Yesterday afternoon saw the official launch of POSTnote 348, on ‘Insect Pollination’, written by the 2009 BES POST Fellow Rebecca Ross. The note summarises the causes and consequences of the declines in UK insect pollinators: a subject that has received growing attention in recent years, as demonstrated by the large audience crowding the seminar room in Westminster.

Chaired by John Penrose MP, the seminar began with a presentation from Dr Liz McIntosh of the Food and Environment Research Agency (Fera), promoting BeeBase, the Government initiative to register all beekeepers. The ex-President of the British Beekeepers Association Ivor Davis then spoke, pointing at the lack of professional teaching available to beekeepers for the decline in the number of honey bees in the UK – a view echoed by comments from other beekeepers in the room. Whilst welcoming the Government’s pledge to invest £10.5 million into bee research, he expressed concern that it would all be spent on high level research rather than achieving practical, immediate goals.

Dr Simon Potts of the University of Reading then discussed the consequences of pollinator decline. Pollinator services in the UK are valued at around £440 million, or 13 % of the total value of agriculture. As only 10% of this is provided by domestic honey bees, Dr Potts highlighted the economic sense of protecting wild pollinators, at a fraction of the cost that would be incurred trying to replace them. This was theme continued by Dr Claire Carvel of the Centre for Ecology and Hydrology in her presentation on research into using field margin strips in Countryside Stewardship agri-environment measures to support pollinators. Comments from the floor questioned the practicalities of planting such pollinator friendly margins, for example whether regional eco-types would be considered, and challenged researchers and policy-makers to improve the implementation of these schemes amongst farmers.

Find out more about the BES POST Fellowship: applications for the 2010 scheme will open in February.

On 20 January a joint BES, Parliamentary Office of Science and Technology (POST) seminar will explore the causes and consequences of declines in insect pollinators. The event will see the formal launch of POSTnote 348 on ‘Insect Pollination’, authored by the 2009 BES POST Fellow, Rebecca Ross.

Pollination is the transfer of pollen from one flower to another, enabling plant reproduction. Pollination by insects is therefore vital for the maintenance of biodiversity and agricultural production. 80% of British wildflowers and 84% of EU crops depend on insect pollinators, mainly bees. Loss of pollinators would cost UK agriculture an estimated £400m per annum, representing 12% of agricultural revenue. Evidence is mounting that British bee species, such as honeybees and bumblebees, are in decline, which could threaten future agricultural productivity and cause further biodiversity loss. What is causing this decline, and is further action needed to restore our pollinators?

We will hear from expert speakers on the scientific and practical aspects of maintaining a healthy pollinator population and there will be a chance to discuss such topics as:

• Does pollinator decline pose a significant threat to the UK?
• What research do we need to understand pollinator decline and mitigate
its effects?
• What can we do to improve the health of managed honeybees?
• What policies do we need to maintain wild pollinators in the landscape
despite increasing demands on land for housing, fuel and food?

For further information and details on how to register for a place at this event, see the ‘Forthcoming Policy Meetings’ section of the BES website.

The stereotypical image of the hard-working bumblebee has been shattered by new research published in the journal Behavioural Ecology and Social Biology.

Scientists from Queen Mary University London have found that bumblebees Bombus terrestris will only work if they absolutely have to – an evolved strategy to conserve energy in times of plenty.

Bees are known to respond to cues describing how full their food reserves are; successful foragers will reduce the number of runs to and from a nectar source, and fewer bees will engage in foraging trips. Molet and Raine, the lead authors of this study, investigated whether bees will respond to a third cue, that of recruitment pheromones.

To investigate this idea, the team attached minute radio transmitters (Radio Frequency Identification or RFIDs) to the bees, to determine the frequency of visits to pollen sites within the study area. The researchers created a concoction of chemicals that closely resembled bumblebees’ natural cue pheromone, and also used a single chemical cue, to examine recruitment response. The bouts were recorded in 30 minute intervals, and during each interval the researchers monitored how ‘full’ the honeypots were.

