The idea that natural products are non toxic is simply wrong.  The most toxic chemical known is made by bacteria.  Many of the odor and color compounds made by plants are toxic.  For example, here is an article:

http://repository.ias.ac.in/68221/1/68221.pdf

Insecticidal Properties and Chemical Constitution
Flavanones and Chalkones

This paper used fish as an insect surrogate and shows many of the chemicals in the flavanone and chalkone classes are highly toxic to fish.

Here is another:

http://www.ncbi.nlm.nih.gov/pubmed/18095581

[Potential toxicities of flavonoids].
[Article in Chinese]
Wang H1, Zhao X, Wang Y, Yin S.
Author information
Abstract
Flavonoids may be natural components came from many vegetables and fruits. A variety of heath effects of these compounds were found. However, a few safety studies indicated that certain adverse effects of these compounds could influence on human health, which could involve genotoxic/carcinogenic effects or interaction with thyroid hormone biosynthesis. Isoflavones' estrogenic activity could influence on sexual development of young animals and children. Furthermore, flavonoids could inhibit the absorption of some nutrients, interact with certain drug pharmacokinetics and affect neurobehavioral development. In this paper, the potential toxicities of flavonoids from recently published papers were reviewed.

The above was translated from a Chinese language paper so the English is a bit strange I know.  The translator was Chinese it seems.

Many compounds which higher animals tolerate quite well are significantly toxic to bacteria or insects.  So, even if there is evidence of benefit or at least no significant harm in human diets this does not mean it will be safe to honey bees.  Antibiotics are good examples of chemicals highly toxic to bacteria but far safer to mammals while most insecticides (both synthetic and naturally occurring) are examples of chemicals very toxic to insects but often far less toxic to humans.  I recently read some stuff about eating flowers.  It turns out there are lots of flowers that are highly toxic to humans, including flowers that honey bees work for nectar.  The book I read on this topic stated that unless you knew a flower was safe to eat do not eat it as most are not safe.  Bees have to have a robust detoxification system to deal with such toxic materials.

Dick

" Any discovery made by the human mind can be explained in its essentials to the curious learner."  Professor Benjamin Schumacher talking about teaching quantum mechanics to non scientists.   "For every complex problem there is a solution which is simple, neat and wrong."  H. L. Mencken

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