The introduction of neonicotinoid insecticides in the 1990s allowed us to simplify agricultural crop systems,(1,2) but it was followed by widespread environmental contamination and extensive loss of biodiversity.(3)
Think about how many bugs you used to be able to find on a car windscreen after a long drive, and just how rare that phenomenon is now! This dramatic loss of insects is only the tip of the iceberg when it comes to species decline related to environmental contamination.(3)
Increasingly, contamination of wetland ecosystems is being detected, and this has caused a growing concern for aquatic species such as amphibians(4). Approximately 70% of amphibian species are experiencing population decline, which may be due to one or several of the following factors: habitat loss, overexploitation, environmental pollution, climate change and the amphibian chytrid fungus disease.(5,6)
Where are Neonics?
Neonics are systemic, and in agriculture this helps them to be transported throughout the whole plant – the roots, the leaves and even the flowers.(7) But, while they are water-soluble, they do not easily biodegrade, and this leads to their persistence in the environment.(4) Through systemic and persistent use of neonics, pests can develop a natural resistance. In fact, the first neonics were developed throughout the 1980s after many agricultural pest insects had developed resistance to the insecticides used at the time.(7)
Which products contain neonics?
At last count, there were seven different neonics commercially used worldwide.(7) In Australia, these can be found in over 500 products sold at many of our favourite and well-frequented stores.
Imidacloprid, which is the most commonly used neonic, can be found in brands such as Amgrow, Advantage, Advantix, Advocate, Aristopet, Brunnings, Confidor, Exelpet, Exi-flea, Maxforce, Moxiclear, Neoveda, Roachkill, Searles Conguard, Sharp Shooter, Surefire, and many, many more.(8)
Other neonics can be found in products such as Accensi, Agita, Defender, Farmalinx, Purina, Seclira and Resolva (to name but a few).(8)
How are amphibians exposed to neonics?
Enormous amounts of neonics are applied to crops worldwide, and a substantial portion ends up contaminating the surrounding environment.
Contamination can take the form of aerial spraying, direct release into soil from coated seeds that are planted, and ground runoff into nearby water sources.(19) Neonics are soluble in water, and have been detected in water samples from streams, rivers, groundwater, reservoirs and wetlands all over the world.(16,19,20)
Amphibians can be found in wetland habitats throughout their different stages of development, and during growth, breeding and reproduction, which increases their exposure to potentially harmful chemicals.(21) These creatures have very thin, permeable skin, a special feature that allows air and water to enter their bloodstream, helping to regulate the amount of essential nutrients and chemicals within their bodies.
Unfortunately, it also makes amphibians more susceptible than many other creatures to pollution,(22) particularly contamination of aquatic ecosystems.
The effect of neonic exposure in amphibians Neonicotinoids get their name from their similarity to the chemical nicotine, and they block the same neuronal receptors in the body. Neonic pesticides are more effective at blocking these receptors in insects than in mammals and amphibians,(1,4,21) and is why they are approved for use in some countries as an insecticide.
Because of the difference in how the neonics affect amphibians and insects, amphibians are less likely to be directly killed by exposure to neonics. However, lower (or ‘sublethal’) doses can have also negative effects on amphibian populations.(23) There are currently only a limited number of scientific studies that have investigated the effect of neonic exposure on amphibians (but there are unfortunately none in Australia). Of these, some have found no negative effect on specific frog species, while others have found that neonic exposure increases the rate of tadpole death(24), impairs movement in tadpoles(25) and reduces the ability of some frog species to respond to predators(21).
Because the studies that have already been done show that some frogs are more affected by neonics than others, it’s even more important that research is done in Australia in our native amphibian species. That way, we can really understand the effects the neonics are having on amphibian in this country.
While there is still a lot that is unknown, the science indicates that neonic exposure could be harming amphibian populations and contributing to their decline worldwide. From our experience at the Frog Safe frog hospital in Northern QLD, we believe neonics have a devastating impact on our frog populations in Australia.
Why does the frog hospital suspect neonics are contributing to frog decline?
At Frog Safe, we have been diagnosing frog ailments since our doors opened in 1998. Since then, we have received more than 3,400 sick frogs with problems ranging from malformations and cancer to parasitic overloads and opportunistic pathogens due to immune failure. We have kept a public record of cancer diagnoses on our website – you can find this at https://www.frogsafe.org.au/disease/cancer.shtml
It was shortly before our official opening that many households around Cairns started to find sick and dead white-lipped tree frogs in their gardens. Shortly before this was the introduction of the neonics to Australia (approx. 1993–1996). While this is a case of correlation rather than causation, Dr Francisco Sánchez-Bayo, an Honorary Associate at Sydney University, supports our theory that neonics are contributing to the decline in frog populations.
