The Possible Introduction of Bumblebees for Pollination of Horticulture Crops in Australia

 

Proceedings from the Workshop held
25-26 November 1999 in Hobart

 

About the workshop

Thirty-four industry, government, and conservationist stakeholders participated in the National Bumblebee Workshop which was facilitated by Dr Peter Box (Integra Ltd), hosted by the Tasmanian Museum & Art Gallery (TMAG) and made financially possible by Horticultural Research Development Corporation (HRDC) Project No. VG99033. The Hydroponic Farmers Federation (HFF) provided additional funding.

The Issues

	Identification of the key environmental questions relating to the possible introduction of bumblebees to Australia.
	Evaluation and confirmation of the research methodology necessary to address the key environmental issues for a HRDC funded project.

Before arrival, participants were provided with all background information including the submission to Australian Quarantine Inspection Service (AQIS) and Environment Australia (EA) regarding the introduction of bumblebees to Australia. On day one of the workshop, participants were told that:

• they were not charged with deciding whether or not bumblebees should be allowed into mainland Australia (EA's role), but rather to make sure the right questions are addressed in the project,
• there are obviously a lot of associated issues (commercial issues, use of native bees, etc) but these were not the focus of the workshop (however there was time on day two to discuss concerns), and
• there is a steering committee to finalise the methodology for the project.

Afterwards, eight key representatives from government, conservationist, beekeeping, horticulture and environment sectors gave a series of short talks, presenting their views on the possible introduction of bumblebees to Australia. Presentations covered a variety of points from quarantine procedures to bumblebee colony development. In general, speakers were asked to:

• take the perspective of the stakeholder group; not just a personal stance,
• provide an overview of their concerns,
• provide the reasons and/or evidence to support their view, and
• identify which environmental issues or other questions (from their point of view) need to be researched as a basis for EA to make a decision.

In the afternoon, based on all of the presentations, seven table groups (each led by a member of the Steering Committee) discussed and identified five key environmental issues that specifically need to be researched. (See pages 3-7.) The whole group then reviewed these points, and descriptions of the main issues (and the reasons for them) were listed in order of importance. Day one finished with a summary of relevant references, parallel research projects and the proposed methodology for this project (including data collected since October 1999) for consideration at this Workshop.

Day two was a half-day session. First, working in table groups, further detail, refinements and improvements to the issues and/or methodology of the project thus far were proposed to the whole group. Then, table groups identified three of the most critical issues or questions, outside the brief of the present project, that require investigation, e.g. using other bees or insects for pollination, or genetically modifying the crops themselves to self-pollinate. A secondary aim here was to farm out these projects to individuals or agencies able to deal with them.

 

 

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Outcomes: Working Groups identify the key questions to address in an EIS, and suggest methodologies

 

1. Distribution

The following questions were identified as important:

• What is the current distribution of B. terrestris in Tasmania?
• What is the potential distribution?
• Can B. terrestris maintain successful colonies in native vegetation?
• Why is B. terrestris not yet in Launceston (but is near Devonport)?
• How far into the native vegetation does B. terrestris produce successful colonies?
• What are the effects of landscape structure & geographical region on the importance of competition?

 

Methodology suggested by group to investigate these issues*:

• Public Survey, using a postcard size survey form, with simple, brief questions (e.g. where and when?) and relevant lifelike insect images to aid with identification, to be distributed to the following agencies:
  1. Parks & Wildlife
  2. Fire Brigade (Rural)
  3. CSIRO Double Helix Club
  4. Landcare
  5. Beekeepers
  6. Weed Alert Network
  7. Field Naturalists
  8. Bushwalkers
  9. Garden clubs
  10. Internet

   Further suggestions to enhance the survey and estimate future distribution:

  1. Use CLIMEX and survey data to predict distribution.
  2. Map red clover (or other suitable species) over State for forage observation: August to April , targetting particular areas to survey.
  3. Collect pollen samples from bumblebees and use to determine food plant species.

