By Pamela Sleightholm
Creating habitat with native plants is the best way to help pollinating insects. We’ve read the news and understand that they’re essential to our existence (about one-third of the food we eat depends on insect pollination). But why do they need help in the first place?
Five main factors are having a huge impact on pollinators - habitat loss, pesticides, parasites and pathogens, invasive species and climate change - each of them reducing their numbers and health. And when a species is weakened by one factor, they are much more susceptible to the others.
©Pollinator Partnership Canada
1. Habitat loss
Urban sprawl, human development, transportation infrastructure and even farming have destroyed the prairies, meadows and woodlands that pollinating insects need for food and shelter. Bees and wasps generally have short range for foraging – when they can’t reach the plants they need, their populations drop.
2. Pesticides
Neonicotinoids are commercial pesticides, still in use in Canada, that are having a huge impact on bees. For many bees, these insecticides are lethal. But even non-lethal exposure to neonics can change bees’ behaviours, immunology and reproduction dramatically (Pollinator Partnership, 2022).
3. Parasites and pathogens
Viruses, bacteria and parasites can be spread between pollinators and impact their abilities to forage, navigate, learn and socialize (Gomez-Moracho, et al., 2017). Though parasites and pathogens have always existed naturally, their impacts are exacerbated through habitat loss, pesticide use and stress.
4. Invasive species
Ornamental or human-food plant species that have been imported to Canada can disrupt local ecosystems. Some produce toxins that prohibit other plants from growing, some invasives cast heavy shade and some just push out the native species that pollinators need. Periwinkle, lily of the valley, Japanese barberry, hyacinth, garlic mustard, miscanthus and so many more disturb the balance of plants in the ecosystem and prevent the plants pollinators need from thriving.
5. Climate change
Insects and the plants they depend on evolved together. Historically, when a butterfly emerges from its chrysalis the nectar plants are ready for it. But climate change is throwing that out of whack. With warming temperatures, insects are emerging before the plants are ready for them and are not adjusting their ranges proportionately to changing climate (Dew et al., 2019; Kerr et al., 2015).
Sources:
Dew, R. M., Silva, D. P., & Rehan, S. M. (2019, March 6). Range expansion of an already widespread bee under climate change. Global Ecology and Conservation. https://www.sciencedirect.com/science/article/pii/S2351989419300599
Gomez-Moracho, T., Heeb, P., & Lihoreau, M. (2017). Effects of parasites and pathogens on bee cognition. http://www.mathieu-lihoreau.com/. http://www.mathieu-lihoreau.com/wp-content/uploads/2017/08/Gomez-Moracho-et-al.-2017-Ecol-Entomol.pdf
Health Canada. (2021, June 29). Neonicotinoids in Canada. Canada.ca. https://www.canada.ca/en/health-canada/services/consumer-product-safety/reports-publications/pesticides-pest-management/fact-sheets-other-resources/neonicotinoids-in-canada.html
Kerr, J. T., Pindar, A., Galpern, P., Packer, L., Potts, S. G., Roberts, S. M., Rasmont, P., Schweiger, O., Colla, S. R., Richardson, L. L., Wagner, D. L., Gall, L. F., Sikes, D. S., & Pantoja, A. (2015). Climate change impacts on bumblebees converge across continents. Science, 349(6244), 177–180. https://doi.org/10.1126/science.aaa7031
Wojcik, V., Morandin, L., & Law, K. (2022). Protecting pollinators from pesticides in apples. Pollinator Partnerships Canada. https://pollinatorpartnership.ca/assets/generalFiles/Apple-Pollinator-Guide-English.pdf