In a personal communication, Dr Sánchez-Bayo told us:
“Some neonics (e.g. imidacloprid and clothianidin) impair the immune system of creatures such as bees, mussels, fish and birds. Essentially, the insecticide mimics a protein that is involved in the regulation of the immune system, stopping the T cells [a type of specialised immune cell that helps fight pathogens] from doing their job when an infection enters the body. This mechanism of immune suppression can occur in all types of animal, across vertebrates and invertebrates, so one can expect that neonics would induce immune suppression in frogs as well.”
He also highlighted that “The evidence so far refers to bees(26) only because they are being investigated in depth for obvious reasons [their importance in crop pollination around the world].”
Importantly, Dr Sánchez-Bayo believes that “There is no doubt that if an investigation using frogs was carried out it will give us the same answer: neonic use increases susceptibility of frogs to infections because the chemicals dampen their immune system.”
The effect of chemical combinations
Neonics are only one small part of the cocktail of chemicals that pollute the environment. The effect of a particular neonic on a given species is usually tested in isolation, which means that there’s still a
lot we don’t know about the real-world impact of chemicals combining in water run-off.
Based on very limited laboratory research on neonic combinations, the effects are predicted to be similar or worse than the toxicity of an individual neonic.(27) Only with more research will we find out the true impact of neonics, and environmental pollution in general, on beneficial animals such as amphibians.
How are other animals affected by neonics?
The majority of media and research attention in this area has focused on the impact to honeybees due to their importance in crop pollination around the world, as well as increased reports of the devastating phenomenon known as Colony Collapse Disorder.
Most of the research on the effect of neonics on bees has been done in Europe and North America using the Western honeybee, Apis mellifera.(28) However, in an article on The Australian Beekeeper, NSW beekeeper Jeffrey Gibbs reports that honey bee populations in Australia “are in crisis”, and that bee diseases in Australia are more prevalent now than in recorded history. From the studies done elsewhere, there is a consensus among beekeepers that neonics are causing harm to honeybees, and Jeffrey believes the situation must be no different in Australia.(9,29) Honeybees are most often exposed to sub-lethal doses of neonics, and this occurs via the pollen and nectar of treated plants (remember, the neonics are systemic!). While this is not immediately fatal to the bee, sub-lethal doses can negatively impact flight, mobility, brain development, learning, memory, orientation, reproduction and the ability to fight pathogens and parasites.(23,30)Mass die-off events in honeybees have been recorded, and scientists have linked some of these with exposure to neonic-containing dust clouds that are produced when neonic-treated seeds are being sown.(30) Despite many years of research, there is still debate around the specific effects of neonics on bees.(28) Nevertheless, the evidence produced so far has provided a strong link between neonic use and bee declines, and has prompted several countries to take action by restricting or banning neonic use.
