Insecticides kill insects, it’s what they are designed to do — so it seems fairly obvious that scientists can (and do) link insecticide use to the decrease of certain beneficial insects, such as honeybees. What is less obvious is how fungicides impact insects. Fungicides don’t target insects and were thought to be fairly ‘safe’ but a recent article published on sciencedaily.com shows this may be to the contrary.
A Cornell-led team of scientists analyzed two dozen environmental factors to better understand declining bumblebee populations. They expected to link it to stressors like changes in land use, geography or insecticides. Instead, they found a shocker: fungicides, commonly believed to have no impact.
Chlorothalonil, a general-use fungicide often found in bumblebee and honeybee hives–may negatively affect bee health.
While fungicides control plant pathogens in crops, the bees pick up their residue when foraging for pollen and nectar. As farms use both insecticides and fungicides, scientists begin to worry about the synergistic effects. Most fungicides on their own are relatively nontoxic to bees, but many are known to interact synergistically with insecticides–greatly increasing their toxicity.
Chlorothalonil has been linked to stunted colony growth in bumblebees and an increased vulnerability to Nosema, a fatal gut infection in bumblebees and honeybees. Bees contribute more than $15 billion to the economy in the United States – with roughly half of crop pollination being done by bumblebees and wild bees.
Read more about this story at Science Daily.
Cornell University. “Tumbling bumblebee populations linked to fungicides.” ScienceDaily. ScienceDaily, 14 November 2017. <www.sciencedaily.com/releases/2017/11/171114195041.htm>.