Study: Pesticides Are Creating Pollination Problems and Killing Bees

Bees Decline

Story at-a-glance -

  • Neonicotinoid pesticides, which are widely used in intensive agricultural operations, have been implicated in the decline of bees, particularly in commercially bred species like honeybees and bumblebees
  • New research has now shown these chemicals are leading to long-term population changes in wild bees as well
  • Wild foraging bees were three times more likely to be negatively affected by exposure to neonicotinoids than non-crop foragers
  • Overall, about 50 percent of the total decline in wild bees was linked to the pesticides

By Dr. Mercola

Neonicotinoid pesticides, which are widely used in intensive agricultural operations, have been implicated in the decline of bees, particularly in commercially bred species like honeybees and bumblebees.

New research published in Nature Communications has now shown these chemicals are leading to long-term population changes in wild bees as well.1

The study involved 18 years of U.K. wild bee distribution data for 62 species, which were compared to amounts of neonicotinoid use in oilseed rape, a crop grown to produce canola oil. The researchers found evidence of increased wild bee population extinction rates in response to neonicotinoid seed treatment.

While bees that forage on oilseed rape have historically benefited from its availability, according to the researchers, once the crops are treated with neonicotinoids (as up to 85 percent of England’s oilseed rape crops are) they have detrimental impacts on the bees.

In fact, wild foraging bees were three times more likely to be negatively affected by exposure to neonicotinoids than non-crop foragers. Overall, about 50 percent of the total decline in wild bees was linked to the pesticides.2

It’s being described as the “first good evidence” that the widespread use of neonicotinoids is harming wild bees at the population level.3 The authors explained:4

“Our results suggest that sub-lethal effects of neonicotinoids could scale up to cause losses of bee biodiversity. Restrictions on neonicotinoid use may reduce population declines.”

Butterfly Declines Also Linked to Neonicotinoids

The evidence continues to build that the use of neonicotinoids could be putting the future of pollinators in jeopardy. In addition to honeybees, bumblebees and wild bees, the chemicals have been implicated in declines of butterflies in Northern California.

Researchers from the University of Nevada tracked 67 butterfly species at four locations for at least 20 years.5 At each site, declines in the number of butterfly species were most closely linked to increased used of neonicotinoids, even more so than other potential factors in butterfly declines, like land development.6

Past studies have shown similarly alarming trends in relation to neonicotinoid usage. In England, for instance, butterfly species declined by 58 percent on farmed land between 2000 and 2009.7

Further, a study in the journal PeerJ found 15 of 17 butterfly species showed negative associations with neonicotinoids. According to the researchers:8

“The declines in butterflies have largely occurred in England, where neonicotinoid usage is at its highest. In Scotland, where neonicotinoid usage is comparatively low, butterfly numbers are stable.”

How Do Neonicotionids Harm Bees?

The majority of soybean, corn, canola and sunflower seeds planted in the U.S. are coated with neonicotinoid pesticides. The chemicals, which are produced by Bayer and Syngenta, travel systemically through the plants and kill insects that munch on their roots and leaves.

When treated with neonicotinoids, all parts of the plant become potentially toxic to insects. Neonicotinoids are powerful neurotoxins and are quite effective at killing the pests, but they’re also harmful to non-target pests, namely pollinators such as bees and butterflies.

This occurs because the pesticides are taken up through the plant's vascular system as it grows and, as a result, the chemical is expressed in the pollen and nectar of the plant.

The effects of different neonicotinoids were long regarded as interchangeable, but one study showed each may affect bees differently. Bayer’s imidacloprid was found to cut the number of egg-containing brood cells by 46 percent.

Syngenta’s thiamethoxam, on the other hand, decreased the number of live bees by 38 percent.

Clothianidin, another neonicotinoid made by Bayer, had the curious effect of increasing the number of queens produced, which the researchers noted could potentially backfire if, “say, all those queens turned out to be infertile.”9,10

Lead researcher Dr. Christopher Connolly of the University of Dundee told The Guardian, “I think there is sufficient evidence for a ban on imidacloprid and thiamethoxam … ”11

Yet, even in response to the U.K. study showing neonicotinoids are linked to declines in wild bee populations, Bayer is making excuses.

One representative for Bayer Crop Science in the U.K. said it’s more likely that intensive agriculture, and not the use of neonicotinoids, per se, is causing issues with pollinators (even though the two go hand-in-hand).12

Fortunately, the European Union (EU) put a temporary ban on the use of neonicotinoids, beginning December 1, 2013 (and still in force today), to study their involvement with bee declines.

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Bees Are Exposed to More Than 30 Pesticides in Pollen

Neonicotinoids represent only one type of pesticides that the average bee may come across while foraging. Other research published in the journal Nature Communications revealed that pollen collected next to cornfields is contaminated with up to 32 different pesticides.13

The highest levels of contamination in pollen came from pyrethroid insecticides, which are often used as repellents for mosquitoes and other household pests.

