggled to establish under high-traffic conditions and weed competition. The current PIPS 4 Profit Pest and Disease Management project is following recommendations from PIPS3 by shifting plantings outside main production zones and redesigning habitats to be more resilient.
The updated approach includes locating conservation strips away from machinery and spray exposure and using larger native plant species that can compete with weeds, provide more nectar and pollen, and offer shelter and structural support for beneficial insects.
Four orchards in the Huonville region now host trial sites, each with a 3 metre by 15 metre conservation strip positioned near production blocks. These strips are planted with a mixture of Tasmanian native species selected for staggered flowering times and suitability to local conditions. Data will be collected on the abundance and movement of natural enemies and how far their activity extends into surrounding apple blocks. Control areas consisting of standard grass strips are used for comparison.
Although the species list was designed for the Huon Valley, the broader selection principles apply elsewhere: matching plants to local climate, ensuring sequential flowering, and incorporating diverse plant structures. Growers in other regions are encouraged to select species using these criteria.
In addition to the conservation strips, researchers are evaluating no-mow areas, where grassy zones are left unmown or mown less frequently, particularly in spring. Allowing grasses such as dandelions to flower provides additional pollen and nectar for beneficial insects.
The conservation trials form part of the national PIPS 4 Profit program, which also includes work on biological control of codling moth using the parasitoid Mastrus ridens. These initiatives aim to support a more ecological approach to orchard pest management as growers respond to rising input costs and climate-related pressures.
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