I tend to imagine that most people who love their gardens also love wildlife and want to do their best to help it thrive.

Of course, that’s not entirely true. Some people love a garden with a fake grass lawn. Some don’t care what it takes to make sure their vegetable patch is weed and pest free.

But most of us actually do care – and if you are one of those people and you’re still using weedkiller and pesticide, a new study from researchers at the University of Sussex, will surely make you think again. The report was titled “Habitat quality, urbanisation & pesticides influence bird abundance and richness in gardens” and highlighted the negative effects of pesticides on bird species.

It found, for instance, that the average house sparrow abundance was 12.1 per cent lower in gardens applying any pesticide, and 24.9% lower with glyphosate, and 38.6% lower with metaldehyde.

Vicky Allan: Climate science and data alerts us – but it's still about human stories

As its author, Dave Goulson (who also wrote a clarion call book on the “insect apocalypse”, Silent Earth) summed up the report’s significance: “There is now overwhelming evidence that pesticides harm wildlife and the environment.

“These chemicals are simply not needed in our gardens. Why would we spray poison where our children and pets play? We should simply ban urban and domestic pesticide use, following the example of France.”

Once-common, sparrows have dropped by 70% in the UK Meanwhile, garden pesticide use remains ubiquitous. The study found that 32% of the participating gardens used pesticides – though rates of use outside this self-selecting birdwatching group are likely to be higher. A 2019 online survey by the UK’s Health and Safety Executive (HSE) found that, out of the surveyed gardeners, 42.8% used pesticides.

The most widely-used pesticide in Goulson’s study was glyphosate. The call to ban this organophosphate isn’t, of course, fresh news. Other countries have already banned it and the WHO in 2015 described it as “probably carcinogenic to humans”.

Perhaps, however, what we should be paying most attention to is its impact on insects. Glyphosate, though a herbicide, has been found to inhibit the ability of bumblebees to keep their colonies at the right temperature.

It has been shown to impact on insect immune systems and to harm the gut microbiome in honeybees. Insects feed most birds and bats. They are pollinators and recyclers. What damages insect biodiversity damages us all.

Goulson’s study adds to a body of research that suggests that we have to look at the indirect impact of a chemical – its reduction for instance in food availability for birds – as well as its direct effects.

Yet still we in the UK are a very long way from banning it even from gardens. Glyphosate-containing Roundup is still sold in Wickes and Homebase. The Range sells a concentrated glyphosate weedkiller. I could go on with the list, but I’m in danger now of sounding like a supplier out to link you up with dealers for exactly the substances I want you not to buy.

Not only that, but this chemical looks set to be available in the UK for some years to come, in spite of being banned in other countries. The reason for this is that following Brexit, as part of the approval process, all those pesticides due to expire before December 2023 were extended for three years, to 2026.

Vicky Allan: For peat's sake! Scottish government's missed targets and false figures

A Ferret report last year found every Scottish council was still using glyphosate. Across the 31 (out of 32) councils that responded to their freedom of information request, they found that 40,250 litres of the weedkiller were used. Over 18,000 litres of this was applied by the biggest users, Glasgow, Edinburgh, Fife, Aberdeenshire and Aberdeen City.

And meanwhile, other pesticides have also been linked, through Goulson’s study, to falling bird numbers. These included the insecticide acetamiprid, the insecticide deltamethrin and the chemical found in slug pellets, metaldehyde.

The good news is that metaldehyde slug pellets were banned from sale or use last year.

But what about deltamethrin? Yes, you can still get it in products like Provanto ultimate fruit and vegetable bug killer, available at Wilko and online.

We need to put nature at the heart of gardening. As Dave Goulson puts it, “UK wildlife is in rapid decline, but our gardens can be a refuge for many species. Our new study shows that the way we garden has a huge influence on the number and variety of birds that live in our gardens.”

Some may be saddened at the idea that the perfect, easily-maintained neat garden is over. But better a wild and wonderful garden rich in biodiversity than one that looks perfect, but is dying.