When a Cornell-led team of scientists analyzed two dozen environmental factors to understand bumblebee population declines and range contractions, they expected to find stressors like changes in land use, geography or insecticides.
Instead, they found a shocker: fungicides, commonly thought to have no impact.
“Insecticides work; they kill insects. Fungicides have been largely overlooked because they are not targeted for insects, but fungicides may not be quite as benign – toward bumblebees – as we once thought. This surprised us,” said Scott McArt, assistant professor of entomology and the lead author on a new study published Nov. 15 in the journal Proceedings of the Royal Society B.
While science has studied insecticides, such as neonicotinoids, that attack bugs’ central nervous systems, this new work shows how fungicides – particularly chlorothalonil, a general-use fungicide often found in bumblebee and honeybee hives – may negatively affect bee health, said McArt, a fellow at Cornell’s Atkinson Center for a Sustainable Future.
Building on a large data set collected by Sydney Cameron, professor of entomology at the University of Illinois, the scientists discovered what they call “landscape-scale” connections between fungicide usage, pathogen prevalence and declines of endangered United States bumblebees. (Landscape scale refers to the area in which foraging bumblebees live, about 2 kilometers in diameter.)
While fungicides control plant pathogens in crops, the bees pick up their residue when foraging for pollen and nectar. As farms use both insecticides and fungicides, the scientists worry about synergy. “While most fungicides are relatively nontoxic to bees, many are known to interact synergistically with insecticides, greatly increasing their toxicity to the bees,” McArt said.
Chlorothalonil has been linked to stunted colony growth in bumblebees and an increased vulnerability to Nosema, a fatal gut infection in bumblebees and honeybees.
“Nosema can be devastating to bumblebees and honeybees,” said McArt. “Since fungicide exposure can increase susceptibility of bees to Nosema, this may be the reason we’re seeing links between fungicide exposure, Nosema prevalence and bumblebee declines across the United States in this data set.”
For domestic and global agriculture, bumblebees are a key component due to their ability to use “buzz pollination” that vibrates and shakes pollen loose from flowers. In the United States, bees contribute more than $15 billion to the economy and $170 billion to global agribusiness, according to global economic research and a 2012 Cornell study. While half of crop pollination work is done by commercially managed honeybees in the U.S., the other half is done by bumblebees and wild bees. In New York, pollination services contribute $500 million to the state’s agricultural economy.
McArt and his Cornell colleagues will continue to investigate fungicide-insecticide synergisms and fungicide-pathogen interactions under the New York State Pollinator Protection Plan and a new grant from the New York Farm Viability Institute.
The Latest on: Bee decline
Buzzworthy: Dickinson College using grant to save bees
on July 11, 2018 at 6:47 pm
"They provided us funding to help understand the causes of pollinator decline and some things that we can do to reverse those declines," said Douglas. The study involves studying bees and other pollin... […]
Lawmakers to study declining monarch butterfly and bee populations
on July 11, 2018 at 6:45 pm
AUSTIN (KXAN) — The population of monarch butterflies continues to decline and are down about 15 percent from a year ago, according to numbers from a Texas A&M University monarch butterfly researcher. ... […]
Costco asks suppliers to drop neonicotinoids in effort to save bees
on July 11, 2018 at 3:32 pm
Echoing Denotter's comment on the unclear cause of death for some of the bees, the chair of the Ontario Fruit and Vegetable Growers' Association crop protection section says it's habitat loss that is ... […]
These Aerial Drones Are Supporting Farmers When Bees Are in Short Supply
on July 11, 2018 at 10:20 am
Governments, businesses, and individuals are all scrambling to nourish dwindling bee populations. Since such a large percentage of the world’s food supply is grown with the help of honeybees, their de... […]
Bee farmer in Peterborough makes offer to land owners
on July 11, 2018 at 3:59 am
A bee farmer is offering land owners free, organic bee friendly flower seeds as part of his campaign to halt the decline of the British honeybee. Jez Rose, owner of Bees for Business, based at Langtof... […]
How Bee Saving Paper May Give Bumbling Insects a Fighting Chance
on July 10, 2018 at 7:05 am
We know our innovation won’t solve the worldwide problem of the declining bee population by itself, but we hope we’ll at least make people realize how important bees are to us.” The Bee Saving Paper i... […]
CU Boulder instructor introduces parking lot plots for bees: 'The bees can't wait'
on July 9, 2018 at 5:22 pm
Honeybee and native bee populations are plummeting, according to the City of Boulder, and their decline places the "entire natural system in peril." The plot Bilot and her students installed acts like ... […]
Ivy Academy program raising bees in face of population decline
on June 29, 2018 at 9:03 pm
Ivy Academy student Noah Lewis walks outside to inspect the school's bee population each week. Curious students eagerly watch from a distance as the senior beekeeper inspects the hive, looking for sig... […]
The Plight of the Humble Bee
on June 29, 2018 at 12:45 pm
The world’s bees are in decline, driving up the price of pollination so high it has spurred a black market of bee rustlers dealing in stolen hives. The almond growers of California’s central valley, w... […]
Climate Change Linked to Bee Decline
on June 28, 2018 at 1:32 pm
A new study from Northwestern University and the Chicago Botanic Garden has found that climate change may drive local extinction of mason bees in Arizona and other naturally warm climates. A new study ... […]
via Google News and Bing News