following my previous post, here is a letter to Science Magazine, regarding a previous article on pollinator decline
Qualifying pollinator decline evidence
THE POLLINATION CRISIS has garnered perhaps more public interest than any other environmental problem short of climate change. It is therefore remarkable that it is based on such limited science. D. Goulson et al. acknowledge that evidence for pollinator declines is almost entirely confined to honey bees and bumblebees in Europe and North America. Yet they conclude that "it is probably reasonable to assume that declines are also occurring elsewhere across the globe."
This is a possibility, but not one that can be well justified by current evidence. Their statement extrapolates data from north temperate bumblebees (a single and rather unrepresentative clade), which include less than 0.6% of the 20,000 worldwide bee species. The data are also derived from among the most intensively farmed landscapes in the world. Concern about future food insecurity due to pollinator losses rests on this shaky foundation, despite, as yet, any sign of declining crop production.
Goulson et al. also bemoan minimal uptake of pollinator-promoting incentives on farmland. They attribute this to insufficient understanding among farmers of the economic benefits of pollinators. I expect, however, that farmers are more familiar with the economics of farming than ecologists. Although pollinators might elevate crop production, this has to be set in the context of other farm management interventions.
It is difficult to envisage a more pollinator-dependent crop than Californian almonds, which Goulson et al. suggest are threatened by continuing honey bee decline. Yet, the 60-year decline of honey bees has been paralleled by increasing almond production and associated profits. The most productive years have been the past five (2010 to 2014) when honey bee colonies have been at their lowest since records began in 1947.
We should make every effort to harness the public interest in pollinators to emphasize the value of, and need for, conservation. In doing so, we should not, however, blind ourselves to the limitations of our own data.
Jaboury Ghazoul
Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland.
SCIENCE, 29 MAY 2015 • VOL 348 ISSUE 6238 981
[Note: of course, records began long before 1947, but people frequently start from there because that was the high point, reached as result of incentives to beekeeping during WWII. Records from the early part of the twentieth century indicate that honey bee colonies in the US probably numbered between 2 to 4 million]
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