   

• Survival trials (to test possible habitat distribution)

  Place colonies in key areas and determine whether they will successfully establish (minimum of five colonies in ten sites). Environmental and legal risks, ethics and approval of relevant authorities must be evaluated first. Non-sensitive areas may be suitable for transplantation.

• Use indicator plants to determine presence or absence of B. terrestris. Observations to be made over three years, during each flowering season, targeting the following areas of the State that have unusual meteorological and/or geographical characteristics:

  Dry East Coast

  Wet NNW

  Launceston (bumblebees appear to have bypassed the city, for unknown reasons)

   

2. Pests and pathogens

Issues to be addressed:

• Are there any pests and/or pathogens associated with B. terrestris in Tasmania (either native or introduced)?
• What are the pests and /or pathogens associated with B. terrestris that can impact on native bees or honeybees?

 

Methodology suggested by group*:

• Monitor 20 colonies a year, noting only presence or absence of pests and commensals.
• Screen for Melittobia wasp infestation. At three-week intervals, inspect five cocoons in each bumblebee nest, noting any entrance holes or adult wasps.
• Screen for nematodes in November (50 queens) Hobart area.
• Observe for predators.

*Since virus pathology is beyond the resources of this project, it was recommended to seek another agency, e.g. RIRDC, within the honeybee research section, to fund and conduct such research.

 

3. Effect on other species of pollinators

Issues to be addressed:

• What impacts does B. terrestris have on native fauna (birds, bees or other insects)?
• Does B. terrestris have an impact on the reproductive success of native birds, native bees, or other insects?
• What factors affect the size of native bee colonies?*
• Is food availability the only limiting factor governing the size of native bee colonies?*
• Does bumblebee foraging activity affect food availability for native bees/birds, etc?

 

Methodology suggested by group**:

• Choose ten sites: five control sites, where Exoneura/native bees are present, and five sites where both B. terrestris and Exoneura are present. Sites should be away from urban areas, and numbers of Exoneura nests between paired sites must be standardized.
• Measure before and after effect on the breeding success of native bees over a two year period, where in Year One, breeding success (colony survival and brood production) at all sites is measured, and then bumblebees are introduced (two colonies per site) at five sites in Year Two.
• Monitor pollinator/bee numbers fortnightly.

* Later rejected by workshop peers as being beyond the scope of this project.

**Later criticism by workshop peer: How does this mimic natural B. terrestris populations? Concern was raised regarding the use of just one native species. Exoneura may be more resilient than some native pollinators. Therefore it was suggested to also monitor all pollinators present in the area, and observe relative scarcity, rather than just measure reproductive success at the end. The group noted that it is possible to concurrently monitor and observe: 

1. Exoneura,
2. Relative abundance of other bees, and
3. Resource availability, by estimating numbers of flowers, nectar and pollen size. (This should be recorded to assess whether bumblebees are significantly depleting food resources.)

 

4. Impact on Native Plants

Issues:

• Which native plants does B. terrestris impact on, and what are those impacts?
• Does B. terrestris alter seed set and gene flow of native plant populations?
• Will pollination by B. terrestris favour some native plant species over others (e.g. if they enhance pollination of some species will this change composition of native ecosystems)?
• Which plants being visited by B. terrestris are most likely to be impacted (positively or negatively)?
• Which plants are visited by B. terrestris?
• Which plants do native bees visit?

 

Methodology suggested by group:

Firstly a Null Hypothesis is required. The Null Hypothesis proposed by the group was:

In matched sites seed set in select native plant species is the same in B. terrestris occupied versus free areas.

 

• Thirty sites are required, separated spatially; 2m x 2m square quadrats, with enough flowers of the selected species in each. Select sites where all impacts can be observed. Investigate seed set over two or three years.
• Plant species from two different groups are required: three species from plants with flower parts requiring pollination by specialists (e.g. native pea), and three species of plants with flower parts normally pollinated by generalists (e.g. eucalypts).
• Reproductive biology for controls must be understood. Bear in mind that with selective abortion by plants, other factors may be involved. Plants that self-pollinate need to be identified beforehand; flower-bagging experiments to exclude pollinators may be required. Note that there is no need to be concerned about each kind of flower visitor.
• Estimates of plant age are required. A sub-sample of a whole plant should be represented as seeds per pod, per stem, per plant. Determine what background information needs to be collected at each site and/or each visit, e.g. climatic conditions.
• Proceed to analysis: assume that seed set equals fertility.

