A project undertaken at the School of Natural Resource Sciences, Queensland University of Technology, and the Australian School of Environmental Studies, Griffith University, and jointly supervised by Anthony Clarke and Jacinta Zalucki
Introduction
Tropical fruit flies (Diptera: Tephritidae) are regarded as the primary horticultural pests of the Pacific region. While we know much about fruit flies as pests, substantially less is known about fruit flies in their native rainforest habitats. Within rainforests, fruit flies are thought to pollinate selected orchid species. Flies are attracted to the orchids through the orchid’s production of fragrance chemicals, which the flies are thought to use in their mating systems. This project will elucidate the functional interactions which occur between fruit fly pollinated orchids and fruit flies in Australia. We will focus research on the Australian native orchid, Bulbophyllum baileyi and Bactrocera species which visit it.
Figure 1. Tropical fruit flies (Bactrocera tryoni) on a Bulbophyllum baileyi blossom
Figure 2. Tropical fruit fly carrying orchid pollen (the paired bright yellow masses) on its thorax
Background & Aims
That fruit flies may pollinate orchid species has been known by orchid workers since the 1960s, but it is only since the 1990s that entomologists have become involved in this field. Work has been prompted by an interest in examining the role of the fragrance chemicals produced by orchids, which in some instances are the same as those used in fruit fly management. Orchids provide a natural source of chemicals to investigate fruit fly chemoecology in the field. Of interest to us is that, in North Queensland, we have observed fruit flies which are known to respond to different lure types all coming to B. baileyi blossoms. This strongly suggests that new fruit fly lures may be developed through intensive study of orchid /fly interactions.
We will:
- use standard pollination biology criteria to formally test that fruit flies do pollinate orchids in the field;
- in Queensland identify the full range of fruit fly species which respond to orchids;
- test the ability of five fruit fly species to individually pollinate B. baileyi; and
- identify in detail, throughout the four day blooming period of an orchid, the link between fly behaviour and the chemical profile of orchid fragrance.
Outcomes
Aims 1 & 2: Quantification of fruit fly visitors and field pollination.
Outcome: Increased fundamental understanding of the evolutionary and ecological interactions between fruit flies and orchids. Orchids and fruit flies are speciose and ecologically important components of Australian rainforests and knowledge of how they interact is of importance for sustainable management.
Aim 3: Difference in pollinator efficiency.
Outcome: Comparitive studies of the ability of different fruit fly species to pollinate a single orchid have not been done. Outcomes (ranked pollination performance across fly species) will significantly enhance our understanding of the evolution of this system.
Aim 4: Analysis of orchid odour profiles and related fly behaviours.
Outcome: The first quantified analysis of fruit fly behaviour with respect to the changing chemical profile of orchid fragrance over time. By identifying the most biologically active compounds within the orchid fragrance, we will be strategically placed to identify novel chemicals for future fruit fly management.
Project team
The project team consists of Dr Tony Clarke (QUT)), an insect ecologist with expertise in fruit flies, and Dr Jacinta Zalucki (GU), a plant pollination ecologist.