July/August – 2004
Author: Steven Carruthers
The cases for and against the importation of bumblebees onto mainland Australia to pollinate crops
STEVEN CARRUTHERS analyses the cases for and against the application to introduce the bumblebee, B. terrestris, onto mainland Australia for crop pollination purposes. Should importation be allowed, he reports bumblebees will not dramatically change the status of the native and agricultural ecosystems, and there will be significant cost-savings for Australian growers as well as improved yields and fruit quality. He writes there will also be environmental benefits with a large reduction in the use of pesticides, that will also lead to improved worker and food safety.
The Australian Hydroponics & Greenhouse Association (AHGA) has taken the next step in applying to the Department of Environment and Heritage (DEH) to allow the import of bumblebees ( Bombus terrestris) onto mainland Australia to pollinate commercial greenhouse crops. The final three-step process began in April 2004 when the industry’s Draft Terms of Reference were posted on the DEH website for a period of 10 days to allow members of the public the opportunity to comment. The terms of reference outline the areas that interested parties believe should be examined prior to any determination on the application by the Federal Minister.
Step 2 requires the AHGA to write a detailed report that considers the points raised in the terms of reference, which will then be posted on the DEH website for 20 days to allow for further public comments.
Step 3 requires the AHGA to consider the public comments from Step 2, and produce a ‘final report’ for the Federal Minister for the Environment and Heritage. The Minister then consults with other Federal, State and Territory Ministers before deciding whether to add B. terrestris to the list of species suitable for import onto mainland Australia.
Greenhouse growers and other industry members will have their opportunity to have a say during Step 2 of the application process. At the time of going to press, the AHGA was still waiting to receive the public comments from Step 1.
In the meantime, the application to import bumblebees onto mainland Australia has provoked a strong response from conservationists opposed to it.
Bombus terrestris was accidentally introduced into Tasmania in 1992 where, in this most temperate of Australian climates, it has since spread to regions with good rainfall, mostly in urban areas where there is an abundant supply of nectar and pollen from preferred introduced plant species (Hergstrom et al. , 2002). Natural or accidental migration from Tasmania to the mainland cannot be ruled out (interceptions at two ports have been reported recently), but establishment has not so far occurred and is generally considered unlikely given unfavourable climate and lack of continuous food resources.
Broadly, those who oppose the application claim that, if allowed import onto the mainland, B. terrestris will invade a wide range of wilderness areas and compete with native bird and bee species for nectar and pollen, and possibly spread weeds through increasing seed set. Their case is primarily based on the study of bumblebees in Tasmania by Hingston (1999).
The case for the application
Why do Australian growers want bumblebee technology? Bombus terrestris is an effective pollinator of tomatoes because of its ability to extract pollen from the poricidal anthers by vibrating them at an appropriate frequency. Bumblebees are also effective pollinators of other important commercial crops including capsicum, eggplant and strawberry. While honeybees will also pollinate tomatoes, bumblebees are the preferred pollinators in greenhouses because they remain on the crop more than honeybees. Honeybees don’t like the conditions inside the greenhouse and usually escape.
Overseas, bumblebee technology has led to improved Integrated Pest Management (IPM) practices in greenhouses, resulting in adoption of biological control and a large reduction in the use of pesticides and other spray chemicals. These chemicals are not only expensive, but compromise food safety, worker health, and the environment.
In Australia, there have been some limited research trials using native bees to pollinate greenhouse tomatoes. The blue-banded bee (Amegilla spp.) has shown the most promise, but goes into dormancy when the weather cools. Tomato flowers do not produce nectar, so researchers also need to develop artificial feeders. Most greenhouse industry experts agree it will be many years before researchers are able to commercialise artificial hives for greenhouse applications, if at all.
