The frosted “curtain” rises, lights dim and the finger-sized insect watches as computer generated images are projected on the private viewing screen — minus the sound and popcorn.

Expanding black discs flash across the screen, which from the locust’s perspective look like a black curve ball coming right at it.

Just like a baseball batter waiting to swing, it stimulates a reaction to move away from the black object being thrown at its head.

The production is all part of a novel technique being used by researchers at the University of Saskatchewan to measure the locust’s escape behaviour while under the influence of a new sulfoxamine pesticide being tested called sulfoxaflor.

The goal is to compare the effects of sub-lethal doses of two families of pesticides (neonicotinoids and sulfoxamines) used in agriculture to observe the effects of insect behaviour and insect neurobiology.

For several years Jack Gray, a biology professor and expert in neural control of animal behaviour, as well as Rachel Parkinson, a former U of S PhD student, have been studying how neonicotinoids alter the vision and motion detection of migratory locusts.

It’s the same species of locust that is wreaking havoc in East Africa, potentially endangering economies in a region heavily dependent on agriculture for food security.

Neonics are widely used in crop production as a seed treatment, but they are also controversial, particularly when it comes to their possible effect on birds and insects.

The controversy has motivated researchers to look for alternatives.

In their most recent study, Gray and Parkinson have found that at low dosages, sulfoxaflor is less toxic than the currently used neonic imidacloprid, which at non-lethal doses on insects and other species needed to be investigated further.

The results of their latest study were recently published in the Proceedings of the National Academy of Science.

“What we’ve found suggests that this sulfoxamine is less toxic, which could have less of an impact on a non-target insect potentially — meaning one that’s not an economic pest,” said Gray.

In an effort to compare nervous system activities, researchers embed electrodes into the thorax of the locust and then feed it a small amount of pesticide.

They found that the two pesticides are equally fatal at the same dose.

The pesticides have similar lethal dose (LD) 50 values, which is the amount that kills 50 percent of animals.

“It’s a measure that you can compare different chemicals and it gives you an idea of one might be more toxic than another,” Gray said.

“So if you have a lower LD 50, it means it’s more toxic because it takes less of it to kill 50 percent of the test subjects that you have.”

However, it appears that sulfoximine at lower doses is considerably less toxic than the neonicotinoid pesticide.

“As you increase the concentration, you get more and more animals dying until you kill off 50 percent of your population,” he said.

“With the sulfoxamine at the low doses, they’re all surviving, then suddenly half of them die. So it’s like at the low dose, there’s much less toxicity. It’s not having an effect on them.”

The scientists also compared the two chemicals to observe the locust’s escape behaviour inside the dome theatre, which in this case is a jumping action.

“What we’ve found is that with the neonicotinoid, consistent with our previous work, is that at low doses, even though it was not killing the animals, it was severely impairing their ability to jump away from something,” he said.

“With the sulfoxamine at those same low doses, the animal was responding, the locust was jumping away. At low doses neonicotinoids prevent it from jumping. Sulfoxamines do not. So sulfoxaflor seems to be less toxic, it kills fewer of them and has less of an effect on their behavior through their ability to jump away from an object.”

Gray said parts of the nervous system are similar across many species of insects when it comes to self-preservation.

“In fact, it’s even similar in amphibians, reptiles, mammals and probably us because it seems in an evolutionary sense to be one of the best ways to detect something coming at you,” he said.

And because locusts are a well-studied species, inferences can be made about what could happen in other kinds of species exposed to a non-lethal dose, such as bees.

Gray plans to study bees this summer using similar techniques that he has learned with locusts.

However, previous research indicates bees respond differently to moving objects compared to locusts.

They tend to embrace or match a particular movement as a way of reducing that motion on their eyes, which helps them steer their way to find nectar or fly home to their hive.

“That’s a strategy they use when they’re out foraging. They want to keep their flight track straight when they’re navigating and trying to find things,” he said.

“So that’s a behavioral assay that we’re going to use to say, if you are treating the bees with some pesticide … does it impair their ability to track that rotation? If it does, that suggests that it’s severely impairing their ability to navigate.”

The study, which will be published tomorrow in Science, a highly regarded scientific journal, has concluded that imidacloprid is a threat to songbirds.

White crowned sparrows that consumed seeds coated with the insecticide lost weight and the exposure halted their migration, the scientists found.

“We saw these effects using doses well within the range of what a bird could realistically consume in the wild — equivalent to eating just a few treated seeds,” said Margaret Eng, a post-doctoral fellow in the University of Saskatchewan’s Toxicology Centre and lead author of the study.

“Both of these results seem to be associated with the appetite suppression effect of imidacloprid. The dosed birds ate less food, and it’s likely that they delayed their flight because they needed more time to recover and regain their fuel stores.”

Imidacloprid is a neonicotinoid, a class of insecticides used on tens of millions of acres in Canada. Neonics are applied to almost every corn and canola seed in Canada and a portion of soybean seeds.

The study on songbirds comes at a time when Health Canada is making a final decision on the safety of neonicotinoids.

