Hi all
I posted about this somewhat hesitantly since I have been an old comb adherent for decades. Comb in my hives is easily 10-15 years old or more. My winter mortality has been steadily declining as I have gotten more aggressive on mite control.
Anyway, Hepburn & al state:
Comb waxes mediate several kinds of behaviours as well (Free 1987).
For example, Fergusson and Free (1981) found that the odour of comb alone was a
sufficient stimulus for worker bees to release scent from the Nasanov gland, a source
of a cluster-inducing pheromone (Free 1987). This is consistent with the fact that
honeybees prefer old combs to new ones, possibly because they have been doped
with footprint pheromones (Free 1987). Comb volatiles also stimulate increased
foraging (Rinderer and Hagstad 1984); Free and Williams (1972) discovered that old
combs were more attractive storage depots than new ones.
* negative aspects, in terms of health and production:
Dizaji et al. (2008) found that the age of honeycomb wax affects honey production.
A two year dataset (2005–2006) showed significant differences in honey
production, with higher yields produced in new combs and less in older ones.
Piccirillo and de Jong (2004) suggest that although honeybees are
attracted by pheromones in old combs, given a choice they will use newer ones.
Old combs can harbour pathogenic microbes, unhealthy antigens and other biological
hazards which have detrimental effects on honeybees.
* positive aspects, in terms of strength and insulation
Zhang et al. (2010) examined the effect of the viscoelastic nature of new
beeswax on the stress and strain fields in the wall of new comb.
[They found] a temperature increase inside the combs from 25 to 45 C would
result in the collapse of fully laden new combs. That this does not actually happen
is because the comb walls are continuously reinforced by silk cocoons during use
(Hepburn and Kurstjens 1988). Old comb walls that contain 34 % silk cocoons by
mass are practically insensitive to temperature fluctuations (Hepburn and Kurstjens
1988). The finite element calculations of Zhang et al. (2010) show that even if
there is some decrease in the shear modulus and strain of older combs with
increasing temperature, they will still have a sufficient margin of safety against
collapse, in an engineering sense.
Based on their results, Buchwald et al. (2006) showed that the combs of
A. dorsata, the giant honeybees, which build single but very large combs, are
indeed the stiffest and most resilient of all combs among the honeybee species.
They must also sustain the weight of the honey stores and brood nest (~45 kg),
and because the position of their nests are often on branches high up in trees, they
are also exposed to possible wind damage.
At the end of the day, it must be remembered that mature combs
are not exclusively made of beeswax. The combs of all honeybee species are fibre
reinforced, with increasingly more silk deposited with each successive generation
of brood (Hepburn and Kurstjens 1988)
Hepburn, H. R., Pirk, C. W. W., & Duangphakdee, O. (2016). HONEYBEE NESTS. Springer-Verlag Berlin An.
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