Insects exposed to low levels of chlorothalonil suffer major reproductive harm. Its continued use threatens pollination and ecosystem balance.
New research from Macquarie University has revealed that a commonly applied agricultural chemical, used on Australian fruits and vegetables to combat fungal infections, is causing serious harm to beneficial insects essential for pollination and maintaining ecosystem balance.
Published in Royal Society Open Science, the study shows that chlorothalonil, among the most widely used fungicides globally, significantly disrupts insect fertility and survival, even at the minimal concentrations typically found on produce.
“Even the very lowest concentration has a huge impact on the reproduction of the flies that we tested,” says lead author Darshika Dissawa, a PhD candidate from Macquarie’s School of Natural Sciences.
“This can have a big knock-on population impact over time because it affects both male and female fertility.”
Reproductive effects appear at very low doses
The research team exposed fruit flies (Drosophila melanogaster) to concentrations of chlorothalonil that reflect typical levels found on crops such as cranberries and wine grapes. At even the lowest tested concentration, the flies experienced a 37 percent reduction in egg production compared to those not exposed.
According to supervising author Associate Professor Fleur Ponton, the severity of the decline came as a surprise.
Chlorothalonil remains widely used in Australia
“We expected the effect to increase far more gradually with higher amounts. But we found that even a very small amount can have a strong negative effect,” Associate Professor Ponton says.
Although banned in the European Union, chlorothalonil is extensively applied to Australian crops including orchards and vineyards, often preventatively when no disease is present.
The findings add to mounting evidence of what researchers call the “insect apocalypse” – a global phenomenon that has seen insect populations plummet by more than 75 percent in some regions in recent decades.
Call for reduced pesticide use and better regulation
“We need bees and flies and other beneficial insects for pollination, and we think this is an important problem for pollinator populations,” Associate Professor Ponton says.
The research highlights a critical knowledge gap in pesticide regulation, with fewer than 25 scientific papers examining chlorothalonil’s effects on insects despite its widespread use.
The researchers recommend more sustainable practices, including reduced application frequency to allow insect population recovery between treatments.
Reference: “Chlorothalonil exposure impacts larval development and adult reproductive performance in Drosophila melanogaster” by Darshika M. Dissawa, Ines Boyer and Fleur Ponton, 04 June 2025, Royal Society Open Science.
DOI: 10.1098/rsos.250136
Funding: Macquarie University
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11 Comments
I have noticed this near collapse here in Oklahoma. I used to work in Tulsa and commute for weekends back to Oklahoma City. By the time I would arrive at either location, my windscreen would be an impact mass murder soup of all sorts of insects. 50 years later, if you strike one bug while driving it’s a miracle. Bugs, even though they cause great damage, they are the underpinning of the biodiversity we enjoy on this planet. Their decline is a serious peril to life.
I don’t believe this at all i have walked in the woods my whole the bugs and ticks are 5x what they were 20 years ago… If this helps then good
Walking in the woods and studying national data from field research is not the same bro.
You believe that your isolated individual perspective trumps global scientific observation?
Again the agrochemical corporations are killing the planet and us. If you grew up on a farm and understand how everything is connected and that there are ways to combat fungus without killing all the insects. Who pollinate the flowers, control the pests, and breakdown the dead into fertilizer for the plants. When they can make a dollar they will do anything for it.
The paper advises some botanically derived fungicidals that don’t crazy kill bugs, their fruit fly exemplars included. They stop short of putting them in ya’ Amazon cart, too reasonably. (Peach Farmers, call me out wrong!)
He probably means his whole decade of life.
Not long ago you couldn’t walk through a field without a swarm of grasshoppers and other insects fleeing before you.
I can’t remember the last time I saw an adult grasshopper.
Maybe if we hadn’t killed most of them the ticks, fleas and mosquitoes wouldn’t be so prolific.
And, that’s the whole problem; when was the last time that you saw an ad for a grasshopper dating service?
So the chemical inhibits the fertility of insects. What does it do to the fertility of humans?
They don’t care one bit what it does to human beings. And they know exactly what it does to human beings. All they care about is the money. But believe me. God will take care of that when he returns.We will be held accountable for what we do to this earth.
Dumpsters for Apartment Complexes used to teem with flies in Summer, when I was much younger. In the last few years I’ve noticed that it’s no longer the case