Massachusetts bees threatened by pesticides, parasites and climate

Bees collecting pollen outside the Christian Science Center. Photo Courtesy: Emily Hughes

By Lindsey Vickers
BU News Service

BOSTON – Massachusetts beekeepers reported losing more than half of their colonies in the 2015-2016 season, raising concerns for the health and safety of a pollinator central to farming and food production. Worries for the insects’ well-being have sparked discussions around the world about everything from pesticides to backyard plants that support native bees.

The rate of honeybee colony loss in Massachusetts puts the state in the top 10% of states, according to the Massachusetts Pollinator Protection Plan.

Legislation such as H. 763, filed by state Rep. Carolyn Dykema, D-Holliston, aims to protect pollinators by decreasing neonicotinoid use by “further regulating the spraying, release deposit or application of a neonicotinoid.”

The bill would also limit access to neonics, permitting only certified or licensed applicators to apply the pesticide.

Research has shown that neonics are most likely to be overused or over-applied by nonprofessionals, according Nathalie Steinhauer, who received her doctoral degree from the University of Maryland as part of the Honeybee Epidemiology Lab. Restricting usage to professionals, and working to ensure the correct dosage and methods are understood and followed, would likely help bees.

Bee decline has been a topic of international concern since the early 2000s, when colony collapse disorder was first observed. The disorder, which is still not well understood, is likely a result of multiple factors, including colony transportation, habitat changes and stress. Now, bees face challenges with pesticides, climate change and parasites taking tolls on both native and European honeybees worldwide.

As much as 45% of Massachusetts agricultural crops rely on pollinators, according to Kim Skyrm, the chief apiary inspector and apiary program coordinator at the state Department of Agricultural Resources.

Though agriculture is a fairly small industry in Massachusetts, the state is a primary producer of certain crops specific to the East Coast, such as cranberries, according to the National Association of State Departments of Agriculture.

Massachusetts is the second largest cranberry producer in the nation. From 2015 to 2017, the annual cranberry yield was more than one million 100-pound barrels, according to data from the U.S. Department of Agriculture. Sales of the fruit brought nearly $50 million into the state’s economy in 2018, according to the USDA.

But cranberries, as well as apples and other agricultural products, are highly dependent on bees for pollination, making declining populations and colony losses concerning. Bees are the main pollinators of cranberries, according to a report by researchers at Rutgers.

News has largely focused on pollination by honeybees when considering crop productivity and related economic concerns. But native bee species, which play an integral role in pollination, are often overlooked. Both native bees and honeybees are central to pollination in Massachusetts and elsewhere.

Native bees significantly contribute to pollinating agricultural crops, but some are also specialized to certain types of wildflowers.

In terms of agriculture, “studies (of) apples, blueberries, and other fruits and vegetables have shown that honeybees do less than half of the crop pollination, particularly in the Northeast,” Dr. Kimberly Stoner, an agricultural scientist in the Entomology Department of the Connecticut Agricultural Experiment Station, wrote in an email.

Moreover, researchers have already observed a “dramatic decline [in the population of] 14 wild bee species that are, among other things, important across the Northeast for the pollination of major local crops such as apples, blueberries, and cranberries.”

Ultimately, both native bee species and the European honeybee face significant environmental and human-generated challenges, from pesticide use to climate change, and even parasites that transmit viruses.


One type of pesticide that has been in the spotlight recently is neonicotinoids, or neonics, which were banned by the European Union in 2018 because of negative effects on pollinators. Even at sub-lethal levels, the pesticide has significant effects, including disrupting bee communication and cognitive abilities, according to a report published by the Xerces Society for Invertebrate Conservation.

Neonics work by targeting an insect’s nicotine receptors, which are located in the bug’s central nervous system.

This pesticide class is “among the recommended materials for a wide range of insect pests” across Massachusetts, according to Sonia Schloemann, an expert on agriculture and fruit production at the University of Massachusetts-Amherst.

Neonics are a systemic pesticide, meaning that once treated, seeds and young plants will permanently carry traces of the product. The chemicals persist, and are present in treated plants’ pollen and nectar, according to a summary of the report. Plants can even indirectly absorb neonics through the “residue of some of the neonicotinoids that persisted in the soil from the previous year.”

Bees come into contact with the pesticide through the plant’s pollen and nectar. This is more troublesome for some species than others.

“There is considerable evidence that native bees are more strongly affected by pesticides. All bees, of course, are susceptible to most insecticides if exposed to high enough concentrations. Honeybees seem to be protected by the large size of their colonies, while other bees are more heavily exposed to the environment,” Stoner wrote.

The consequences of contact for native bees, especially bumblebees, which are two to three times more sensitive to neonics’ toxicity than honeybees, are serious. According to Stoner’s research, even at low levels, imidacloprid, a specific type of neonicotinoid, significantly impacts bumblebees, causing them to become less efficient at foraging and even changing their reproductive behaviors, she found.

Although Dykema’s legislation may lead to an overall improvement, many of the pesticides that affect bees in Massachusetts are being used in suburban backyards to control mosquitoes, moths, and other bugs.

Tony Lulek, a beekeeper from Holliston who has been working with honeybees since 2004, wrote in an email that given the smaller scale of agriculture and farming taking place in Massachusetts, neonic regulations are likely to have less of an effect on individual beekeepers.


Varroa mites are the most significant problem facing bee colonies in Massachusetts, according to Hannah Whitehead, the honeybee extension educator at UMass-Amherst.

The mites are an invasive species native to Asia. There, the mite is a parasite of the Asian or Eastern honeybee. However, Asian honeybees co-evolved with the mite, allowing them to develop various defense mechanisms and survive with the parasite. Worker bees of this species, for example, practice “varroa sensitive hygiene,” through which they detect and remove varroa mites from eggs and developing pupae, according to researchers.

European honeybees, the domestic bee species present in the United States, in contrast, are frequently killed by the mites, which first appeared in the U.S. in the late 1980s. Since then they have spread across the country. The mites are even present in Hawaii, as of 2007.

“If you were to imagine something the size of a football sitting on your shoulder … that’s kind of what a mite is like [to a bee] … [they] feed off fat in the bee,” said Kathy Halamka from Unity Farm in Sherborn.

This decreases the bee’s overall health, potentially making it more susceptible to pesticides or other environmental problems.

In addition, the mites transmit viruses, according to professors from the Department of Entomology at the University of Tennessee, Knoxville.

Untreated mites, in temperate climates, are likely to kill off colonies within three to four years by out-reproducing the bees.

In a 2017-2018 season survey of 49 Massachusetts beekeepers, conducted by the Massachusetts Department of Agricultural Resources, 9% reported that varroa mites were the reason for colony deaths.

Meanwhile, 24% of colony deaths were attrivuted to environmental factors, such as drought and heat.

Climate change is proving to be another challenge for bees, for a variety of reasons ranging from subtle shifts in overall climate and temperature, causing bees to miss pollination windows, to increasing frequencies of droughts and high temperatures.

Though bees face mounting threats, they are essential pollinators for agricultural crops and wild ecosystem alike. They are responsible for one in three bites of food we have in Massachusetts, Dykema said.

This article was originally published in the Worcester Telegram and MetroWest Daily News.

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