What if the real danger of glyphosate-based weedkillers isn’t what they kill — but what they quietly weaken?
We talk a lot here about human health, food residues, waterways, soil organisms, and the impacts on every living thing that comes into contact with glyphosate-based herbicides. But every now and then, a piece of research comes along that gently reminds us of something we often underestimate:
These chemicals don’t just touch crops and weeds.
They touch the creatures that make our ecosystems work.
A new peer-reviewed study in Scientific Reports has done exactly that. And although it focuses on a North American bumblebee species, its message is one New Zealand can’t afford to ignore — especially when our own food production, biodiversity, and pollination services depend on a delicate web of insects that never evolved to cope with chemical exposure.
So let’s talk about bumblebees — specifically what happens to male bumblebees when they encounter glyphosate-based weedkillers.
And why this matters far beyond one species.
A New Study on Glyphosate-Based Herbicides and Bumblebee Fertility
The research examined Bombus impatiens, a common bumblebee species used in scientific studies. Researchers exposed male bumblebees to a glyphosate-based herbicide you’d recognise instantly from any hardware store shelf.
And here’s what didn’t happen:
They didn’t die.
That’s usually where regulatory interest ends.
But something else did happen — something subtle, and far more concerning.
The exposed male bumblebees had about 34% fewer living sperm cells than the unexposed group.
Their bodies kept going.
Their reproduction didn’t.
For a species whose long-term survival depends on successful mating, colony development, and seasonal reproduction cycles, this isn’t a small effect. It’s a sign of biological stress that doesn’t show up in mortality statistics but shows up where it matters: the next generation.
If glyphosate-based weedkillers can alter reproduction in bumblebees, what might they be doing to other pollinators — including species we rely on heavily here in New Zealand?
It’s a question regulators aren’t asking.
But we should be.
Sub-Lethal Effects of Glyphosate on Bumblebees: Survival vs Reproduction
One of the most curious findings in the study was that bumblebee survival didn’t decline. In fact, exposed males lived slightly longer.
At first glance, that sounds reassuring. But when survival improves while reproduction collapses, something is out of balance.
The authors suggested that the bumblebees may be diverting energy away from reproduction and into basic survival — a physiological stress response often seen when organisms are exposed to harmful substances.
In other words:
They’re alive.
They just can’t reproduce properly.
It’s the kind of impact regulators routinely overlook because they tend to focus on lethal effects. But ecosystems don’t collapse because a species drops dead overnight.
They collapse when year after year, fewer offspring are born.
A Cross-Species Fertility Warning We Can’t Ignore
What makes this new bumblebee research even harder to shrug off is how familiar the pattern looks when you zoom out.
Just a few days ago, we wrote about what scientists are finding in human males exposed to glyphosate — and the parallels are uncomfortable.
Researchers have detected glyphosate in seminal fluid, sometimes at concentrations several times higher than in blood. Right beside it, they found markers of oxidative stress, widely recognised as a driver of sperm DNA damage, reduced motility, and poorer overall fertility.
Other studies have shown that glyphosate-based herbicides can affect hormone balance, mitochondrial function, and the health of developing sperm cells. None of these findings hit like a dramatic poisoning event — they’re subtle biological shifts that only become obvious over time.
And now we’re seeing a similar pattern in bumblebees:
a 34% reduction in living sperm cells after exposure to a glyphosate-based weedkiller, with no obvious signs of sickness or mortality.
Different species.
Different environments.
Same direction of effect.
When a chemical begins to show reproductive impacts across insects, animals, and humans, the question is no longer “Is this species-specific?”
It becomes:
Are we looking at a broader biological signature — one that points to how glyphosate-based weedkillers interfere with living systems in general?
Because if fertility is declining in more than one species after exposure — and especially at everyday, non-lethal doses — then this isn’t just about pollinators. And it isn’t just about people.
It’s about whether we’re witnessing early signs of a cross-species reproductive stressor that regulators have entirely failed to account for.
Both patterns point toward oxidative stress and cellular dysfunction as possible common threads — different species, same biological pressure points.
Why Bumblebee Fertility Loss Matters for New Zealand’s Ecosystems and Food System
New Zealand depends on a mix of pollinators:
- introduced honey bees
- introduced bumblebees
- and a wide range of native bees and insects
Bumblebees may not get as much attention as honey bees, but they’re essential pollinators — particularly for crops that require “buzz pollination” such as tomatoes, blueberries, peppers, and many specialty horticulture crops.
If a weedkiller affects reproduction in bumblebees, it raises broader questions:
What happens to honey bees exposed to the same chemicals?
What about native pollinators that haven’t been studied yet?
What about the knock-on effects to fruit, seed, and pasture production?
Our food system depends on pollination.
Our biodiversity depends on pollination.
And our economy — especially horticulture — depends on pollinators functioning as nature intended.
A 34% drop in living sperm cells isn’t a small blip.
It’s a warning.
Bumblebee Fertility Findings Reinforce Concerns About Glyphosate-Based Herbicides
One of the reasons this study matters is because it didn’t test pure glyphosate — the isolated chemical regulators prefer to focus on so they can claim “low toxicity.”
It tested a glyphosate-based herbicide formulation — the real product used in gardens, paddocks, orchards, footpaths, parks, and roadways.
These products contain:
- surfactants
- solvents
- preservatives
- adjuvants
- synergists
…many of which are more toxic to insects than glyphosate itself.
So when a study shows fertility impairment linked to an actual formulation, it’s telling us something important:
Real-world products behave differently from the pure chemical regulators continue to assess.
And that means we may be underestimating the ecological risk of glyphosate-based weedkillers — not just to bumblebees, but to any pollinator that encounters them.
Regulatory Blind Spots: Are We Missing Glyphosate’s Impact on Pollinators?