Both phenothrin, used to repel ticks and fleas, and prallethrin, used primarily for targeting wasps and hornets, were detected in the pollen, as was the common mosquito repellent DEET (N,N-diethyl-meta-toluamide).

The study is in line with a 2013 study, in which researchers analyzed pollen from bee hives in seven major crops and found 35 different pesticides along with high fungicide loads.14 Each sample contained, on average, nine different pesticides and fungicides.

When the pollen was fed to healthy bees, they had a significant decline in the ability to resist infection with the Nosema ceranae parasite, which has been implicated in bee deaths. In all likelihood, it’s not one or two chemicals that are the problem, but many.

Despite this, researchers typically study the effects of only one chemical at a time. What happens with exposure to chemical cocktails, which is a more realistic snapshot of what bees are actually facing, is a mystery.

Even ‘Bee-Friendly’ Plants May Contain Bee-Killing Pesticides

A new report released by Friends of the Earth, an international network of environmental organizations, and Pesticide Research Institute (PRI) revealed that some “bee-friendly” plants sold at major retailers like Home Depot, Lowe’s, Ace Hardware, True Value and Walmart still contain neonicotinoid pesticides that may harm bees.

Looking on the bright side, the chemicals were found in far fewer garden-store plants than they were just a few years ago. The report found a significant decrease in neonicotinoid-containing plants sold by major retailers, from 51 percent in 2014 to 23 percent in 2016.15 According to Friends of the Earth:16

This reduction is likely due to changes in store policies that commit major retailers, including Home Depot and Lowe’s, to eliminate neonicotinoid use on garden plants.

Retailer commitments are having a ripple effect in production methods by suppliers and have resulted in reduced use of neonicotinoids in common garden plants overall.”

Not only is this a win for pollinators, but it also makes good business sense. A poll commissioned by Friends of the Earth and global consumer watchdog group SumofUs revealed that 67 percent of Americans feel more positively about Home Depot and 66 percent feel more positively about Lowe’s because they have formally committed to eliminate neonicotinoid pesticide usage in their plants.

Further, 39 percent said they would feel more negatively about a retailer that did not do so.17 Some retailers are still lagging behind in taking steps to remove these toxic pesticides from their plants.

Further, neonicotinoids are also commonly used in flowering tree production, representing another route of exposure for urban pollinators since such trees are often used along city streets and in business campuses. Report author Susan Kegley, Ph.D., from the Pesticide Research Institute explained that there’s still much work to be done:18

“Our data indicates that compared to two years ago, fewer nurseries and garden stores are selling plants pre-treated with systemic neonicotinoid insecticides … Yet it’s still not possible for a gardener to be sure that the plants they select at the store will be safe for bees and other pollinators. Retailers should work with their suppliers to speed up their phase out of bee-harming pesticides.”

Tell Bayer to Stop Producing Neonicotinoids

It’s extremely important that steps are taken to protect bees, butterflies and other pollinators. These creatures are necessary to help 80 percent of flowering plants reproduce and are involved in the production of one out of every three bites of food. A sampling of the produce that would disappear without bees is below. Imagine a world without it.19











Summer squash




Green onions



Bok choy



Broccoli rabe

Mustard greens

One way you can take action is by joining Friends of the Earth’s campaign to tell Bayer, the leading manufacturer of neonicotinoids, to stop producing these toxic chemicals. As they stated:20

We need bees to pollinate [two-thirds] of the food crops we eat every day — healthy fruits and vegetables matter far more than Bayer's extra profits! So now we need to show Bayer’s CEO that his toxic chemicals are tarnishing the Bayer brand and harming its business.”

How to Create a Bee-Friendly Garden

To avoid harming bees and other helpful pollinators that visit your garden, swap out toxic pesticide and lawn chemicals for organic weed and pest control alternatives. Even some organic formulations can be harmful to beneficial insects, so be sure to vet your products carefully.

Better yet, get rid of your lawn altogether and plant an edible organic garden. Both flower and vegetable gardens provide good honeybee habitats. It's also recommended to keep a small basin of fresh water in your garden or backyard, as bees actually do get thirsty.

In addition, you'll want to grow your own pollinator-friendly plants from organic, untreated seeds. If you opt to purchase starter plants, make sure to ask whether or not they've been pre-treated with pesticides.

Keep in mind that you also help protect the welfare of all pollinators every time you shop organic and grass-fed, as you are actually “voting” for less pesticides and herbicides with every organic and pastured food and consumer product you buy. The video above, from PRI, gives examples of 12 pollinator-friendly plants that are good sources of nectar and pollen to add to your garden.