Mark, thanks for your input and you have made some good points from the chemist's perspective.

When we (physiologists and physicians) want to dose an animal (or human) with a lipid-soluble chemical, we often don't take the oral route.  Instead, we apply the compound directly to the skin, diluted in some sort of vehicle.  For instance, steroids are frequently administered this way as creams.

My point is that cell membranes are lipid and they have high affinity for lipid-soluble substances.  Skin is largely cell membranes (the keratinocytes have dehydrated) and it takes up lipids very readily.  Once past the cell membrane, there are lots of lipid transport proteins in the cytosol to do the rest.  It's quite effective.

So I can very easily believe that larval cells take up substances from the wax they are adjacent to.  Their bodies don't have that protective waxy coat that the adults have, but their cells have lipid membranes like those of all eukaryotes.

It would be interesting to know what the rate of uptake is.  As you point out, it won't be simple diffusion, but it is diffusion nonetheless...and that was what I was asking.  Can Dick calculate it?

As far as "how long bees live", there is much literature that I don't have time to dig up right now showing that a) individual bees aren't living as long as they should/used to; and b) individual colonies don't live as long as they used to (with or without frequent requeening).  This is attributable to many factors as we all know.  Chemicals are not at the top of the list.  But the point is chemicals are one of the straws on the "camel's back".

Christina

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