Currently, Australian greenhouse growers pollinate their crops using mechanical, hand-held vibrators, usually three times weekly at a high labour, equipment and maintenance (battery) cost. The AHGA estimates hand pollination will take 780 man hours per year for a 6,00osqm greenhouse growing two crops per year. On a casual rate of $16/hr, the total labour cost is $12,480/year or $2.08sqm. For a single tomato crop grown over a year, mechanical pollination will take 1,040 man hours at a cost of $16,640 or $2.77/sqm. Then there are the costs of vibrators and expensive batteries, and the secondment of trolleys for pollination duties when they can’t be used for other jobs.
By comparison, in Holland, the cost of bumblebee hives is around AU$117, and AU$140 in New Zealand. According to Dutch greenhouse data, a grower of tomatoes needs eight hives per hectare (8 hives/ha), and a grower of cherry tomatoes needs 12 hives/ha. A hive can have a life expectancy of anywhere between six weeks and three months, depending upon conditions. It’s usual to assume an average hive life of two months.
For cherry tomatoes, it will take seven hives to cover a 6,000sqm greenhouse area. The pollination period would be about 10 months (over two crops), so the grower would need 35 hives/year. Even at $160 per hive, this would be a total of $5, 600/year, or $0.93/sqm/year. This is a saving of $6,880/year compared to hand pollination, and $11,040 for one 12-month tomato crop. In both crop scenarios, there is more than a 50% saving to growers compared to mechanical pollination.
“The overseas experience has shown that bumblebee technology also improves yields and fruit quality and this, of course, is at no extra cost,” said Tasmanian greenhouse tomato grower, Mr Marcus Brandsema, who conducted the analysis on behalf of the AHGA.
Increased overseas competition
Overseas competition is also driving the case to import bumblebees onto mainland Australia. In 2002, Biosecurity Australia (BA) approved the import of greenhouse tomatoes from New Zealand. By December 2002, Australia had imported 330, 000kg of tomatoes worth $796,460. In December 2003, NZ tomato imports rose to 354,900kg worth over $1 million, a growth of 25% over the first year of imports, and the figures for 2004 are set to go even higher. In January, Australia imported 256,000kg of Kiwi tomatoes, valued at around $840,000.
There are apparent mitigating factors for this increase in tomato imports. The NZapplication to allow the import of Kiwi tomatoes was approved on the basis of meeting shortfalls in the Australian market as a result of drought in the Bowen and Bundaberg tomato-producing regions. However, in spite of the ongoing drought, Australia has managed to export five varieties of tomatoes worth more than $5 million a year to New Zealand.
Australian tomato growers will come under even more pressure with the arrival of the first Dutch greenhouse-grown tomatoes. In October 2003, Biosecurity Australia finalised the import conditions for truss tomatoes from the Netherlands to Australia. In the near future, Australian consumers will be introduced to high quality, greenhouse-grown Dutch tomatoes, elegantly packaged as tamper-resistant functional foods. If the marketeers follow European trends, then this packaging will include a symbol of the bumblebee, a consumer guarantee that these tomatoes are pesticide-free.
Both Dutch and New Zealand tomato growers use bumblebee technology to improve fruit yields and quality. In fact, Australia is about the only country with a large protected cropping industry that doesn’t use bumblebee technology. It’s to New Zealand’s credit that growers moved to state-of-the-art greenhouse technology several years ago. Today, all Kiwi tomatoes are grown in modern greenhouses, mostly glass, using automated nutrient management and climate control systems, as well as bumblebee technology to lower production costs compared to Australian growers.
The problem here is that the Australian greenhouse industry is underdeveloped compared to Holland and New Zealand, mainly because of a lack of investment in the industry. However, this is changing with significant greenhouse developments either on the drawing board or underway in Victoria, South Australia, and the Bundaberg region of Queensland.
