I have received a few emails about imidacloprid over the past months and
have added a few items to the Imidacloprid site at
http://www.internode.net/honeybee/Imidacloprid/

The most recent item, received form a friend is not yet posted there and
since it is short, and the web links (below) to the source is not working
well.  I'll post it here:

http://chemecol.or/meetings/99/p-26.html
http://www.lnb.cnrs-mrs.fr/FRENCH/activ/ISCE?posters25-49/posters25-49.html

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(p-26)IMPAIRMENT OF OLFACTORY LEARNING PERFORMANCES OF HONEY BEE BY LONG
TERM INGESTION OF IMIDACLOPRID


Axel Decourtye, M. Le Metayer and Minh-ha Pham-Delegue


Laboratoire de Neurobiologie des Invertebres, INRA, Domaine de la
Guyonnerie, BP 23, 91440 Bures-sur-Yvette, France.


Two standardized bioassays to evaluate sublethal effects of pesticides on
The e behavior of Apis mellifera L. were used to test the insecticide
molecule: imidacloprid (chloronicotinyl). Methods used to study learning
processes and foraging behavior were adapted to test the sublethal effects
of imidacloprid at both the individual and colony levels under confined
conditions. At the individual level, we studied the effects of long term
ingestion of imidacloprid on olfactory learning performances using the
olfactory conditioning of proboscis extension on restrained bees. At the
colony level, a sugar solution containing 50 ppb of imidacloprid was fed to
a colony in a flight cage to determine the effects on flight activity as
measured with an activity counter set at the hive entrance and olfactory
discrimination performances on an artificial feeder. The olfactory
conditioning procedure applied to restrained individuals showed that honey
bees surviving the diet contaminated with 4 - 40 ppb of imidacloprid had
reduced olfactory learning performances. Only the concentration of 4 ppb
showed a percentage of mortality not significant different from the control
diet after long term ingestion. In the flight cage, administration of
imidacloprid induced a decrease in the flight activity and the olfactory
discrimination performances. Thus the decrease in the learning performances
induced by imidacloprid at the individual level was confirmed at the colony
level. However, it would be necessary to conduct further work on the
dose-response relations, and on the sublethal effects of different
pesticides, before concluding about the hazard of imidacloprid on honey
bees.

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Although I am slow updating the Imidacloprid site, I do appreciate any
contributions, and remind all that with all the SPAM, many of us delete a
lot of email without opening it.  If you send me something, please make sure
the subject line of the email is meaningful and also please follow up if you
do not hear back from me in a reasonable time.  I normally acknowledge
receipt of any email I read.

allen