Bees Could Disappear

Bernard Vaissière: "Yes, the Bees Could Disappear"
By Jean-Luc Goudet
Futura-Sciences

Friday 07 September 2007

Bee populations are declining all over the world. That fact has been known for a long time and the press has recently latched onto the subject. Bernard Vaissière, an Inra [French National Institute for Agricultural Research] researcher and one of very few French pollination specialists, evaluates this question for Futura-Sciences.
Bernard Vaissière is responsible for research at Inra [French National Institute for Agricultural Research] Avignon, and is the principal for the Laboratory of Entomophile Pollination.

His team's research concerns the interactions between pollen, its vectors (wind or insect) and the pistil, pollinating effectiveness, and the relationships between bees and landscapes and the impact of pollination on agriculture.

Futura-Sciences: What do we really know about the global decline of bee populations?

Bernard Vaissière: We don't know their numbers exactly. The statistics that have circulated in recent press articles are not correct. First of all, you must know that bees are not the only pollinating insects - although they are the main one - and that among bees, there is not only the domesticated bee, as many believe in France.... There are a thousand species of bees in our country and 20,000 in the world! What is certain is that we have clear evidence showing a reduction in populations. In July 2006, an article published in Science showed the decline of wild bee populations (not counting bumblebees) in the United Kingdom and Holland. At the end of 2006, the results of an American study indicated a comparable decline in the United States.

For domesticated bees, we have also observed in the United States a very strong winter mortality, from 30 to 50 percent of colonies at the end of this winter and the 2005-2006 winter, versus five to 10 percent in a normal situation. In France and in Belgium, that winter mortality had reached the same level in recent years; however, according to the CNDA (Centre national du développement apicole [National Center for Beekeeping Development]), mortality was reduced last winter to eight to 10 percent.

FS: Do we know the causes for this apparent return to normal?

Bernard Vaissière: No. Is it a simple respite, due, for example, to a milder winter? The prohibition on Gaucho and Regent [pesticides] is also a possible cause. But we have no proof of that.

FS: An American team has just published an article in Science that points to the responsibility of a virus for the collapse of domestic bee colonies. Do you think that's possible?

Bernard Vaissière: They're talking about the Israeli Acute Paralysis Virus. The Acute Paralysis Virus was already known, also in France, and it is certainly possible that it is the primary agent responsible. But the causes of the mortality for domesticated bees may be multiple, and it is always difficult to sort out potentially multi-factor phenomena. It is also very likely that their food, pesticides, and the Varroa destructor, an acarid parasite, play a big role. That acarid weakens the bees and makes them more sensitive to other factors, as, for example, viral infection.

FS: Are the bees really in danger?

Bernard Vaissière: Yes. I think that today the likelihood of a significant decline in bee populations, even the complete disappearance of certain species, is real. The domesticated bee is sort of a barometer for wild populations, the numbers of which we have not the means of knowing. In France especially, there are very few researchers working on pollinators and insect pollination. In my team, we are three scientists, including two teacher-researchers. We have not hired anyone new for eighteen years! And specialists in pollinating insects are mostly over 60 years old.... On the other hand, we know that bees are fragile and we know why: they feed almost exclusively on the nectar and pollen that plants produce for them. That's the fruit of a long co-evolution with flowering plants. Herbivorous insects that eat leaves, for example, ingest all kinds of poisons such as alkaloids and tannins and protect themselves with the help of detoxification enzymes. Bees are very poorly endowed with such enzymes.

FS: Pollen is not only transported by insects: there's also the wind ...

Bernard Vaissière: We have studied this question. Apart from insects, flowering plants have two other main pollination modes in Europe: passive self-pollination (pollination takes place within the center of the same flower by way of direct contact between the anthers and stigma or by gravity - which is the case of wheat, for example) and wind pollination. But insect (essentially bee) pollination is involved in 80 percent of flowering plant species. As Jean Louveaux, who was the Inra director at Bures-sur-Yvette, used to say, pollinating insects represent a slight biomass, but they are nonetheless very important: they act as catalysts.

FS: Are crops involved?

Bernard Vaissière: According to an international study covering 115 crops and conducted in 200 countries by teams from France, Germany, the United States and Australia, three-quarters of crops are for the most part pollinated by insects. That's the case for most fruit, vegetable, oil-producing and protein-producing crops, as well as for nuts, spices, coffee and cocoa. Only 25 percent of crops don't depend on pollinating insects at all (mainly cereals, such as wheat, corn and rice). Overall, 35 percent of global food production comes from crops that depend on insect pollination.

FS: Is there significant awareness of this phenomenon?

Bernard Vaissière: In 2004, Europe launched the program, Alarm (Assessing large-scale environmental risks for biodiversity with tested methods) which will terminate in 2008. There have already been advances, such as the article on the parallel decline of wild bees and plants pollinated by bees, which appeared in the July 2006 issue of Science. There are also several leads being explored to reverse the trend, such as, for example, fields set aside to flower, on which work is underway to measure their impact on the maintenance of pollinating populations. But some phytosanitary companies have seized on that lead and the statistics published are sometimes iffy.... The impact is probably beneficial only if one carefully chooses the species planted and their flowering schedule and we still lack the perspective to make precise recommendations on the impact and minimum surfaces necessary.

FS: Does the situation seem reversible to you?

Bernard Vaissière: As long as the species have not disappeared, it does ... although the bees' haplodiploid system does not encourage small populations. And there are positive signs, such as the Alarm program. These actions remain modest, but, like pollinating insects, they could act as a catalyst.