Although pheromones increased the number of foraging bouts and new recruits, the bees were far less likely to respond when food reserves were well stocked, effectively ignoring the invitation to forage for nectar.

Dr Raine described how the chemical cue given off by single foragers to collect more food was not always heeded:

“If there isn’t stuff to collect, a lot of them are pretty much on standby. They will be sitting around doing very little, or apparently so.”

In summary, the research shows that bees use a suite of complex cues, (recruitment pheromone, frequency of visits by other foraging bees, and food reserve fullness) to decide whether or not to bother going out and foraging for food. This is the first time bumblebees’ response to pheromones has been shown to be tempered by another cue, in this case – colony nutrition status.

The research has potential implications for commercial crop pollination. A healthy, well fed colony may be more reluctant to go out looking or food – and thus pollinating – if the incentive isn’t there. In the study the bumblebees were up to four times more responsive to the natural, 3-chemical pheromone mix than the single eucalyptus cue, therefore using the right chemical make-up when enticing bees is essential to motivating them.

However the bees reputation has not been completely tarnished. Dr Raine said that its not that the bumblebees are lazy, they have simply evolved an effective strategy to conserve energy when food is plentiful, and they are busy when there is work to be done.

Reference: Molet, M., Chittka, L., Stelzer, R.J., Streit, S., & Raine, N.E., 2008, Colony nutritional status modulates worker responses to foraging recruitment pheromone in the bumblebee Bombus terrestris, Behavioural Ecology and Sociobiology, 62:1919–1926, DOI 10.1007/s00265-008-0623-3

Recent research published in the British Ecological Society’s Journal of Applied Ecology suggests greater attention ought to be paid to seed predators, especially in the context of natural and agro-ecosystems.

Considerable research efforts have suggested that there is, or could be a link between insect pollinator decline and agricultural output. The body of science on the subject of pollinators and agriculture has influenced policy at the highest level; the creation of the International Initiative for the Conservation and Sustainable Use of Pollinators (IPI) at a United Nations meeting in 2000.

However, new research published in Current Biology suggests that agriculture has not been affected by the decline of key insect pollinators.

Examining a period spanning over 40 years, Alexandra Klein’s research time investigated agricultural productivity of crops requiring pollinators with those that do not. Contrary to popular belief, the researchers found that crop yields have gone up consistently, with growth rates of up to 1.5%, despite the falling numbers of pollinators. Focusing on tropical agricultural regions, no difference in yields were found between breeze and insect pollinated crops, (though it is not known whether these regions had experienced significant concurrent pollinator declines).

It is possible that the researchers, having grouped together all crops globally, might not be picking up on detail happening at finer spatial scales.

The results of this work are out of sync with the work of many others such as Taylor Ricketts, director of WWF’s conservation science programme. Rickett’s group found that coffee plantations were 20 per cent more productive when grown within 1km of forested areas. Other work has also suggested that an abundant diversity of pollinators increases crop yields.

Some scientists remain sceptical. Jaboury Ghazoul, a plant ecologist at ETH Zurich, Switzerland, believes that few crop species actually depend on pollinator species.

Klein however does not rescind the notion that pollinators are very important for agriculture. She suggests that actions by farmers at the local level, (such as hand pollination or pollinator transplantation) may mask the extent of pollinator decline. Klein anticipates that a crop productivity crash could occur any time soon – many major crop plants now are pollinator dependent, 15% up from 8% in 1961.

Do blog readers think that agricultural productivity can continue with a concurrent decline in pollinators? Is there an optimum spatial scale to conduct this kind of research? Is pollinator diversity important?

Source: Aizen M. A., Garibaldi, L. A., Cunningham, S. A. & Klein, A. M., 2008, Current Biology, doi:10.1016/j.cub.2008.08.066