[Pollinator] Fw: Natural pesticide impairs bumble bee foraging ability

[Peter Kevan]

> For your information:
>
> Natural pesticide impairs bumble bee foraging ability
> May 6, 2005
> Society of Chemical Industry
>
> Pesticide levels previously thought to be safe for pollinators may prove
> harmful to wild bee health, according to research published in Pest
> Management Science this month.
> The Canadian study shows that adult bumble bees exposed to the pesticide
> spinosad during larval development at levels they could encounter in the
> environment have impaired foraging ability.
> Bees are important pollinators of crops. In developed countries,
> approximately a third of human food is reliant on pollinating activity.
> Wild bees are thought to contribute significantly to this quantity.
> But although many pesticides are known to be toxic to bees, toxicity
> testing is largely restricted to direct lethal effects on adult honey 
> bees,
> if tested on bees at all.
> The researchers say sub-lethal effects on honey bees could be going
> unnoticed, and that different bee species could be also be affected.
> Lora Morandin and colleagues at Canada's Simon Fraser University tested 
> the
> effects of different levels of spinosad on bumble bee colony health and
> foraging ability.
> Spinosad is a natural pesticide derived from the bacteria Actinomycetes. 
> It
> is used in over 30 countries including North America, Canada and the UK to
> combat common crop pests such as caterpillars and thrips.
> Bee colonies were fed the pesticide in a manner that mimicked contact in 
> an
> agricultural setting. Adult bees and developing larva were exposed to
> spinosad in pollen.
> The bees' foraging ability on an array of 'complex' artificial flowers 
> made
> of centrifuge tubes was then evaluated.
> High levels of spinosad residues (about 10 times what bees should
> experience in the environment) caused rapid colony death. Colonies exposed
> to more realistic levels of spinosad in pollen did not show any lethal
> effects and only minimal immediate colony health effects.
> However, bees that were fed realistic levels of spinosad during larval
> development were slower foragers.
> They took longer to access complex flowers, resulting in longer handling
> times and lower foraging rates. The bees also displayed "trembling", which
> impaired their ability to land on the flowers and enter the flower tubes.
> This impaired foraging ability in bumble bees could result in weaker
> colonies and lower pollination of crop plants, according to Morandin.
> "Adult bees that have been exposed to a pesticide during larval 
> development
> may display symptoms of poisoning that are not detected with current tests
> required by regulatory agencies," she says.
> "In order to ensure sustainable food production, agricultural pesticides
> need to be safe for wild pollinators."
> The authors conclude that testing of new pesticides should include
>>examination of lethal and sub-lethal effects on wild bees.
> "Testing new pesticides on some species of wild bees will aid in 
> developing
> pesticides and use recommendations that minimize impact on wild bees,
> leading to healthier populations of bees and potentially better crop
> yields," says Morandin.
>
> (See attached file: Effect of spinosad on bumblebees.pdf)
>
>


--------------------------------------------------------------------------------


> Heather Clay
> National Coordinator
> Canadian Honey Council
> Suite 236, 234-5149 Country Hills Blvd NW
> Calgary AB  T3A 5K8
> ph. 403-208-7141
> fax 403-547-4317
> email: hclay at honeycouncil.ca
> www.honeycouncil.ca 
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