Insect Pollinators Face Interlocking Threats

The global decline of honey bees and other pollinating insects is caused by multiple, largely human-induced effects, according to a new study.

Over the past decade, scientists have been reporting steady and mysterious declines in the populations of so-called pollinator insects.

These include the honeybees, wasps, flies, beetles, butterflies and moths that help pollinate three-quarters of the world’s food crops, services worth $200 billion annually to the global economy.

The new report is the first to pull together years of research on pollinator species decline. Forty scientists from six countries worked on the project organized by the Insect Pollinators Initiative of the United Kingdom (IPI).

While no single factor is responsible for the population decline, the analysis finds intensive land use, climate change and the spread of alien species and disease, are among the major threats to pollinating insects.


"What we are beginning to see is that it’s likely that there’s a combination of these effects that are driving the declines in these insects and in some cases they may be combining in subtle ways that exacerbate the overall negative effect,” said Adam Vanbergen, an ecologist with the Britain-based Centre for Ecology and Hydrology who served as the science coordinator on the IPI-led review.

Vanbergen says more research must be done on this complex interplay, across a vast scale, from genetics to worldwide ecosystems.

“We need to launch a whole suite of studies looking at subtle interactions between, say, land use change and its impacts on the resources that insects rely on, and how that can effect interactions with disease organisms or with exposure to pesticides that would be one example,” he said.

The ecologist says there is also a need to carefully document how climate change affects the insects’ ability to adapt to a warmer world.

“There is evidence now accumulating that impacts from these different pressures hits insects at different levels of biological organization," Vanbergen said. "So you have some pressures that will be damaging, for example, the brain function of individual insects and you have other pressures that will be perhaps affecting the ability of species to move in landscapes or indeed their range across continents.”

Learning how to protect pollinators from these environmental pressures will require a multi-disciplinary scientific effort. Farmers, policy makers, and industry will need to collaborate on programs to conserve these species.

“We need to come together really to try and set the appropriate framework to enable strategic planning at a landscape scale," said Vanbergen. "That’s going to be important if we are going to devise the appropriate habitat network to help support these insects in order to buffer them against effects such as climate change and local effects such as pesticide impacts.”

The IPI analysis also calls for re-evaluating common pesticide risks and developing new treatments for insect disease.

“All we really need to do is just try to build a more sympathetic approach to integrate practices that are able to lessen some of these impacts and to support the biodiversity that provides these important ecosystem services to human kind,” said Vanbergen.