Quantcast

New Studies Confirm Pesticide Exposure Major Contributor to Declining Honey Bee Populations

Beyond Pesticides

Researchers at the U.S. Department of Agriculture (USDA) and University of Maryland have found that low levels of pesticide exposure from crop pollination make honey bees more susceptible to the deadly gut parasite Nosema ceranae, contributing to declines in bee populations.

The study’s findings, released July 24 in the journal PLoSONE, expand on a recent report released by the USDA that found parasites, disease, genetics, poor nutrition and pesticide exposure as synergistic factors in the observable nationwide honey bee decline, but focused on technological stopgap measures without questioning the sustainability of widespread systemic neonicotinoid pesticide use. Adding urgency to USDA’s research, another study released July 22 in the Proceedings from the National Academy of Sciences shows that pollinator losses can have a detrimental effects on plant reproduction.

Pesticide Exposure and Susceptibility to Disease

The newest USDA research adds to the growing body of evidence that shows pesticide exposure weakens honey bees’ immune system making them more susceptible to parasites and pathogens. Researchers took pollen samples from crops that honey bees are known to pollinate including apples, watermelons, pumpkins, cucumbers, blueberries and cranberries to determine exposure levels and Nosema infection.

In sum, researchers found 35 different pesticides in pollen, with samples containing, on average, nine different pesticides ranging  in classes from oxadiazines, neonicotinoids, carbamates, cyclodienes, formamidines, organophosphates and pyrethroids. Of these, the report links eight pesticides as increasing the risk of Nosema gut parasite infestations. Researchers most frequently found fungicides in pollen samples, particularly chlorothanlonil, which is a broad spectrum fungicide ubiquitously used on apples and other crops. The presence of fungicides is of particular concern. Not only do fungicides increase risks of infection with deadly Nosema parasites, but they also generally do not carry warning labels to tell farmers to refrain from application while crops are blossoming and bees are foraging, that is, when bees are most susceptible to pesticide poisoning.

Lead researcher Jeff Pettis, PhD at the Bee Research Laboratory in Beltsville, MD explained that honey bees that were fed pollen containing the fungicide chlorothalonil and collected at the hive entrance were almost three times more likely to become infected when exposed to the parasite Nosema, compared with control bees, which were not fed contaminated pollen.

The study shows that honey bees cannot sustain regular exposure to the vast array of agricultural chemical combinations that weaken honey bee immune systems and make them more susceptible to Nosema infestation. The majority of studies up to this point have examined honey bee exposure to only one chemical at a time.

Surprisingly, researchers also found that pesticides were evident in every single pollen sample, even those that were collected from nearby wildflowers that were not sprayed. Co-author Dennis vanEngelsdorp, PhD at the University of Maryland explained “It could be drift from when they sprayed their crop, but it also could be that the bees are picking it up and contaminating the pollen on the forage trip.” Whatever the cause, he continued, we “need to better understand how pesticides are getting into the hive. Clearly it is not just from collecting pollen from the crops that bees are being used to pollinate.”

Pollinator Loss and Impacts on Plant Populations

Adding to the growing body of research on pollinator declines, another study published last week shows that the decline of a single pollinator species significantly impairs plant reproduction. The study, Single pollinator species losses reduce floral fidelity and plant reproductive function, was published in the Proceedings of the National Academy of Sciences, out of the Rocky Mountain Biological Laboratory in Crested Butte, CO.

Researchers examined 20 plots of meadow in the region, removing the most populous bumblebee species out of each plot, and patrolling them regularly to determine whether other pollinator species could fill the shortage for wildflower pollination. Instead, researchers found that in the absence of bumblebees, pollinator species foraged more widely, becoming less devoted to one flower species. Researchers specifically focused on the purple larkspur wildflower, and found that with broader foraging patterns, larkspurs were less likely to receive pollen from the same species, which is required for successful pollination. Because of changes to pollinator assemblages, larkspurs then produced 30 percent fewer seeds. These results demonstrate the wider consequences that loss of pollinators to pesticides can have on plant reproduction as well as ecosystem health.

