Greetings, Andy, Les, Michael adn others on this thread.  I've been off in
the mountains for a few days and just discovered it.
 
Last year, while digging up everything I could find for a new chapter
about poisonous plants in the third edition of Honey Bee Pests, Predators
and diseases, (due out this winter according to Kim Flottum), I found some
information that may add to the discussion including Vansell (via Roy
Barker, previous author) who worked on California buckeye poisoning.
Please see below...
 
 
On Mon, 8 Sep 1997, Andy Nachbar wrote:
 
> At 11:18 AM 9/8/97 -0700, Bill Truesdell wrote:
> >Michael Reddell wrote:
> >>
> >> CALIFORNIA buckeye is the culprit.  The big "horse chestnut" trees that
> >> most people think of are different, and apparently not a problem.
> >
 
After California buckeye was implicated researchers in Europe wondered
whether the related horse chesnut, native there, would also be a
"culprit".  Maurizio 1945 and Velthoen 1947, found that pollen from horse
chestnut (Aesculus hippocastanum) and dwarf buckeye (A. parvia) was found
in bee guts from bee colonies showing symptoms of poisoning.  Feeding
bees with blossom extracts caused niticeable symptoms and reduced life
spans.  Saponins, a toxin have been found in sap, nectar and pollen of
horse chestnut. - This "may" be the toxin? I have found no other info
about this and more study is needed before we can say other buckeyes or
horse chestnut is "for sure" toxic to bees.
 
> >> The only solution I know of is to move the bees during buckeye bloom.
> >
> >Excellent advice. Can only add that ABCand XYZ of Beekeeping also
> >suggests feeding sugar syrup and bee collected pollen from other plants
> >when the buckeyes are in bloom to dilute the buckeye nectar and pollen-
> >if you cannot move the hive.
>
> Its the nectar of the California Buckeye that kills the bees.
 
Vansell 1926 - described buckeye poisoning as "The effects on bees of
buckeye honey, pollen, nectar and sap are sometimes very severe. Not only
the field bees, but the adult queen, and drones are affected as well as
the larvae and emerging young adults. In severe cases, the whole colony
dies with the hive full of honey. The majority of the larvae being fed are
killed outright and are, in the main, devoured by the adults..."
 
 When it is
> really bad, (when the trees are bothered by aphids and/or other pests), you
> can find dead bees on the ground under the trees, and on the blossoms
> themselves. The Buckeye bees hatch out with deformed wings in extreme cases
> after an initial kill of young bees that pile up in front of the hives. The
> bees will eat the hair off of the effected bees making them look shinny.
> The queens are also damaged and buckeye hives are hard to repair with added
> bees or brood, or a new queen as long as the nectar is in the hive.
> Preventing 100% of the pollen from entering the hive does not help and this
> pollen when fed to other bees does not seem to affect them.
>
> Feeding sugar syrup at the time of bloom does work
 
This was also recommended by Vansell and I feel it helps to dilute the
effects of the toxin.
It's the quantity of toxin - the dose - of any poison that is in my
opinion the key.  When bees have nothing else to forage on, due to adverse
weather, especially drought reduction of other food plants, the bees have
nothing else to forage on and ingest much more toxin.  If only a few
California buckeye trees are present and other food is available, then
symptoms may not be noticeable.  You may see nothing more than a few dead
larvae, pupae, being ejected from the hive.
 
mostly in the coastal
> areas as the trees seem to effect the bees less there and in some years on
> favored locations pure Buckeye Honey can be extracted. Its is white in
> color and granulates in the comb if left until the Sage flow. In the Sierra
> foothills the Buckeye seems to always be bad on the bees and moving away
> from it is the best plan.
 
I couldn't find any info about whether honey from buckeye is a problem for
people.
 
Vansell also recommended moving bees if they were in an area with much
buckeye.  He also said that queens became affected, becoming incapable of
laying fertile eggs until moved to another area.
 
At one time a old time bee breeder had a line of
> bees that were not affected by Buckeye. I don't know if anyone continues
> with them today, they were naturally dark gentle bees and very productive.
>
> California Buckeye trees are very hardy and hard to kill. Beekeepers and
> cattlemen have carried out several eradication attacks on them without much
> success in the past. The cattlemen were interested because of a condition
> they call "Buckeye calves", the cows abort late term or the calves are
> deformed because they are believed to have eaten from the fruit of the
> Buckeye tree.
>
> The California Buckeye tree makes a nice yard tree and if irrigated will
> keep its leaves longer then in the wild where they are dropped soon after
> blooming unless it is a very wet year or they are growing with their roots
> in water.
>
> ttul, the OLd Drone
>
 
Hope this info helps,  grins, John
 
John A. Skinner           218 Ellington Hall
Extension Apiculturist    University of Tennessee
[log in to unmask]          Knoxville, TN  37901   (423)974-7138