On Fri, 31 Jan 1997 13:19:51 -0500, Excerpts from BEE-L wrote:
 
>Reply-to:      [log in to unmask]
>From:          David Eyre <[log in to unmask]>
>
>We have been working with Dr.Nasr and the Ontario Breeding program for
>a number of years now. They can tell us whether our strain of bees are
>resistant or tolerant to T-mites, but not a word about the mechanisms.
>It has been known, for a long time, that the mature mite moves out and
>looks for a new host under 4 days old. Beyond that, nothing.
>
>It is thought that the mites don't like the taste of the new host and
>move back out, as there is record of bite marks in some tracheae but
>no mites.
 
Round the half of this century tracheal mites were considered to be serious
pest in the Czech Republic (Central Europe), too. Strict veterinary
measures were undertaken when T-mites were find in some apiaries. 30 years
ago when I started keeping bees an evaporation of a fluid prepatation BEF
through winter was a common procedure to treat T-mites where it was
necessary. Recently bees are considered to be resistent against the pest.
Nothing is used and colonies survive and bring yields. I don't know it
exactly but  morphology and speed of hardenning of chitin hairs protecting
the first thoracial spiracles (openings leading into the tracheal trunc)
were considered to be involved here. According to this theory bees with
better protection of the spiracles can resist the invasion of mites.
Best regards,
Vladimir Ptacek
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Fac. Sci., Dept. Anim. Physiol.       E.mail: [log in to unmask]
Masaryk University                    phone:  .42/5/41129 562
611 37 Brno, Czech Republic           fax:    .42/5/41211 214