Mike and I were discussing his claim re large mite families. You say I should do my homework on it, I have indeed done my homework on it, it's something I've been looking into for a while now. Which is how I know he is mistaken.
Mike said- "One of the 'hygienic' mechanisms that seems most useful is that of 'uncapping'. Here bees detect mites in the capped cells, uncap and remove them. The more interesting part is this: they only detect those mites that have large families". (highlighting mine)
I said I think the statement is not correct, I was specifically referring to the part I have highlighted. I asked for evidence to back the statement.
Mike didn't think he needed to supply evidence[
I think what I said was some thing along the lines of, since you can't be civil, find it yourself. Anyway, some links and further reading with insights below. Note the quote from the 3rd link, which I think substantiates my claim.
(Search was: "bees uncapping, hygiene")
http://www.apidologie.org/articles/...7/Apidologie_0044-8435_1998_29_3_ART0007.html
http://www.glenn-apiaries.com/genetic_aspects_queen_production_3.html
http://www.extension.org/pages/30361/varroa-sensitive-hygiene-and-mite-reproduction
"We have observed that VSH bees respond vigorously to highly infested brood (e.g. 15–25 mites per 100 capped cells) that is transferred into the colony (Fig. 4). They uncap and remove many mite-infested pupae quickly. They respond with much less intensity to brood with low infestation rates (1–5 mites per 100 capped cells), probably because the chemical signals that trigger removal are less concentrated and harder to detect."
Now, before anyone starts throwing tantrums, the bit about 'bees effectively breeding less fecund mites' was my own interpretation of what is going on. I don't know if this has occurred to anyone else, but seems obvious to me that given that they are selecting highly reproductive mites for removal and letting less fecund mites go, that will be the effect. If you don't have a breeder-brain maybe its not obvious. Take it or leave it, for sure someone will poke fun at it.
Link on to selecting for VSH here:
http://www.extension.org/pages/30984/selecting-for-varroa-sensitive-hygiene
Good overview of US breeding programs, 2010
http://www.altigoo.com/IMG/pdf/Rinderer--Breeding_for_Resistance_to_Varroa_Destructor.pdf
This covers some distinct points:
Host adaptations reduce the reproductive success of Varroa
destructor in two distinct European honey bee populations
Barbara Locke1, Yves Le Conte2, Didier Crauser2 & Ingemar Fries1
http://onlinelibrary.wiley.com/doi/10.1002/ece3.248/full
"In Avignon, France and in Gotland, Sweden, Varroa miteresistant
honey bee colonies reduce the average reproductive
success of their infesting mites by about 30% compared to local
control colonies. Although these resistant populations are
genetically unrelated and separated by over 2000 km, natural
selection has in both cases resulted in the reduce reproductive
success of this parasitic mite.
From an evolutionary perspective, the Varroa mite’s strict
dependence on its host’s biology causing a reduction in host
fitness from parasitic infestation has imposed strong selective
pressures leading to a coevolutionary arms race. In most
cases of coevolution, parasites will have an evolutionary advantage
above their host due to their faster evolution caused
by a shorter generation time (Hafner et al. 1994; Schmid-
Hempel 2010).However, in this particular system, V. destructor
is of clonal origin in Europe with low genetic variation
(Solignac et al. 2005). In addition, the honey bee has 10 times
higher genetic recombination levels than any higher order eukaryote
analyzed thus far (Beye et al. 2006). These aspects
may have provided the honey bee with an evolutionary advantage
in the arms race with V. destructor, an arms race that possibly is in the hosts favor, with mite adaptations limited.
A counter-adaptation could be expected according to coevolution
theory (Thompson 1994; Schmid-Hempel 2010)
but with the lack of genetic diversity among mites this may
take a long time. On the other hand, the adapted resistance in
these two honey bee populations has evolved incredible fast
by natural selection.
Mechanistic explanations of the bees’ ability to suppress
mite reproductive success remain unknown. Both the
Avignon and Gotland populations have experienced similar
selection pressures of natural mite infestation that is unique
compared to most other European honey bee populations
due to apicultural management and both have evolved a similar
colony-level mite-resistant trait. However, these populations
have different life-history traits and different environmental
factors that would also be involved in their adaptive
responses to the mite pressure. The evolved mechanisms behind
the ability to suppress reproductive success of mites
may differ between these two distinct populations. In general,
one may expect different traits to be favored in different
populations living in distinct environments even with similar
natural selection pressures, especially in traits involved
in coevolutionary relationships (Thompson 1999). Although
the two populations have clearly both evolved the ability to
reduce mite reproductive success, the between-population
differences are less clear. Therefore, more detailed investigations
are necessary to identify and tease apart the possible
mechanistic differences.
A suggested mechanism involved in reducing the mite’s
reproductive success could be for example, the adult bee
behavior known as Varroa-sensitive hygiene (VSH), which
involves the uncapping or removal of mite-infested brood
(Harbo and Harris 2005; Ibrahim and Spivak 2006). It has
been shown that bee colonies expressing this behavioral trait
may selectively remove pupae with reproducing mites resulting
in the remaining infested cells having a misrepresented
higher proportion of infertilemites (Harbo and Harris 2005;
Ibrahim and Spivak 2006). This could potentially be a mechanism
of the Avignon population, in light of the observed high
mite infertility rates. Since the Gotland population does not
demonstrate hygienic behavior (Locke and Fries 2011) nor
had significantly high proportions of infertile mites, there is
no reason to suspect that they are expressing VSH. Instead,
the suppression of mite reproductive success in Gotland may
be due to another mechanism, such as pupal volatile compounds
that can inhibit the initiation of egg-laying of mites
(Garrido and Rosenkranz 2003; Milani et al. 2004).
Besides suppressing mite reproduction, both Varroaresistant
European honey bee populations in this study also
share the fact that they have been unmanaged, enabling natural
selection (as opposed to artificial) to shape the evolution
of their mite resistance. This is an important consideration
since it highlights the impact that apicultural practices otherwise have on these host–parasite interactions (Fries and
Camazine 2001), suggesting a human interference in coevolution
between species."
I will still be happy to discuss.
I'll believe that when I see it.
Mike (UK)