Nonetheless, growers will still be disadvantaged because Australia has no commercial pollinator and no native species of bumblebee. Although researchers are trialing several native bee species as alternatives to bumblebees, this research is still in its infancy. Of those native bees being trialed, Amegilla shows the most promise as a pollinator of tomato crops however, commercial rearing and the development of artificial hives for greenhouse applications are still many years off. Finding a buzz pollinator that effectively pollinates tomatoes is one issue:rearing it in commercial quantities at an acceptable cost is quite a different proposition. A good reality check is to look at the 10 years of research that has gone into finding a natural enemy for control of western flower thrips in Australia. Many candidates ate thrips, but only one, the Queensland-originating predatory mite Typhlodromips montdorensis, lent itself to mass rearing.
The application to import B. terrestris for commercial use in greenhouses was actually first made in 1997. Concerns raised at the time resulted in a three-year Environmental Impact Study (EIS) on the impact of B. terrestris on Tasmania’s flora and fauna. The EIS was funded by Horticulture Australia and the AHGA, and the outcomes were reviewed in Practical Hydroponics & Greenhouses (Issue 69).
The AHGA also funded a climatology study using the CLIMEX model, (Hergstrom, 2003) to predict where B. terrestris is likely to spread should it be allowed importation to mainland Australia, or hitch a ride on strong winds across the Bass Strait.
Both the EIS and CLIMEX studies indicate bumblebees will not dramatically change the status of native and agricultural eco-systems. The CLIMEX study indicates the likelihood of only limited distribution of B. terrestris on mainland Australia should it arrive either by accident or design. The study predicts these areas will be restricted to the wetter areas of Victoria, the south-west corner of Western Australia, and a limited area of NSW across the northeastern border of Victoria, most likely in irrigated areas and urban gardens where there is an abundance of year-round nectar from preferred introduced plant species.
To ensure there are no or limited negative effects of bumblebees establishing in the wild, any importation would be tightly controlled, using ‘clean’ bees. These bees would form the nucleus of the commercial rearing unit. To provide further safeguards, modern commercial bumblebee hives are designed to prevent the escape of queens. It is also possible, but twice as expensive, to design and distribute worker-only nests at the greenhouse site (Griffiths, 2004).
The case against the application
Spearheading the case against the application to import bumblebees onto mainland Australia is the Australian Native Bee Research Centre (ANBRC), which claims bumblebees will invade a wide range of habitats and feed on a wide range of plants with negative impacts on native species. They frequently quote studies by Hingston (1999) as evidence of resource competition. However, industry experts and international scientists say this study is questionable science (see article this issue: ‘A Critical Study’).
The Hingston study on resource competition was conducted over only two days in two small adjacent quadrants, comparing bumblebees foraging with two unidentified native bee species of the Chalicodoma genus (recently renamed the Megachile genus).
However, weaknesses in the methodology make conclusions based on statistical analysis less than reliable. There are also serious omissions in the data on bumblebee activity during the study period.
A good example of the weaknesses in the Hingston experiment was demonstrated when Hergstrom et al. spent hundreds of hours monitoring exactly the same site, and came up with quite a different result.
Those opposed to the application have tried to implicate bumblebees as a potential threat to native bird species that share the same nectar and pollen resources. They particularly point to the endangered Swift Parrot (Lathamus discolor), which breeds only in the blue gum (Eucalyptus globulus) forests of Tasmania. The Swift Parrot migrates to the mainland every autumn to winter, and can be found mostly in the nectar-rich, box-ironbark forests and woodlands of Victoria and New South Wales. Recent sightings across southern Queensland suggest this species is also a regular visitor to that State.
The conservationists claim the Swift Parrot is largely dependent on nectar and pollen from E. globulus, and there is little breeding in the years when flowering of this tree is poor. They claim B. terrestris robs nectar and pollen from this tree, and point to the Hingston study of bumblebees observed on E. globulus over a four-month period as evidence. Two years later, Hergstrom studied B. terrestris over the same seasonal period, at 18 sites, and came to a completely different result. Hergstrom reports bumblebees only represented 2% of potential pollinators of E. globulus. Honeybees were by far the dominant pollinator (56%), followed by birds (25%). Native bees represented 4% of visitors.