Background

Since 2006, honey bees nationwide have suffered ongoing and rapid population declines, from hive abandonment and bee die-off in a phenomenon known as colony collapse disorder (CCD). The causes are numerous, however, recent scientific evidence points to the role of a systemic class of pesticides, neonicotinoids, which contaminate pollen, nectar and the wider environment, causing lethal exposure to honey bees and threatening our food systems. An extensive overview of the major studies showing the effects of neonicotinoids on pollinator health can be found on Beyond Pesticides’ What the Science Shows.

In response to massive pollinator declines, recent legislation proposed by Reps. John Conyers (D-MI) and Earl Blumenauer (D-OR), H.R. 2692, The Save America’s Pollinators Act, has called upon the U.S. Environmental Protection Agency to suspend the use of neonicotinoids and to conduct a full review of scientific research before allowing the entry of other neonicotinoids into the market. Tell your Representative to Save America’s Pollinators.

Visit EcoWatch’s BIODIVERSITY page for more related news on this topic.

——–

EcoWatch Daily Newsletter

Natural Resources Defense Council

By Emily Deanne

Shower shoes? Check. Extra-long sheets? Yep. Energy efficiency checklist? No worries — we've got you covered there. If you're one of the nation's 12.1 million full-time undergraduate college students, you no doubt have a lot to keep in mind as you head off to school. If you're reading this, climate change is probably one of them, and with one-third of students choosing to live on campus, dorm life can have a big impact on the health of our planet. In fact, the annual energy use of one typical dormitory room can generate as much greenhouse gas pollution as the tailpipe emissions of a car driven more than 156,000 miles.

Read More Show Less
Kokia drynarioides, commonly known as Hawaiian tree cotton, is a critically endangered species of flowering plant that is endemic to the Big Island of Hawaii. David Eickhoff / Wikipedia

By Lorraine Chow

Kokia drynarioides is a small but significant flowering tree endemic to Hawaii's dry forests. Native Hawaiians used its large, scarlet flowers to make lei. Its sap was used as dye for ropes and nets. Its bark was used medicinally to treat thrush.

Read More Show Less
Sponsored
Frederick Bass / Getty Images

States that invest heavily in renewable energy will generate billions of dollars in health benefits in the next decade instead of spending billions to take care of people getting sick from air pollution caused by burning fossil fuels, according to a new study from MIT and reported on by The Verge.

Read More Show Less
Aerial view of lava flows from the eruption of volcano Kilauea on Hawaii, May 2018. Frizi / iStock / Getty Images

Hawaii's Kilauea volcano could be gearing up for an eruption after a pond of water was discovered inside its summit crater for the first time in recorded history, according to the AP.

Read More Show Less
A couple works in their organic garden. kupicoo / E+ / Getty Images

By Kristin Ohlson

From where I stand inside the South Dakota cornfield I was visiting with entomologist and former USDA scientist Jonathan Lundgren, all the human-inflicted traumas to Earth seem far away. It isn't just that the corn is as high as an elephant's eye — are people singing that song again? — but that the field burgeons and buzzes and chirps with all sorts of other life, too.

Read More Show Less
Sponsored
A competitor in action during the Drambuie World Ice Golf Championships in Uummannaq, Greenland on April 9, 2001. Michael Steele / Allsport / Getty Images

Greenland is open for business, but it's not for sale, Greenland's foreign minister Ane Lone Bagger told Reuters after hearing that President Donald Trump asked his advisers about the feasibility of buying the world's largest island.

Read More Show Less
AFP / Getty Images / S. Platt

Humanity faced its hottest month in at least 140 years in July, the US National Oceanic and Atmospheric Administration (NOAA) said on Thursday. The finding confirms similar analysis provided by its EU counterparts.

Read More Show Less
Newly established oil palm plantation in Central Kalimantan, Indonesia. Rhett A. Butler / Mongabay

By Hans Nicholas Jong

Indonesia's president has made permanent a temporary moratorium on forest-clearing permits for plantations and logging.

It's a policy the government says has proven effective in curtailing deforestation, but whose apparent gains have been criticized by environmental activists as mere "propaganda."

Read More Show Less