Health Canada has proposed to phase out all agricultural uses of neonics because of evidence showing the insecticides were accumulating in ponds, creeks and other water bodies near agricultural land.

Health Canada has argued the neonics are reducing the population of midges and mayflies in water bodies, potentially harming birds and other animals who depend on those insects for food.

“The department continues to evaluate the potential risks to aquatic insects from the use of neonicotinoids,” Health Canada said earlier this year.

“Current research shows that these pesticides are detected frequently in water bodies at levels that could be harmful to certain aquatic organisms. The department expects to report on its findings at the end of 2019.”

Normally, proposed decisions on pesticides usually become final decisions at Health Canada.

However, data from water testing done in 2017 and 2018 indicated that researchers were finding tiny amounts of neonics in water bodies. Based on that new data, some observers believe Health Canada might back away from its neonic ban.

The U of S study may force Health Canada to think longer and harder about neonicotinoid safety.

“Migration is a critical period for birds, and timing matters. Any delays can seriously hinder their success in finding mates and nesting, so this (study) may help explain, in part, why migrant and farmland bird species are declining so dramatically worldwide,” said Christy Morrissey, A U of S toxicologist and senior author of the study.

U of S and York University researchers studied sparrows at a location in southern Ontario, a stopover during the spring migration.

They exposed the sparrows to small doses of imidacloprid and used a tagging technology to track the impact on the birds. The sparrows’ body composition was measured before and after exposure, and researchers also tracked the birds’ movements in the wild.

“Birds given the higher dose of the pesticide lost six percent of their body mass within just six hours. That one dose also caused birds to stay 3.5 days longer, on average, at the stopover site before resuming their migration, compared to control birds,” the U of S said in a news release.

This is the first study on songbirds exposed to neonicotinoids in the wild.

In 2017, Morrissey and Eng looked at captured sparrows and what happened when the birds ate imidacloprid-coated seeds

The results were similar to the latest study. The scientists concluded the neonic altered the birds’ appetite and sense of direction.

“These chemicals are having a strong impact on songbirds,” Eng said in 2017. “We are seeing significant weight loss and the birds’ migratory orientation being significantly altered.”

The Western Producer contacted Crop Life Canada, which represents the crop protection industry, to respond to the songbird study. A CropLife rep said the organization would comment but that no one was immediately available.

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Twelve months have passed since the announcement, but Canadian farmers who use the insecticide will have to wait another year to know if it’s banned or not.

“Health Canada is reviewing an extensive amount of data and information, including recently submitted water monitoring data,” a Health Canada spokesperson said.

“Once this information is reviewed, the proposed decisions will be subject to a public consultation period and final decisions are anticipated by December 2018.”

Health Canada’s Pest Management Regulatory Agency has proposed phasing out agricultural and outdoor uses of imidacloprid over three to five years. The PMRA said the phase-out is necessary because the insecticide was accumulating in water near agricultural land. 

The concentrations in water were reportedly putting aquatic insects at risk and threatening animals that rely on those insects for food.

The mode of action of imidacloprid is similar to two other neonicotindoids: clothianidin and thiamethoxam. Those products are used as a seed treatment on nearly every canola and corn crop grown in North America and a portion of the soy crop. 

PMRA scientists are also reviewing those insecticides to determine if they threaten aquatic life.

A number of agricultural groups have said banning imidacloprid is an extreme response because other policies could limit the use of the insecticide and reduce the threat to aquatic insects. 

Many growers depend on the Bayer product for insect control. Fruit, vegetable and potato producers are the main users of imidacloprid, but prairie growers use it on wheat crops to control wireworm.

The PMRA is going slow with its decision on imidacloprid, which gives scientists time to publish new research on the insecticide.

In November, toxicologists at the University of Saskatchewan released a paper on imidacloprid and songbirds in Scientific Reports.

The scientists fed canola seed coated with imidacloprid to white-crowned sparrows. They observed detrimental effects in birds that consumed only four canola seeds.

“These chemicals are having a strong impact on songbirds,” said Margaret Eng, a post-doctoral researcher who led the U of S study.

“We are seeing significant weight loss and the birds’ migratory orientation being significantly altered.”

The toxicologists said exposure to imidacloprid could compromise the health of songbirds and their ability to reproduce.

A spokesperson for Bayer said the study is misleading because it doesn’t represent real world conditions for white-crowned sparrows.

“The repellent properties of the (insecticide) seed treatment would normally deter birds from ingesting whole canola seeds treated with imidacloprid,” said Paul Thiel, vice-president of product development and regulatory science for the crop science division of Bayer in Canada. 

“Previous studies of caged birds indicated a lack of interest in imidacloprid treated seed if other food sources were available.”

Thiel said imidacloprid is rarely used as a seed treatment for canola, reducing the chance of birds eating such seeds.

A Health Canada spokesperson said PMRA scientists are considering the U of S study.

“It is too early to tell what impact it may have on the final decision.”

In a release, the NFU said it backs Health Canada’s proposed phase out of imidacloprid, a neonicotinoid insecticide used on many Canadian crops.

