Our Garden Pest Control Could Be Harming Bees
The threat that crop pesticides pose to bees has been discussed and debated heavily, but a new study reminds us that the products we use on our own gardens can have a significant impact on our pollinators too.
Researchers at Purdue University wanted to look at what other chemicals might be affecting our pollinators besides exposure to pesticides from agriculture.
To study this, the researchers examined three hives in different settings: a meadow, a field treated with neonicotinoids – thought to be one of the main culprits in pollinator die-off — and a cornfield where no pesticides were used. In total, around 30 families of plants were represented in the study.
Scientists then analyzed the pollen available to bees in these areas over a period of 16 weeks to determine whether it contained pollutants.
No matter where hives were located, most bees picked up pollen that contained large amounts of pesticides. For example, the hives in the meadow and pesticide-treated field yielded pollen with about 29 different types of pesticides, while the non-treated cornfield actually had slightly more at 31 types.
Unsurprisingly, the most common chemical traces were from fungicides and herbicides. Neonicotinoids featured heavily, but so did a chemical called pyrethroid. Both appear to have an effect on bees.
Neonicotinoids appear to be more damaging, but they are usually found only on farmland where they are used to treat crops. However, pyrethroids are present in over-the-counter pest control solutions that we might buy for our home gardens.
One one hand, pyrethroids are quite desirable, as they act fast and require low concentrations to kill so-called pest species. However, they bind quickly to soil and do not get washed away by rain, meaning that they persist in the environment
As a result, bees might actually be exposed to far more pyrethroids in our home gardens — and on a more frequent basis. In fact, the researchers were able to identify spikes of pyrethroids in the months of August and September, when many people spray to ward off mosquitoes and other pest species.
Researchers Christian Krupke and Elizabeth Long say their study — published in late May in “Nature Communications” — shows a significant risk to bees.
“Although crop pollen was only a minor part of what they collected, bees in our study were exposed to a far wider range of chemicals than we expected,” Professor Krupke explained. “The sheer numbers of pesticides we found in pollen samples were astonishing.”
Based on this study alone, researchers cannot say with certainty that exposure to these chemicals creates a problem for honey bees and other pollinators. However, it’s reasonable to consider chemical exposure as a potential factor in the pollinator decline recorded worldwide.
In addition to neonicotinoids and other insecticides, pests such as the varroa mite have contributed to ill health in bee colonies. Bee-friendly habitats have also been reduced, and climate change may further impact bee numbers by altering flowering seasons and creating less hospitable environments.
So what do the researchers recommend we do about this potential problem? ”If you care about bees as a homeowner, only use insecticides when you really need to because bees will come into contact with them,” Long asserted.
If you’d like to find out more about how to keep pests at bay with non-pyrethroids, Care2 has a few ideas for organic, homemade pesticides.
Photo credit: Thinkstock.