To many people, honey bees symbolize
prosperity, sustainability and environmentalism. But as a honey bee researcher,
I have to tell you that only the first item on that list is defensible.
Although they are important for agriculture, honey bees also destabilize
natural ecosystems by competing with native bees—some of which are species at
risk.
The rise in hobby beekeeping, now a
trendy activity for hundreds of thousands of Americans, followed strong
awareness campaigns to “save the bees.” But as a species, honey bees are least
in need of saving. Media attention disproportionately covers them over native
pollinators, and murky messaging has led many citizens—myself once included—to
believe they are doing a good thing for the environment by putting on a
beekeeper’s veil. Unfortunately, they are probably doing more harm than good.
“Beekeeping is for people; it's not a
conservation practice,” says Sheila Colla, an assistant professor and
conservation biologist at Toronto’s York University, Canada. “People mistakenly
think keeping honey bees, or helping honey bees, is somehow helping the native
bees, which are at risk of extinction."
Colla recently published an analysis of
nearly a thousand comments submitted by citizens in response to Ontario’s draft
Pollinator Health Action Plan—a proposal that involved a plan for stricter
neonicotinoid pesticide regulations. Despite intense public interest in bees
and pollination and strong support of tighter pesticide regulations, Colla and
her colleagues found that citizens had a surprisingly poor understanding of the
diversity of pollinators and their roles in pollination.
“The focus on neonics [a kind of
pesticide] and honey bees has taken a ton of resources away from conserving
wild pollinators from their most important threats,” Colla says. She is
justifiably frustrated at the misappropriated attention on saving honey bees
when, from a conservationist’s point of view, native bees are the ones in more
dire need of support.
And while honey bee–centric businesses
often support initiatives that benefit native bees, such as developing
bee-friendly habitat, the financial contributions pale in comparison to what
could be achieved if funds were applied to these initiatives directly.
“Beekeeping companies and various non-science-based initiatives have
financially benefitted from the decline of native pollinators,” Colla explains.
“These resources thus were not allocated to the actual issue people are
concerned about.”
For some reason, maybe because they are
small, honey bees are not generally viewed as the massively distributed
livestock animal that they are. There are millions of honey bee colonies in
North America, 2.8 million of which are in the U.S. Approximating around 30,000
bees per colony (the size of a pollination unit), that’s roughly a billion
honey bees in Canada and the U.S. alone—almost triple the number of people.
High densities of honey bee colonies
increase competition between native pollinators for forage, putting even more
pressure on the wild species that are already in decline. Honey bees are
extreme generalist foragers and monopolize floral resources, thus leading to
exploitative competition—that is, where one species uses up a resource, not
leaving enough to go around.
But determining honey bees' influence on
natural ecosystems requires empirical testing. It is possible, for example,
that alternate foraging habits of native bees—differences in their active times
of day or preferred plants, for example—could lead to little effective
competition. Honey bees are so ubiquitous, though, that it has been hard to
test exactly how their introduction, and subsequent resource monopolization,
affects ecosystem networks.
Not so for the Canary Islands. Alfredo
Valido and Pedro Jordano, researchers from the Spanish National Research
Council in Tenerife and Sevilla, respectively, saw an opportunity to use these
islands—a Spanish archipelago off the northwestern coast of Africa—to study how
the introduction of honey bees affects the native pollinating community.
In the highlands of the islands’ Teide
National Park, thousands of honey bee colonies are introduced seasonally for
honey production and removed again at the end of the nectar flow, creating an
excellent scenario for experimentation. Their results, published in Scientific
Reports, do not make honey bees look like the sustainability celebrities they
have become.
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Bringing in honey bees reduced the
connectedness of the plant-pollinator networks. Nestedness and modularity, two
indicators of ecosystem resilience, also declined. While some plant species
enjoyed higher fruit set, fruits sampled nearest the apiaries contained only
aborted seeds. “The impact of the beehives is so dramatic,” says Valido, “You
can detect disruption between plants and pollinators just the day after beehive
installation.”
“By introducing tens or hundreds of
beehives, the relative density of honey bees increases exponentially compared
with wild native pollinators,” Valido explains. This causes a drastic reduction
of flower resources—pollen and nectar—within the foraging range. “Beekeeping
appears to have more pervasive, negative impacts on biodiversity than it was
previously assumed,” says Jordano.
Valido and Jordano suspect that their
findings on the Canary Islands are generally applicable to other ecosystems
where honey bees are introduced, but they note that the specific impact of
beekeeping in other locations may differ.
Indeed, honey bees are not always the top
competitor in a pollinator network: Whether they succeed at outcompeting the
native bees depends on other factors. For example, Nicholas Balfour and his
colleagues at the University of Sussex, England, found that native bumble bees
were superior competitors on the tubular flowers of lavender, owing in part to
their longer proboscis (tongue).
In still other ecosystems, honey bees
appear not to be as influential as in the Canary Islands. After introduction in
northern Patagonia, nonnative bumble bees and honey bees overtook the native
bees as the most frequent floral visitors, but this had no effect on the native
bees’ actual visitation rates.
While every ecosystem has its own
quirks—with different pollinator players and participating plants—pollination
network studies conducted closer to home tend to agree with the findings in the
Canary Islands. “There have been studies in North America showing pollination
system disruptions by honey bees,” says Colla. “Honey bees also are very
effective at pollinating certain weedy species, which changes the overall plant
communities.”
Many of those weedy species are also
invasive, including Scotch broom, dandelions, Himalayan blackberry and Japanese
knotweed, among others. And beekeepers secretly love invasive plants. Their
intense proliferation provides a lucrative and predictable nectar flow—perfect
for the honey bees, and beekeepers, to capitalize on—but the plants, too,
disrupt native ecosystems.
Even with this boost of forage, there is
sometimes still not enough to go around amongst honey bees, let alone native
bees. In the lower mainland surrounding Vancouver, Canada, I kept a small
research apiary with 15–20 hives. It was my first year keeping research
colonies in a high-density area, and I have never struggled so much to keep my
bees alive.
The hives were riddled with diseases. I
even euthanized one colony with symptoms of American foulbrood—standard
protocol, as it’s one of the most destructive, contagious diseases that honey
bees face. Despite being entirely free of Varroa destructor—a devastating
parasitic mite—at the start of the season, the hives required miticide
treatments by late summer. And the colonies did not produce a crop of honey.
Colony densities in some locations have
become too high, facilitating the spread of disease and exacerbating problems
with poor nutrition. If it was this hard to keep my honey bees healthy, I’m not
sure I can bear to think about the wild bees.
But think about them, we must. I used to
believe that honey bees were a gateway species, and that concern over their
health and prosperity would spill over onto native bees, benefitting them, too.
While this may have happened in some cases, evidence is mounting that misguided
enthusiasm for honey bees has likely been to the native bees’ detriment.
Beekeeping doesn’t make me feel good, anymore. In fact, quite the opposite.
https://www.scientificamerican.com