“We believe this proposed decision is a positive step and we fully support it,” the NFU said in a submission to Health Canada. “We urge (government departments) to promote alternative, less toxic insecticides and non-chemical agriculture techniques for the management of insect pests in general.”

In November, Health Canada surprised farmers and a few scientists when it proposed phasing out imidacloprid over three or five years

Scientists with Health Canada’s Pest Management Regulatory Agency determined that levels of imidacloprid in water bodies near agricultural land are unacceptably high, which is putting aquatic insects at risk and a threat to animals that depend on those insects for food.

The Bayer insecticide is used on wheat and other crops, but it is applied primarily to greenhouse crops, fruit, vegetables and potatoes in Canada.

Imidacloprid, once the most popular insecticide in the world, is a neonicotinoid, a class of insecticides applied as a seed treatment to almost all corn and canola planted in North America and a portion of soybean acres.

Neonics, as they’re commonly known, have become controversial. They’ve been linked to bee deaths and bee colony losses. In 2013, the European Commission banned the use of neonics in an effort to protect bees.

The NFU shared its thoughts on imidacloprid as part of Health Canada’s consultation for its proposed phase out.

The NFU’s stance isn’t a surprise. In 2013 the farm group called for a ban of all neonicotinoid seed treatments, citing a risk to bees and ecosystems.

In its submission on imidacloprid, the NFU said a ban is the only option because cutting its use won’t protect aquatic insects or the broader ecosystem.

“Imidacloprid moves with water in the soil and only a small amount of the chemical is absorbed into target plants,” the NFU wrote. “The grower cannot control the movement of the chemical following application. PRMA must phase out imidacloprid for agriculture use rather than attempt to regulate its use by amount, timing, location and crop.”  

Health Canada is accepting comments on its proposed ban of imidacloprid until Feb. 21.

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A representative of the Ontario Fruit and Vegetable Growers’ Association said Health Canada’s proposal to ban imidacloprid, a Bayer insecticide, is a blunder.

“In my humble opinion, if it’s like anything they (Health Canada) have produced in the last couple of years, there will be flaws,” said Craig Hunter, research and crop protection specialist with the association.

“It (imidacloprid) has a really good record, and this whole thing was done in total secrecy,” he said.

“I haven’t seen anything that would lead me to say that the use that’s on the label is either causing a problem or is unsustainable.”

Health Canada issued its plan last week to ban imidacloprid, a neonicotinoid insecticide widely used by fruit and vegetable growers across the country.

Health Canada said the ban is necessary because water bodies near agricultural land have unacceptably high concentrations of the insecticide. The levels of imidacloprid are a risk to aquatic insects, such as midges and mayflies, and animals that rely on those insects for food.

Hunter said imidacloprid, a Bayer product, was once the most commonly used insecticide in the world. Fruit and vegetable growers in Canada apply the product on crops such as field tomatoes, sweet corn and peas.

“It’s used on a great many fruit and vegetable crops and ornamentals.”

The Bayer Canada website says imidacloprid has been an “important product for potato growers for over 10 years.”

Many potato producers apply it in the soil or as a seed treatment to control beetles and other pests.

Hunter said the case for a ban should be definitive, considering how Canadian growers of special crops are dependent on the insecticide.

“I haven’t seen enough proof that the levels they’re finding, in the environment, are in fact real, that (the results) are, in fact, representative of all the use areas. And most importantly, even though they claim they have some numbers, they made their determination on the basis of a model,” he said.

“They put numbers into a model and then said it was unsustainable.”

Health Canada said in a summary of its decision that it relied on environmental modelling and data from water bodies.

“Robust environmental monitoring from several areas of intense agricultural activity in Ontario and Quebec further support these findings as imidacloprid is detected frequently in surface water at levels well above concentrations that may result in toxic effects to insects. These regions include both outdoor mixed agricultural uses (for example, potatoes and vegetables) as well as greenhouse uses.”

Hunter, who has asked Health Canada for its complete report on imidacloprid, said it’s difficult to replace such a chemical because specialty crops are a relatively small slice of agriculture.

“It’s a huge deal for growers of all the minor crops in all of Canada because a registrant who may already have a product (insecticide) registered for corn, canola, soybeans … would have to spend a lot of their own money to develop the data to register (the insecticide) for all our (specialty) crops,” he said.

“It (a ban) also means increased use of other pesticides, maybe not as effective. The net environmental (impact) could be higher.”

Horticultural producers decry neonic ban

Water monitoring data for Health Canada’s evaluation of imidacloprid came mostly from Ontario, Quebec and Saskatchewan. Based on that testing data, imidacloprid concentrations were higher and exceeded safe thresholds for aquatic insects more often in water bodies near:

• greenhouses in Ontario
• vegetable crops in Ontario (imidacloprid applied as a seed treatment, foliar spray and soil applications)
• potato and mixed vegetable crops in Quebec (applied as seed treatment, foliar spray and soil applications)
• Health Canada said risk to aquatic insects isn’t associated with a particular method of application, but monitoring data is likely an “underestimate of actual exposure, as sampling typically does not capture peak concentrations.”

Source: Health Canada

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