Pesticides, including imidacloprid, have been detected in marine environments around Australia, including the Great Barrier Reef(16). To date, a small amount of evidence suggests that coral reefs might be affected by this contamination.(16) In one scientific study, a coral species that was exposed to imidacloprid had a reduced ability to heal wounds, which could increase its vulnerability in the wild to disease and algal overgrowth.(31)
Birds can be exposed to neonics though eating treated seeds or affected prey. Scientists have found that some farmland birds eating treated seeds left on the surface on fields have died within a couple of weeks. In other studies, birds exposed to sub-lethal doses of neonics have suffered organ toxicity, or had issues with their immune system, growth, development or reproduction.(23) Birds that eat insects can also be indirectly affected by neonic use; Dwindling insect numbers lead to a reduced food source.(23)
Humans can be impacted by direct exposure to neonics (either from direct contact by inhalation or from eating contaminated fruits and vegetables). At high enough concentrations, these chemicals can affect the nervous system, and organs such as the liver, kidney and thyroid. Because of their toxicity, there are lower levels of neonic contamination that are deemed acceptable on fruit and vegetables – but these levels differ from country to country. In addition, the impact of long-term exposure to neonics is largely unknown.(14)
We can also be impacted indirectly via the negative impact that neonics have on ecosystems and ecosystem services, which includes:
As well as providing these services, healthy ecosystems also hold cultural significance for humans, and can attract visitors from near and far for their aesthetic value and recreational opportunities (e.g. tourism and improving mental and physical health).(23)
Banning neonic use worldwide
Largely due to the threat posed to bees and other pollinators, and the devastating consequence pollinator decline could have on global and local food security, several countries have banned the use of some neonics. The European Union severely restricted the use of clothianidin, imidacloprid and thiamethoxam in 2018. These three commonly used pesticides are now not allowed to be used outdoors on bee-attractive crops. (They are still allowed in permanent greenhouses, on some crops after flowering and on winter cereal crops.)(32) France placed a full ban on the use of these three insecticides, and additionally banned the use of acetamiprid and thiacloprid.(33,34) In 2019, Canada announced that they would phase out (over 3 years) the use of clothianidin, imidacloprid and thiamethoxam on bee-attractive crops, and add label information to minimise the exposure of pollinators when seeds are sown.(35) At the start of 2020, Fiji also banned the use of imidacloprid in recognition of its negative effects on bees.(36) In the USA, the Environmental Protection Agency (EPA) have implemented a suite of restrictions on neonic use in order to protect pollinators. These include prohibiting the use of certain neonics when bees are being used in pollination services, and postponing approval of new outdoor neonic products until pollinator risk assessments have been completed.(37) In January 2020, the EPA released additional suggestions to further reduce the environmental impact of neonics.(37) Australia’s position on neonicotinoids The Australian Pesticides and Veterinary Medicines Authority (APVMA) state that “the available scientific information indicates that managed and wild honeybee populations are not in decline in Australia”. Based on this information, neonics continue to be used in Australian agriculture. In November 2019, the APVMA began a new review of neonic insecticides within the scope of environment and worker safety. This is because new environmental risks have been identified. The review is currently underway and will not conclude until August 2023.(38)
Jeffrey Gibbs, a NSW beekeeper, highlights in his article Neonicotinoids In Australia (published on The Australian Beekeeper website) that despite the Australian government claiming that the honeybee population is not in decline, the APVMA (Australian Pesticides and Veterinary Medicines Authority) reported a decline of 81,765 hives between 2006/07 and 2014. (29) Gibbs also mentions that in the USA, a group of American beekeepers and stakeholders sued the US Environmental Protection Agency in 2013 over approving the use of one of the neonics based on inadequate data. Perhaps for the government to change its mind on neonics in Australia, similar pressure needs to be maintained. (29)
Reducing your use of neonics
After France banned five of the commercially used neonics, a neonicotinoid working group performed a thorough assessment of available alternatives to the pesticides. They found that the neonics could be replaced in 96% of cases, with non-chemical alternatives available 78% of the time.(39) Your everyday use of these pesticides can be reduced using a two-pronged approach: using neonic-free household pest control and supporting neonic-free farming.
Neonic-free home pest control
Many neonic-containing products are used by people in their own homes to control pests such as cockroaches, spiders, fleas and ants. It’s good practice to always check product ingredients lists and avoid buying products that contain neonics. You can also contact local hardware and garden supply stores and lobby them to remove neonic-containing products from their shelves. The best non-toxic ways to keep pests out of your home include blocking up access points, keeping indoor areas clean, emptying rubbish bins regularly, keeping food in sealed containers, and regularly inspecting any potential pest hiding places (e.g. under cupboards, in wall cracks and in moist areas).(40) If you need to get rid of termites or paper wasps, remember that they don’t like lemongrass essential oil. Use this on wooden furniture or cabinets to protect them, and add the oil to refined coconut oil to rub down decks and railings. Be careful not to get the oil on your skin as it will burn! For loads of easy, effective and environmentally friendly cleaning and pest control tips, download our factsheet, ‘Some simple ways to reduce your use of chemicals’. A comprehensive guide to pest control methods and products that reduce pesticide use can also be found online in the IPM Practitioner’s 2015 Directory of Least-Toxic Pest Control Products (http://www.birc.org/Final2015Directory.pdf).
While buying direct from organic produce growers in your local area is the best way to support neonicotinoid-free farming, this is not a feasible option for everybody.
Some other ways to support the reduction in neonic use include -
And don’t forget, you can spread the word! Tell your family, friends and neighbours about the negative effects of neonics on the amphibians and the environment, and how they can reduce their use of neonics.