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Neonics & Pollinator Decline

Neonics & Pollinator Decline

How Neonics Spread

Neonicotinoids or “neonics” are a group of insecticides that are chemically related to nicotine. If you’ve bought garden plants from a big box store, or grabbed a few ears of corn from your grocery, you may have encountered them.
In Canada, five of these insecticides are approved for use on many of our foods, including corn, soy, peas, beans, fruits and vegetables. They are applied to the plant as seed coatings, soil solutions, or as sprays on the leaves and stems. They remain active in the plant for many months, and in the soil up to several years.

You can’t wash your hands of it

Neonics are a systemic pesticide. They can’t be washed off of our apples or rinsed from our garden flowers. They are inside the plant, having been taken up by the leaves or roots and distributed throughout by the vascular system. All parts of the plant are affected, including the stem, flowers, fruits, nectar and pollen. When insects ingest fluids or tissues from a treated plant, the neonics damage their central nervous system, causing tremors, paralysis and sometimes death.

Neonics are now the most widely used insecticides in the world with a global market value of billions of dollars annually. However, mounting evidence suggests unforeseen, negative effects on non-target species and the environment.

In our Environment

 

Neonics are highly soluble in water, which is the reason they can travel to all parts of a plant. They also last a long time both in the plant and the soil around it. This combination not only makes them desirable insecticides, but also potent environmental contaminants. Water can easily transport neonics throughout soils and into waterways. Once there, they take months (possibly years) to break down.

Domino effect

Neonics can now be found in some water bodies at levels that are toxic to aquatic insect species like midges and mayflies. This can cause serious disruptions in the food chain. In the Netherlands, declines of insects from neonics have been linked to declines of insect-eating birds. Birds can also be harmed directly if they eat neonic-coated seeds. In a Canadian study, migratory White-crowned Sparrows exposed to a dose of a neonic equal to four to eight treated canola seeds a day over three days lost a quarter of their body weight.

Depending on the concentration and mode of delivery of the neonic, it’s likely that many other species are harmed. Although amphibians and fish are less sensitive to neonics than insects, studies show neonics to be toxic to them at high doses, or after long exposures. Neonics can alter the eating patterns of earthworms to the point that they starve.

A Problem For Pollinators

Without pollinators, where would we be? By some estimates, 30 per cent of our food is made possible by the bees, beetles, flies, birds and butterflies that help grow our food — and let’s not forget honey! Honeybees produce honey from nectar and pollen collected from flowers. But now many pollinators get more than pollen and nectar when they visit blooms in our agricultural fields. In Canada, neonics have been found in the pollen and nectar of many crops.

Hundreds of studies show that the use of neonics causes pollinators like bees significant harm. It affects their ability to navigate, learn, collect food and reproduce. Bumble bee colonies permeated with neonics grow more slowly and produce fewer queens.

Not just agriculture

It’s not just our food we need to worry about. About 75 to 95 per cent of Earth’s flowering plants rely on pollinators for reproduction. But many wild pollinators are put at risk when they fly over the farm fence to feed on the blooms of crops treated with neonics. In some areas, butterflies are sharply declining where their habitat is nearby agricultural areas. Neonics are one more problem for our disappearing wild pollinators to handle on top of habitat loss, disease, climate change and competition or predation from introduced species.

Are Neonics Worth It?

 

We have come to rely on insecticides like neonics for the control of pests on our food crops, garden flowers, tree farms and even the fleas on our dogs. We routinely apply these chemicals even before they are needed as insurance against a pest outbreak that may or may not occur. “It’s like taking antibiotics to avoid getting ill, before you are ill,” says biologist David Goulson, a scientist with the Task Force on Systemic Pesticides.
But is it worth it?

Wasted Effort

This “prophylactic use” of neonics greatly increases the number of non-target species like bees and pest-eating beetles that are killed or exposed to sub-lethal but harmful doses. It means a lot of insecticide needlessly ends up in our environment. By some estimates, 90 per cent of insecticides aren’t taken up by target plants, but instead find their way into our soils, waterways and wild food chains.

Widespread over-use of neonics is accelerating the rate at which insect pests all over the world are developing resistance. For example, just ten years after the neonic imidacloprid was introduced, 95 per cent of Colorado Potato Beetle populations in the Northeastern and Midwestern USA showed resistance. Yet despite increasing rates of pest resistance, many producers still consider neonics to be beneficial.

Neonics ≠ increased yield

Few studies have tested whether neonics are actually beneficial or not. Those studies that have tested the benefits of neonics show their effectiveness to be inconsistent and hard to predict. They often don’t increase yield, and when they do, the effect is sometimes offset by losses of pollinators that affect future crops.
And although neonics may appear to work in terms of reducing damage to the plant, in many cases this does not translate into higher yields at the end of the season. In one study, a neonic was found to reduce root injuries in corn, but this did not translate to a yield increase and associated economic benefit.
The questionable effectiveness of neonics and growing resistance of pest insects to these chemicals needs to be carefully weighed against the harm they are causing other organisms, and the loss of pollination and other services nature provides to agriculture.