In nature, competition for resources is the norm, not the exception. Even though it appears there will be less nectar available in flowers from each visitor, it’s stretching it to make assumptions on the long-term survival of native species utilising the same food resources, based on observations over a short time period and over a small sample area (1ha of suburban bushland). The fact that different species may feed on E. globulus nectar at some time, is not evidence of a negative impact.
The conservationists also fail to mention a key published paper on the Swift Parrot (McNally and Horrocks, 1999), that finds there were no relationships between measures of eucalypt flowering and densities of Swift Parrot in its winter range in central Victoria.
According to Birds Australia, a respected conservation group (www.birdsaustralia.com.au), the decline of the Swift Parrot is attributed to land clearing of more than 85% of their preferred wintering habitats, and continual clearing of 500-1,000 hectares of its breeding habitat for commercial wood-chipping every year. Many individuals also die after colliding with man-made structures, such as windows and tennis court fences.
Conservationists also compare bumblebees with honeybees (Apis mellifera) and their impact on Australian eco-systems, but they fail to mention a key study by Manning (1997), which criticises existing scientific studies relating to the impact of honeybees on Australian wildlife. Despite years of study, there is no consensus on the impact of the ubiquitous honeybee on Australian eco-systems.
Those opposed to the application claim bumblebees have invaded every corner of Israel, including the desert, since their introduction there more than a decade ago. They point to the Dafni (1998) study that predicts bumblebees will colonise the country. However, Israeli and international scientists have refuted the methodologies and predictions of this study.
According to Rivka Offenbach, a vegetable consultant in both greenhouse and open field vegetables in the Arava region, the use of bumblebees is widespread over Israel, including the desert areas, but only in greenhouses. “The bees are in closed structures isolated by nets,” she said. “Although the structures are not absolutely sealed, and some bees get out of the greenhouses, there is no spread of these bees in nature, and they are not able to reproduce. We did not find any damage to other insects in the desert,” she added.
According to Dr Shimon Steinberg, principal entomologist with Bio-Bee Biological Systems in Israel and a world-renowned expert on bumblebees, there is no evidence to support Dafni’s conclusions about widespread establishment of B terrestris in Israel (pers. corresp.).
“There is no evidence of feral establishment of B. terrestris in Israel outside its natural range, ” he said.
Apart from Dafni’s ‘research’ on the infamous single tree outside his office, he also co-authored on an area ravaged by fire. Dr Steinberg says this was just re-invasion of limited natural resources after the fire. Dafni admitted that B. terrestris has declined there over the past two years.
Bio-Bee also export B. terrestris to Japan where it was introduced a few years ago – this is significant because this would presumably be a warm temperature species. Japan has a number of native Bombus species, but attempts to commercially mass produce them failed because they were too expensive. Apart from intial opposition from a flawed study, Dr Steinberg reports he is not aware of any problems with B. terrestris in Japan. This is also supported by reports kept in Japan of feral bees.
These aren’t the only issues conservationists have with the application to import bumblebees onto mainland Australia, but they are the most significant. I don’t want to underplay the significance of these issues, especially as it relates to weed species, but space is a premium and the impact of bumblebees on weed species is dealt with in Dr Griffiths’ Critical Study (page 42).
The use of bumblebees to pollinate greenhouse crops will result in a significant increase in yields and fruit quality, as it has done in Europe, the USA, Japan, Israel and New Zealand. Australia is one of the few developed countries that doesn’t have access to bumblebee technology.
Bumblebee technology has also led to improved Integrated Pest Management practices, resulting in a large reduction in the use of pesticides and other spray chemicals. These chemicals are not only expensive, but can compromise food safety, worker safety and the environment.
