Pressure on gardeners to ditch bug-killers known as neonicotinoids is set to increase – after a major study claimed a link to honey bee decline.

Neonicotinoids, often known as neonics, are chemical ingredients used in some garden and agricultural insecticides.

They are systemic, meaning that they’re absorbed into cells throughout a plant – making all parts poisonous to pests.

Last year, the EU ordered a two-year Europe-wide suspension of three neonics: imidacloprid, thiamethoxam and clothianidin.

Products such as Bayer’s Provado Lawn Grub Killer (imidacloprid) were withdrawn from garden centre shelves.

However, other neonic insecticides remain legal and approved for sale.

The latest probe, called the Worldwide Integrated Assessment (WIA) reviewed 800 studies covering birds, animals, soil, water and bees.

Global, independent scientists from The Taskforce on Systemic Pesticides concluded that neonics “pose a serious risk of harm to honeybees and other pollinators such as butterflies, and to a wide range of other invertebrates such as worms and birds.”

Vanessa Amaral-Rogers of charity Buglife said: “The evidence is clear: neonicotinoids are harming our pollinating insects and could cause damage to many other species and habitats.”

Nick Mole, of Pesticide Action Network UK, said: “We find it incredulous that DEFRA and the National Farmers’ Union have consistently towed the pesticide manufacturers’ line in claiming that these toxic pesticides present no threat to pollinators.”

Director of the Soil Association, Helen Browning, warned: “This overwhelming scientific evidence of the dangers of neonicotinoids follows a pattern. Classes of pesticides, previously claimed to be safe, are being found to be dangerous and subsequently banned.”

Manufacturers of neonics have always dismissed any link between the chemicals and bee decline.

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