Neonicotinoid impacts on birds

The catastrophic impact of neonicotinoid pesticides on bees has long been suspected but now it's becoming clear that they are hitting farmland bird populations too.

Neonicotinoids are the most widely used insecticides in the world. They are toxic to most arthropods and they are widely applied as seed dressings because they act systemically, protecting all parts of the crop. Like so many pesticides used in the past they can persist and accumulate in soils and leach into waterways.

As a result of many studies, both in the laboratory and in the field, there is a widespread view among entomologists that neonicotinoid use has - in combination with the loss of flower-rich meadows, disease and mite infestations - contributed to the decline of bee populations. They are much less toxic to vertebrates and until recently evidence of any impacts on birds has been merely suggestive. However, a recent paper by Caspar Hallmann and his colleagues published in Nature has shown that decreases in bird numbers in the Netherlands shown by the Dutch Common Breeding Bird Monitoring Scheme have been most rapid in areas with highest environmental concentrations of neonics.

Read the paper here

Bees Losing Sense of Smell

It has been reported by neuroscientists at the University of Southampton that traffic fumes render the scent of flowers barely recognisable to honeybees and could have a serious impact on their ability to find food. The report states that reactive pollutants in diesel destroyed key chemicals in the odour of oilseed flowers making them smell different to the bees.

Honeybees have a sensitive sense of smell and an exceptional ability to learn and memorise new odours. The effect of diesel fumes on flower scent could have serious detrimental effects on the number of honeybee colonies and pollination activity.

Three quarters of the world's food crops rely on bees and other natural pollinators, a service valued at £135bn a year globally. But there have been serious declines in natural pollinators in recent decades. A combination of factors has been blamed including the huge loss of the flower-rich habitats that sustain bees as well as disease and the impact of agricultural insecticides. And now it appears that traffic fumes are adding to the problem.

Honeybees are very, very selective on what they home in on. They do not go randomly from flower to flower. The team of scientists found that it was the highly reactive nitrogen oxides (NOx) that chemically altered the smell by removing key chemicals within a minute of exposure in the laboratory environment.

Emissions from diesel regularly exceed the limits for nitrogen dioxide and emissions from petrol vehicles often contain even higher levels of NOx. These nanoparticle pollutants, already known to harm human health, may also be affecting bees.