Dozens of bee species in decline in addition to bumblebees, study suggests

Bees known as sweat bees have been discovered under a Taiwanese woman's eyelid. (Picture: PA Wire/PA Images)

Honey and bumble bees are just two of many species of the insect declining in number, new research suggests.

A study shows the number of more than a dozen wild bee species critical to pollinating everything from blueberries to apples in New England are decreasing.

Researchers from the University of New Hampshire had set out to understand if the documented declines hitting honeybees and bumblebees were also taking a toll on the lesser studied bee species in the US state of New Hampshire.

They examined 119 species from a museum collection at the college dating back 125 years.

Writing in the peer-reviewed journal Insect and Conservation Diversity, Sandra Rehan and Minna Mathiasson concluded 14 species found across New England were on the decline by as much as 90 percent.

Several of them are leafcutter and mining bees.

Bee numbers have been in decline (AFP/Getty Images)

These species, unlike honeybees, nest in the ground.

"We know that wild bees are greatly at risk and not doing well worldwide," Ms Rehan, the senior author on the study, said in a statement.

"This status assessment of wild bees shines a light on the exact species in decline, beside the well-documented bumble bees. Because these species are major players in crop pollination, it raises concerns about compromising the production of key crops and the food supply in general."

Bees have been on the decline for more than a decade across the globe.

Scientists blame a range of factors including insecticides called neonicotinoids, parasites, disease, climate change and lack of a diverse food supply.

Bees are critical pollinators with food making up about a third of the human diet from plants that are pollinated by insects.

Jeff Lozier, a bee expert from the University of Alabama who did not take part in the research, called the study "interesting”, branding the findings a critical step in expanding research into lesser known species.

However, he cautioned that researchers only studied bees in New Hampshire and depended upon bees that were not collected "for the purpose of large scale population surveys."

"The most important use of the data in my view is in providing a baseline set of hypotheses for groups of species that are potentially declining or stable across a much greater set of species than is usually examined, which can then be investigated in more detail to determine why they may be changing," he said.

"This study doesn't really determine the why quite yet, but gives us a reference point for further study."