By connecting the dots between theory and real-life effect, two new studies offer more proof that neonicotinoid insecticides are causing extensive damage to honeybee colonies.
Research studies have linked neonicotinoid insecticides to damage to honeybee colonies, while agricultural and chemical companies claim otherwise. Recent research from teams of Canadian and European researchers, published in the journal Science, deliver sound, real-life evidence that underscores the danger of even sub-lethal doses of these poisons to honeybees, one of the world's essential pollinators.
Insecticides are chemicals intended to kill troublesome pests on food and other crops. While sometimes insect damage to fruits and vegetables is cosmetic, in other cases, insects destroy crops, impacting the food supply and the wage of those who farm for a living.
In the 1990's, neonicotinoid insecticides (NNIs) came into widespread use. These highly effective insecticides work on the nervous system of insects and others exposed to the toxins. In insects, neonicotinoids paralyze and kill their targets.
For humans, the danger of neonictoinoids is not only in the disruption of our food chain, but in exposure to these chemicals through inhalation, contact, and residues in and on our foods. For humans, exposure and bioaccumulation of insecticides in our bodies can lead to cancer, reproductive, endocrine, respiratory, and other severe problems.
These pesticides infiltrate the food supply, water, cooked food, and animal feed. Before you start feeling safe, peeling or washing vegetables or fruit does not gets rid of all of the pesticides. Studies show that these pesticides commonly show up in the human body and breastmilk. We are what we eat — and what we put into our environment.
Earlier studies have shown that exposure to neonicotinoids reduces the diversity and abundance of helpful gut bacteria in bees. NNIs reduce the homing ability of bees and damage their reproductive ability. The damage leaves bees more susceptible to climate and heat stress, and infection. Other practices, like jacking up pollen patties with antibiotics as bee food also damages the ability of honeybees to go about their business creating food for us.
Two studies, one from York University, in Canada, and the other from the Centre For Ecology and Hydrology, in the UK, approached the issue by evaluating neonicotinoid impacts on bees in field studies.
These studies did not overlap. The York University study analyzed the activity of 55 honeybee colonies randomly located in Ontario and Quebec, Canada. The researchers split the hives between locations that were exposed, and unexposed, to neonicotinoid insecticides. The colonies were in place throughout the entire growing season, before planting, until autumn after harvest.
Researchers put hives in the "exposed" group near corn fields. You may not realize it, but almost all corn grows from seeds treated with NNI before planting. So — the pesticide is delivered directly to the seed, the growing plant, and the soil. Many bees die just from the pesticide-laden dust kicked up during the planting process. On the seeds, Canadian researchers "detected 26 different agrochemicals that included miticides, fungicides, herbicides, NNIs, and other insecticides." That said, coating seeds with agricultural chemicals and pesticides avoids toxic windborne drift from aerosolized pesticide applications.
In addition to analyzing pollen, plant, residue, and bee samples, the study authors attached radio frequency identification (RFID) backpacks to bees to monitor their life and death. Findings include:
- The lifespan of worker bees is reduced by almost a quarter (23%) following seasonal exposure to NNIs. Contaminated worker bees live about three weeks, while unexposed bees live about four weeks. Given the intense responsibilities of worker bees, the loss of individuals and productivity is devastating to colonies.
- NNIs are water soluble, and spillover of the pesticide in irrigation and rainwater allows plants in the surrounding area to take up the pesticide, poisoning bees that feed on them. The contaminated pollen that killed and sickened these bees was from contaminated plants in surrounding acres.
- It may seem evident that NNIs during seed planting were dangerous to the bees, but the study found that "honeybee colonies near corn were exposed to NNIs for up to four months," which represents most of the bee season in North America.
- The toxic impact of NNIs on bees is higher when farmers use a common fungicide in the mix of chemicals applied to fields.
In a press release, researcher Amro Zyed, of York University, notes: "This debate about field realistic exposure has been going on for a long time. We needed season-long monitoring of [NNIs] in bee colonies to determine the typical exposure scenarios that occur in the field, which we have now done."
The other study — research done by the Centre for Ecology & Hydrology — was one of the first large-scale "field-realistic" studies to show the impact of NNIs on three different bee species. They studied 33 field sites in Hungary, the United Kingdom, and Germany, growing winter-sown oilseed rape, a crop used for canola oil.
Observing fields grown using seeds treated with a combination of chemicals and pesticides, scientists studied the impact of the pesticide on wild bumble bees (Bombus Terrestris), solitary bees (Osmia bicornis), and standard colonies of honey bees (Apis mellifera).
Of particular interest to the team was "overwinter fitness," the ability of the colony to survive in the year following exposure to sub-lethal doses of NNIs. By measuring colony weight gain, queen, worker, and drone output, along with reproductive cells, researchers evaluated the vulnerability of these three species over time.
The team surveyed the bee colonies throughout the growing season in each country, between April 2015 and March 2016. Researchers collected and analyzed residue gathered from pollen and nectar on the bees and their colonies.
This large-scale geographic research determined the following:
- In Hungary, the number of colonies fell by 24% the year following exposure to NNIs, and survival rate in the UK was "generally very low."
- Harmful effects of NNIs were not found in overwintering honeybees in Germany. Study authors speculate the abundance and availability of alternative flower resources for bees could be a factor.
- In each country, the bumble bees, and solitary bees, saw lower reproductive returns related to NNI residues in the following year.
The study authors remark:
Taken together, our results suggest that exposure to neonicotinoid seed treatments can have negative effects on the interannual reproductive potential of both wild and managed bees, but that these effects are not consistent across countries.
In March, the EU began deliberating banning NNIs entirely. The EU banned specific NNIs on particular food crops in 2013. No similar ban has yet been enacted in the US, although action on the state level may see bans adopted in 2018.
As with climate change, the use of NNIs proceeds at the expense of the health of pollinators, humans, and other organisms. Pesticide poisoning appears to be another inconvenient and troublesome truth. The real question is whether regulatory agencies in a position to act will do so in time.