Bradford Urban Wildlife Group
Bradford Urban Wildlife Group
recording, observing and protecting Bradford wildlife & habitats
Neonicotinoids - Background
Neonicotinoids (NNC) are a group of pesticides related to nicotine. They are taken up by plants and poison sap-sucking insects.
The range of application methods, and the high rates of pest control mean NNC are the most used insecticides in the world, especially in North America.
Some pesticide is present in nectar posing a theoretical risk to pollinators.
In 2013 the European Union banned use of NNC after seeing studies linking neonicotinoids with honeybee colony collapse.
DEFRA advice in 2013 was that there was no proven link with harm to bees, but this conclusion was reached because laboratory research gave higher doses of NNC than would be found in the field.
Since the advice came further trials in semi-natural or natural settings have been carried out. Reports suggest that non-lethal doses of NNC cause ineffectual navigation and foraging in honeybees.
In combination with other risks this weakens the hive and may contribute to colony collapse.
More on neonicotinoids
Seed coating with a neonicotinoid insecticide negatively affects wild bees
Nature 7-5-2015, 521,77–80
Abstract
The key question is how neonicotinoids influence bees, and wild bees in particular, in real-world agricultural landscapes.
this study shows a commonly used insecticide seed coating in a flowering crop can have serious consequences for wild bees.
In a study with replicated and matched landscapes, we found that seed coating with Elado, an insecticide containing a combination of the neonicotinoid clothianidin and the non-systemic pyrethroid β-cyfluthrin, applied to oilseed rape seeds, reduced wild bee density, solitary bee nesting, and bumblebee colony growth and reproduction under field conditions.
Hence, such insecticidal use can pose a substantial risk to wild bees in agricultural landscapes, and the contribution of pesticides to the global decline of wild bees may have been underestimated. The lack of a significant response in honeybee colonies suggests that reported pesticide effects on honeybees cannot always be extrapolated to wild bees.
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Field realistic doses of pesticide imidacloprid reduce bumblebee pollen foraging efficiency
Ecotoxicology April 2014, Vol. 23, 317-323
Abstract
Bumblebees and other pollinators provide a vital service for agriculture. Recent studies suggest exposure to systemic neonicotinoid insecticides in flowering crops has sub-lethal effects on bumblebees resulting in reducing queen production.
The mechanism behind reduced nest performance remains unclear. Here Radio Frequency Identification (RFID) technology was used to test whether exposure to a low, field realistic dose (0.7 ppb in sugar water and 6 ppb in pollen) of the neonicotinoid imidacloprid, reduces worker foraging efficiency.
Whilst the nectar foraging efficiency of bees treated with imidacloprid was not significantly different than that of control bees, treated bees brought back pollen less often than control bees (40 % of trips vs 63 % trips, respectively) and, where pollen was collected, treated bees brought back 31 % less pollen per hour than controls.
This study demonstrates that field-realistic doses of these pesticides substantially impacts on foraging ability of bumblebee workers when collecting pollen, and suggests that this provides a causal mechanism behind reduced queen production after imidacloprid use.