Managing flies for crop pollination (PH16002)
What’s it all about?
This investment is looking into the potential of using flies as alternative crop pollinators, including looking at the effectiveness of specific species in pollinating avocado, berry (blueberry, raspberry and strawberry), hybrid carrot seed and brassica seed crops. The work is part of the Hort Frontiers Pollination Fund, and includes funding from a range of sources, including through the Hort Innovation Avocado Fund.
Potential benefits of flies as alternate pollinators to bees include;
- Different fly species mean that flies can be present all year round
- Flies have high sugar demand and naturally visit flowers for nectar
- Flies are hairy and so can pick up and move pollen
- Flies can be readily mass-reared with reasonable minimal inputs and do not sting workers.
The project is first identifying the best candidate fly species for various crops via surveys of field populations of flies visiting crops at the time of flowering. Once the fly species and their crop preferences have been determined, the project will then focus on developing novel technologies to mass rear candidate fly species for use in horticultural settings.
The research team determined the developmental rates for at 1 species of fly being considered for commercialisation as a managed pollination agent, viz., Calliphora dubia. At 25°C, the development of larvae through to pupae on a rearing substrate took 11 days for completion. Adult emergence then took a further 6-7 days to complete, so that total development time from newly laid larvae to adult emergence was 17-18 days. Several different larval rearing substrates were also tested and showed that either 1) a blend of 70 per cent meatmeal, 20 per cent bran flakes and 10 per cent whole discarded eggs or 90 per cent meatmeal and 10 per cent whole dried egg powder produced the shortest development time and highest pupation and adult emergence rates, which is valuable information when rearing en masse. The research determined that between 0.5-1.0g/larvae of media is sufficient to produce fully sized adults.
A fifth field trial was completed where flies were released into large enclosures (fine netting) around approximately 30 Hass avocado trees. Two different fly species were (C. vicina and C. dubia) at two different densities (4 treatments) of 200 flies/tree or 400 flies/tree. The fruitlets formed due to pollination by the flies will be assessed in early February 2023.
Project partner SeedPurity Pty Ltd secured additional funding from the Tasmanian Government (Agricultural Development Fund) to support the final stages of developing a mass rearing system for the hover fly E. tenax, which has been shown over the past few years of work by SeedPurity to be a very effective pollinator of seed crops (carrot and brassica). Important production parameters and measures of lifespan, fecundity, developmental rates, and developmental substrates have already been determined to produce up to two million adult flies. The project is at an advanced stage of field deployment and dispersal studies for E. tenax in Tasmanian vegetable seed crops
Glasshouse pollination of strawberries finally got going after long delays in being able to access work sites at Western Sydney University to complete this research. A tagging process was trialled to trace movement of individual flies as they foraged between flowers. Despite some mortality, the flies that survived were active and were observed foraging on flowers, with E. tenax flies visiting flowers more often than blowflies. At the time of completing this report 14th December, 2022), about 25 per cent of fruit had been harvested and measured. All fruit should be harvested and measured by the end of January 2023, with a plan to repeat this experiment in 2023 to ensure informed recommendations for growers.