Unsung backyard heroes and the threats they face: how ants (and other invertebrates) are impacted by environmental contaminants
- Aaron Fairweather
- Apr 15
- 4 min read
No matter where you look, plastics and pesticides are everywhere. In 2018 Europe was reported to have output 359 million tones of plastic into the environment. In 2022 an estimated 3.5 million tons of pesticides were input into the environment. Meanwhile, a fifth of all pollinator species in North America is at risk of extinction, and traces of plastics have been found in invertebrates as far as Antarctica. The link between the invertebrate decline on the planet and the rise in environmental contaminants has been shown time and time again. To what extent are invertebrates being impacted? How do we test these impacts? That is where my research comes in!
Ants are diverse, abundant, and everywhere! There are over 20,000 species globally, with 50 quadrillion individuals, and are found in every terrestrial ecosystem except Antarctica. We see them every day on our lawns, in agricultural fields, even in our homes. While some would regard them as pests, most ants are valuable soil nutrient cyclers, aerators, and pest predators. Ants are frequently more valuable to soil nutrition than earthworms! Ant species diversity is used as an indicator of agricultural health and productivity in Australia and some ant species are used for Integrative Pest Management in South America. For these reasons, ants make a strong non-target species for ecotoxicological testing.
My research with the Prosser lab focuses on testing the effects of pesticides and microplastics on ants. Prior research I conducted developed a novel way of testing environmental contaminants on ants in soil. Through this research, I found that a common North American species of field ant Lasius neoniger can be cultured from queens in the lab quickly, easily, and cheaply. In addition, I found that a common agricultural insecticide, imidacloprid, caused whole colony mortality in these non-target ants via soil contact exposure at concentrations a quarter of the recommended field application rate.
I am actively expanding on this research to other pesticides, and to include microplastics. I am investigating the impact of another common insecticide, cyantraniliprole, as well as various sizes of polyethylene plastic beads, on the overwintering of Lasius neoniger queens. Following this, I am testing what L. neoniger colonies do with polyethylene contaminated soils. Myself and an undergraduate research student, Speranza Martin, are investigating the impact of an insecticide, chlorantraniliprole, and fungicide, palladium, on the species interactions of Lasius neoniger and a common pepper aphid, Myzus persicae.
Preliminary results from these experiments suggest that there are insecticides which may not impact ant overwintering, and that ants interact with and move microplastics. L. neoniger and M. persicae interactions are predatory, and insecticides, fungicides, and mixtures significantly reduce aphid populations, but no more-so than ants do on their own.
Other invertebrates are regularly exposed to eco-contaminant microplastics and may face greater risk than ants. Giant American Millipedes, Narceus americanus, are a large species of millipede common to northeastern North America. They are some of the most valuable decomposers of leaf and wood material in this region, particularly in abundant areas such as the Niagara Gorge, Ontario, Canada.
My research with the Prosser lab has expanded to other invertebrates, and this millipede species presented an opportunity to test the impact of microplastics on a large decomposer.
A pool noodle may be discarded without a second thought after a pool party, but could have substantial environmental impacts. Pool noodles are made of polyethelene foam, which is used in insulation, textiles, toys, and car parts. I am testing whether Giant American Millipedes will eat pool noodle foam covered in biofilm, and what happens when they do. Preliminary results suggest they will abundantly eat this plastic, and it could disrupt their digestion of leaf litter.
These invertebrates are decomposers, nutrient cyclers, soil aerators, predators, and food for other animals. Without them, our ecosystems suffer. Protecting these animals by better understanding how the pesticides and pesticides we use impact them has a direct consequence to human health long term. The research I present here is the foundation of this understanding.
What can you do? Stay informed and ask questions! Pay attention to what pesticides and plastics you are using in and around your home. Also, understand where your waste is going, recycle, and minimize your impact by buying local ecologically conscious produced products. Consider planting native plant spaces on your property or farm. Consider the most up to date integrative pest management approaches for pest control. Understand the regulations and policies proposed by your governing body, and fight for policy and infrastructures that support the health of your community and environment, and include invertebrates in environmental risk assessment.
If you have any questions about what I do at the Prosser lab feel free to reach out at fairweaa@uoguelph.ca, or across any social media platform @ entobird.
If we lose soil invertebrates, we lose the land beneath our feet.
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