The biggest question this study raises isn’t just “Why did fertility drop?”
It’s “Why aren’t we measuring this?”
Regulators tend to prioritise tests that look for:
- death
- paralysis
- acute poisoning
But fertility?
Hormone disruption?
Developmental impacts?
Neurological or microbiome disruption?
These are the effects that quietly shape the future of a species.
And they’re rarely included in regulatory risk assessments.
We’ve seen the same pattern across multiple glyphosate studies: no dramatic instant harm, but clear disruptions to biological systems that only show up over time or across generations.
If bumblebees are showing reproductive harm, what does that mean for species we haven’t studied yet?
Pollinators as Indicators: What Bumblebee Fertility Tells Us About Glyphosate Risks
Ecologists often refer to certain species as “indicators” — organisms that reflect the health of the environment around them.
Bumblebees are excellent indicators because:
- they are sensitive to environmental changes
- they forage widely
- they encounter soil, foliage, and floral residues
- their health reflects broader ecological conditions
And for years, pollinators have been sending out subtle distress signals:
Reduced colony performance.
Lower reproductive success.
Altered foraging behaviour.
Weakened immune function.
This new study adds one more piece to the puzzle — and it’s a significant one.
If our pollinators struggle, our food systems struggle.
And if our food systems struggle, so do we.
So the question becomes less about whether one species in one study is affected — and more about whether we are comfortable ignoring the pattern emerging across many species and many studies.
What the New Bumblebee Study Means for New Zealand’s Future Glyphosate Use
While Bombus impatiens isn’t found in New Zealand, bumblebees worldwide share many of the same reproductive vulnerabilities seen across pollinator species exposed to pesticides. Studies like this provide early warning signals that may also apply to the pollinators we depend on here — including our commercial honey bees, greenhouse bumblebees, and native species.
New Zealand uses:
- honey bees for commercial pollination
- bumblebees for greenhouse crops and open-field horticulture
- native bees for many wild and indigenous ecosystems
All of them encounter glyphosate-based herbicides in some form.
Our agricultural systems rely heavily on pollinators.
Our horticulture sector relies even more.
And our biodiversity depends on species interactions we barely understand.
If glyphosate-based weedkillers can impair reproduction in bumblebees, then the precautionary principle says it’s reasonable to consider similar risks for other pollinators — especially when we have no comprehensive monitoring in place.
New Zealand cannot wait for a worst-case scenario to play out before asking whether our weedkiller habits are sustainable.
Where This Research Leaves New Zealand on Glyphosate and Pollinator Health
We now have evidence — again — that glyphosate-based herbicides can cause sub-lethal but biologically significant harm in non-target organisms.
This study doesn’t claim to represent honey bees or native bees.
It doesn’t need to.
It tells us that:
- not all harm shows up as death
- reproduction is a critical endpoint
- glyphosate-based formulations can disrupt biological systems
- pollinators are more vulnerable than we assume
- ecosystems can unravel without any dramatic “die-off” events
If we care about our food supply, our biodiversity, and the health of every species that keeps our ecosystems functioning, we cannot dismiss findings like this.
Maybe the bumblebees aren’t just reacting.
Maybe they’re warning us.
And the real question is:
Will New Zealand listen?
Resources & References
When regulators say glyphosate is “safe when used as directed,” they rarely mention research like this. These studies paint a very different picture — one where sub-lethal effects, endocrine disruption, oxidative stress, and reproductive damage show up consistently across species. Here’s the evidence worth reading for yourself.
Common herbicide impairs fertility but not survival in bumblebees (Bombus impatiens)
The 2025 peer-reviewed study showing a 34% reduction in living sperm cells in male bumblebees exposed to a glyphosate-based weedkiller.
Coenzyme Q10 Protects Against Glyphosate-Based Herbicide Testicular Damage
A 2024 study showing that glyphosate-based herbicides cause testicular toxicity, sperm damage, oxidative stress, and inflammation — with researchers noting that CoQ10 only mitigates the harm, not that the herbicide is safe. Reinforces concerns about male reproductive impacts.
Why Honey Tests Positive for Glyphosate
Explains how glyphosate enters New Zealand honey through environmental contamination, spray drift, and bee foraging pathways.
Healthy Honey — Glyphosate: A Contradiction
Examines the tension between “pure, natural honey” branding and the reality of glyphosate residues detected in retail honey.
Glyphosate — Bee Brain Disruption
Breaks down research showing how glyphosate can affect bee brain function, navigation, learning, and foraging behaviour.
Glyphosate Impact on Bees
A broad summary of scientific findings on how glyphosate-based herbicides affect bee health, behaviour, and survival.
Honey, Glyphosate & the Broken Social Contract
A commentary on what glyphosate contamination means for consumer trust in New Zealand honey producers and food safety systems.
Tutin vs Glyphosate — A Food Safety Standard Double Standard?
Highlights the regulatory inconsistency between strict controls on natural toxins like tutin versus permissive standards for glyphosate.
Glyphosate Honey Test Results — Batch 4
Your fourth round of independent honey testing, revealing real-world glyphosate residues in NZ honey brands.
Glyphosate and Male Fertility — What the Science Is Telling Us
Summarises emerging evidence showing how glyphosate exposure may affect human sperm quality, oxidative stress, and reproductive health.
The research listed here is just a snapshot of what scientists are uncovering. New studies are emerging every year, many echoing the same concerns. We’ll keep updating this list as the science evolves — because staying informed is our first line of protection.
Image Source & Attribution
We’re grateful to the talented photographers and designers whose work enhances our content. The feature image on this page is by Sandy Millar, of Auckland, New Zealand. You can find more of their work here: https://unsplash.com/@sandym10.