Other Factors in Pollinator Decline

 

Insects are disappearing around the world. Recent estimates suggest that the current rate of decline may result in the extinction of 40 per cent of Earth’s insects over the next few decades. In Germany, for example, a 2017 analysis of 27 years of data found declines of 76 per cent of flying insects in protected areas. The authors of a 2018 study from Puerto Rico reported an insect decline of 98 per cent of ground foraging and 78 per cent of canopy dwelling arthropods (insects, arachnids and others with an exoskeleton) over 40 years. It’s thought that 40 per cent of invertebrate pollinators – especially butterflies and bees – are facing extinction. The International Union for Conservation of Nature Red List assessments indicate that 16.5 per cent of vertebrate pollinators are threatened with global extinction, increasing to 30 per cent for island species.

Habitat loss and conversion to intensive agriculture and urbanisation

Habitat change is a major driver of insect declines across the globe. Humans have altered insect habitat through forestry, the development of towns and cities, and by converting natural habitats to crops and rangeland for growing food. Agriculture has played one of the biggest roles in insect decline. Though in North America the highest rate of conversion of land to agriculture happened in the early part of the 20th century, major insect declines started when agricultural practices shifted from traditional farming with minimal use of chemicals to intensive, industrial-scale farming that involved the planting of monocultures, the recurrent use of fertilisers and pesticides, the removal of natural features (like hedgerows and trees) to make room for more advanced machinery, and the modification of surface waters to improve irrigation and drainage. The result was the loss of flowering plants, nesting sites and hibernation habitat for pollinators, including bumble bees, other wild bees, ground beetles and moth species that overwinter as larvae.

It is now well-established that changes in food and nesting resources due to habitat loss results in lower densities and diversity of foraging insects. However, the situation can be improved through a return to sustainable agricultural systems. Where urban centres have expanded into natural habitat and swallowed up agricultural lands, the creation of pollinator pathways that include urban parklands and gardens can help bring pollinators back.

“Pollinators are essential to our food supply, ecosystems and enjoyment of nature. There are hundreds of scientific studies that have demonstrated the serious harm of neonic pesticides and habitat loss on pollinators and other wildlife like birds and bats. We need to reverse the impacts if we are to avoid undermining the very ecosystems that support farming in Canada.”
David Browne PhD, Director of Conservation Science | Canadian Wildlife Federation

Biological factors (pathogens, parasites and invasive species)

Parasites and pathogens have been associated with the collapse of Honey Bee colonies in many countries and with declines in North American wild bees. For example, Varroa destructor mite and the Small Hive Beetle spread viral infections to managed Honey Bees. These viruses are not new to beekeepers, but they are affecting bees more severely since they are already weakened from exposure to pesticide contaminated pollen and nectar. Pathogens have also been spread to wild bumble bee populations through pathogen “spill over” from commercially-reared bumble bees that escape from greenhouses where they are brought in to pollinate. Better management of domestic bees can greatly reduce this effect.

Invasive alien species are those intentionally or accidentally introduced by humans beyond the species’ natural range. They quickly spread and grow in ways that impact other species and ecosystems. The results can be complex. For example, a generalist pollinator may benefit from an invasive plant that blooms frequently through the summer months. But if that invasive plant outcompetes a native plant relied upon by a pollinator specialist, the consequences could be disastrous. A recent review of the risks to pollinators from invasive species showed most interactions between native pollinators and invasive species are negative. While invasive plants can be a food source for pollinators, they can also transform pollinator diets, affecting their nutrition and posing risks for their health. Pollinating bees, for example, are very sensitive to the particular combination of nutrients found in the pollen of their preferred native plants. By feeding on invasive plants, pollinators may also be ignoring the pollination needs of native plants. Invasive pollinator species can spread pathogens and parasites to native pollinators (see above section). And some invasive species are predators of native pollinators. For example, the accidental introduction in 2004 of the predatory Yellow-legged Hornet into Europe from Asia directly threatens European Honey Bee populations.

Climate Change

The effects of climate change are complex and manifest in different ways depending on location. Though it may positively impact some insect populations in temperate regions, climate change is considered by some to be a significant driver of wild bee and butterfly declines. Pollinators in the Mediterranean region, such as the beetle Mylabris nevadensis, have been negatively impacted. Additionally, climate change is clearly the main driver of reductions in arthropods – many of which are pollinators – in a Puerto Rican rainforest. Average temperatures in the forest have risen by two degrees Celsius since the 1970s.

We must work diligently in the coming years to create habitat that will ensure pollinators can overcome current threats. This will require not only the voice of our supporters but also significant investment into the work that lies ahead!