5. Sleeping Weeds

Issues. The following questions need to be addressed:

• Do bumblebees alter seed set and gene flow of exotic plant populations?
• Which species of weeds do bumblebees have an impact on, and what are those impacts?
• Will bumblebees increase seed set and viability of sleeping (or drowsy) weeds? (To answer this question, it will be necessary to seek advice from weed experts, and may require a more focussed study, such as a University Honours project.)

 

Methodology suggested by group:

• Choose three focal species most likely to be a problem. (Tagasaste may also need to be included as a fourth category):

Cropping weed	Environmental weed	Cropping & Environmental weed
Solanaceous species	Foxglove	Brassicaeae species

• Begin as soon as possible to cover at least two years. Conduct manipulative experiments in greenhouse and observations in the field.
• In a controlled environment, measure effect of Bombus visitation on seed set and viability:
  1. Bumblebees plus honeybees, Apis mellifera
  2. A. mellifera only
  3. Nil
• In the field, select transects of relevant weed species. Choose sites where bumblebees are present, and an equal number of control sites. Replicate treatments.

 

 

Further outcomes: alternative/comparable methods to pollinate greenhouse (tomato) crops: questions and strategies

1. Using carpenter bees, e.g. Lestis auratus

Issues:

• Is it eventually possible for carpenter bees to pollinate commercial greenhouse crops year-round, biologically (managing diapause) and economically (cost competitive with bumblebees)?
• How long would it take to develop such a service?
• Are similar numbers of carpenter bees required for pollination in greenhouses as for bumblebees?
• What would be the environmental impact of distributing carpenter bees around Australia, especially to areas where it is non-endemic (i.e. Tasmania)?
• Given the small size of the Tasmanian greenhouse industry, would it be more environmentally acceptable to commercially rear carpenter bees there instead of B. terrestris?

 

Action suggested by group:

Research conducted by universities and government agencies in this area is proceeding at a relatively slow rate. Funds from HRDC and the horticulture industry are required to speed up the process. 

 

2. Genetically manipulating crops to self-pollinate

Issues:

This is theoretically possible, but is it socially acceptable?

 

Action suggested by group:

Implementation of this option rests with the horticultural industry.

 

3. Using honeybees effectively and economically

Issues

Are there methodologies that allow the practical, economic, year-round use of honeybees in greenhouses?

 

Action suggested by group:

The horticultural and beekeeping industries should jointly look into this possibility.

 

Next steps

• A major consensus of the meeting was that research on weeds would be the most fruitful area to pursue, given the size and budget of the project. Because weeds impact on so much of society, other agencies, such as universities and landcare groups, are expected to contribute to research outcomes.
  
• Tracking the distribution of bumblebees in Tasmania is an important factor in predicting the environmental effect on mainland Australia, along with the accompanying potential spread of disease and parasites. Impact of bumblebees on native plants, sleeping weeds, and other species of pollinators are complex interactions that can and must be studied simultaneously.
  
• Formal notification of alternate strategy recommendations to relevant institutions would be accomplished by circulating these Proceedings.
  
• The Steering Committee met on the afternoon of the second day to further consider key questions, and to detail the methodology necessary to answer them. However before beginning some of the experimental procedures, it would be necessary to consult a biometrician, and the legality of transferring bumblebee colonies within Tasmania for experimental purposes was also still to be resolved.
  
• The Committee stipulated that each of the five major concerns would have an external referee for advice on methodology. They also agreed that on-going communication for all participants and interested parties would be a regular feature of this project, via e-mail and the Internet.
  
• The Committee strongly recommended that extra funding and agencies (such as university Honours or Ph.D. projects) be recruited to help with the research goals proposed by the Workshop.
  
• It is anticipated that the Steering Committee will meet at least once yearly, to guide the project.