Many farmers don’t spray insecticides any more — but insecticides are still used on nearly all food crops in Canada.

Neonicotinoids — members of a relatively new class of insecticides — are applied to crop seeds before planting. After planting, these insecticides spread into every plant cell, and into plant nectar and pollen. The entire plant becomes toxic.

Any insect coming into contact with the plant — a leaf-eating or sap-sucking pest, or a nectar-seeking pollinator — may be poisoned.

Chemists synthesized neonicotinoids in the 1980s by attaching chlorine atoms to molecules similar to nicotine. The resulting compounds resist degradation. Neonicotinoids bind to nerve cells and block their normal function. Once bound, they cannot readily be dislodged. They accumulate over time. More and more nerve cells cease to function: inhibiting memory, impacting muscle performance and compromising immune systems.

Regulators have designed toxicity tests on the premise that pesticides are sprayed on plants and kill insects on contact. These tests indicate that short-term neonicotinoid exposure is less harmful to non-target animals, including humans, than exposure to conventional pesticides. But test results conceal the long-term impacts of neonicotinoids. Animals that tolerate a single high dose die after several weeks of exposure to far lower levels.

Hundreds of scientific studies have documented neonicotinoid toxicity, mainly focused on bees. Successful pollination by bees and other plant pollinators determines crop yield. No farmer wants to kill off animals that provide a free and essential agricultural service. Yet beekeepers find empty hives, surrounded by dead bees, in agricultural landscapes where neonicotinoid use is widespread. Where corn and soybeans cover the agricultural landscape, as in much of Eastern Canada, virtually every planted seed is coated with neonicotinoids.

The chemical industry claims there is no proof that neonicotinoids are the main cause of bee death, and points to other factors such as viral pathogens and mite infestations. These claims are wearing thin. Scientists recently discovered the biochemical mechanism by which a neonicotinoid insecticide shuts down anti-viral defences in honey bees, leaving hives vulnerable to pathogen outbreaks.

Neonicotinoids have certainly proven effective in killing plant pests. They are now the world’s most widely used class of insecticides. Health Canada’s Pest Management Regulatory Agency (PMRA) has registered neonicotinoids for virtually every crop grown in Canada.

Neonicotinoids do not selectively target plant pests, or even insects. Birds that eat treated seeds are also at risk. A review of The Impact of the Nation’s Most Widely Used Insecticides on Birds by the American Bird Conservancy calls for a ban on the use of neonicotinoids as seed treatments.

Neonicotinoids also accumulate in soil. They are toxic to earthworms and other soil organisms. They are water soluble and readily migrate into lakes, creeks and streams where they persist in sediments and poison aquatic life.

A new study “Macro-Invertebrate Decline in Surface Water Polluted with Imidacloprid,” “is the first large-scale research based on multiple years of actual field monitoring data that shows that neonicotinoid insecticide pollution occurring in surface water has a strong negative effect on aquatic invertebrate life, with potentially far-reaching consequences for the food chain and ecosystem functions.” Some scientists fear that widespread death of insects is contributing to current massive declines in insect-feeding groups such as swallows, swifts, bats and frogs.

PMRA is now seeking public comment on its Notice of Intent NOI2013-01, Action to Protect Bees from Exposure to Neonicotinoid Pesticides. According to PMRA, “current agricultural practices related to the use of neonicotinoid treated corn and soybean seed are affecting the environment due to their impacts on bees and other pollinators.” PMRA has proposed measures such as enhanced warnings on pesticide and seed package labels.

The Sierra Club of Canada is campaigning for stronger action. It points out that CropLife Canada, the trade association representing the pesticide industry, is lobbying for continued neonicotinoid use and has hired former Conservative MP and cabinet member Ted Menzies as its new president and CEO. While noting that the Conflict of Interest Act bars Mr. Menzies from lobbying government officials or giving his new employer “information that was obtained in his or her capacity as a public office holder and is not available to the public,” a Sierra Club media release asks “Is CropLife Buying Influence?”

The battle lines are drawn. You have an opportunity to ask PMRA to take action based on scientific evidence and the public interest. The deadline for comments is December 12, 2013.

Ole Hendrickson is a forest ecologist and current president of the Ottawa River Institute, a non-profit charitable organization based in the Ottawa Valley.

Photo: Josh Gallaway/flickr

Ole Hendrickson

Ole Hendrickson

Ole Hendrickson is an ecologist, a former federal research scientist, and chair of the Sierra Club Canada Foundation's national conservation committee.