- A widely-used class of insecticides called neonicotinoids has contributed to the large-scale and long-term decline of wild bees, according to research unveiled Tuesday.
- In five of the species, including the spined mason and furrow bees, the chemicals accounted for at least 20 per cent of local population extinctions, researchers estimated.
- And compared to bees that foraged on a wide range of flowers, decline was three times more pronounced among species – such as the buff-tailed bumblebee – that feed regularly on the rapeseed.
- The results also bolster small-scale and short-term studies that have previously fingered neonics as a culprit in bee decline, especially species bred for pollination and honey production.
- Unlike contact pesticides – which remain on the surface of foliage – neonicotinoids are absorbed by the plant from the seed phase and transported to leaves, flowers, roots and stems.
- They have been widely used over the last 20 years, and were designed to control sap-feeding insects such as aphids and root-feeding grubs.
- Neonics are deemed to be only one of several causes for the dramatic decline in bee colonies, especially in Europe and the United States.
- Previous studies have found neonicotinoids can cause bees to become disorientated such that they cannot find their way back to the hive, and lower their resistance to disease.
- Recent experiments showed that the insecticides also diminish the viability of bee sperm.
- The European Union (EU) has placed a moratorium on the sale of neonicotinoids, though some European countries continue to use them under various exemptions.
Source: The Hindu