There have been limited trials using the blue-banded native bee to buzz pollinate tomato flowers, but it will be many years before researchers are able to commercialise artificial hives for greenhouse applications, if at all, by which time bumblebees may have already migrated to the mainland. There has been an appalling lack of communication between native bee researchers and industry, which only recently became aware of the three-year trial to comercialise artificial hives for greenhouse applications. Nearing the end of its first year, the trial has yet to publish any milestone reports.
A cost:benefit analysis of using bumblebees to pollinate greenhouse tomatoes has found bumblebee technology will reduce pollination costs for a 6,000sqm greenhouse by more than 50%. The saving on pesticides is another significant cost saving for growers, and good news for consumers and the environment.
With the accidental introduction of B. terrestris in Tasmania, the industry funded an EIS and CLIMEX study to determine the likely impacts on Tasmania’s flora and fauna as a yardstick to predict likely outcomes on mainland Australia should it be allowed import, or migrates from the island State. Both the EIS and CLIMEX study indicate that bumblebees will not dramatically change the status of native and agricultural eco-systems on mainland Australia, and its distribution will be limited to the wetter regions of Victoria, southern NSW and south-west Western Australia, mainly in urban gardens.
A further safeguard if B. terrestris is approved for commercial release in Australia, is to only import a clean species sourced from a temperate region. This strain, being adapted to a colder climate, would be less likely to survive the hot summers experienced in most parts of mainland Australia, including all of those areas identified in the CLIMEX study as potentially capable of supporting B. terrestris. However, this wouldn’t be the best option for operating in hot greenhouses.
The case against the application has been based on conjecture and questionable science, using material that only supports that position and ignoring all information to the contrary. For example, opponents fail to mention that there have been several attempts to introduce Bombus species onto mainland Australia, including Victoria in the 1930’s and NSW in 1891 and 1912 (these early introductions from New Zealand were probably temperate species, which is why they didn’t establish on the mainland).
Nonetheless, the conservation lobby has been successful in getting B. terrestris listed as a ‘Key Threatening Process’ in Victoria and New South Wales. However, attempts to list the bumblebee as a Key Threatening Process at a Federal level failed when the Minister for the Environment and Heritage, Dr David Kemp, declined the application on the basis of insufficient evidence.
Under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), a ‘Key Threatening Process’ is defined as any process that threatens or may threaten the survival, abundance or evolutionary development of a native species or ecological community. For example, predation by the European Fox is a key threatening process. One suspects that the spectre of foxes and cane toads must have loomed large in government thinking. I have been unable to find any reliable literature where B. terrestris has been listed as a pest, including those countries where Bombus has been introduced for greenhouse pollination.
There are many cautions in biological literature about drawing inferences from short-term observations like those demonstrated in the Hingston studies. In the scale of time, the ‘Swift Parrot Recovery Plan’, an initiative of Birds Australia, reports there have been only three breeding seasons over a 10-year period (1985-95) when food supplies were abundant. This was based on gum honey production figures. Even the three-year Environmental Impact Study is a short study period to arrive at objective conclusions;but this and the CLIMEX study are the best science we have in which to make predictions about the potential establishment and distribution of B. terrestris on the mainland should it be allowed import, or arrive by accident or design.
As a result of claims made by the conservation lobby, the very real issues concerning the impact of bumblebees in Australia have become clouded by emotive statements designed to galvanise public opposition against the application. This makes it very difficult to conduct serious scientific studies that will provide a solid basis for objective decision-making. Questionable science is also the reason why there is no consensus on the impact of honeybees on the Australian biota – the debate will continue!
Greenhouse growers and industry members have an opportunity to show their support for the application during Stage 2 of the process, when the ‘detailed report’ is posted on the DEH website for 20 days.
In the meantime, the industry can only hope that good science prevails.
About the author
Steven Carruthers is the Managing Editor of Practical Hydroponics & Greenhouses magazine, and Vice-President of the Australian Hydroponic & Greenhouse Association.
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PH&G July-August 2004 / Issue 77