From: Erik Osterlund <honeybee@elgon.se>
Date: Fri, 4 Jan 2002 11:17:58 +0100
To: BiologicalBeekeeping@yahoogroups.com
Subject: Re: Brood diseases

At 07.22 +1000 02-01-04, T & M Weatherhead wrote:

> I know that David de Jong
>has done a lot of work with African bees as I have spoken to him on several
>occasions on queen breeding work reported out of South Africa but that was
>not on AM but African bees so it could not be applied to AM. What did he
>say was the difference in attraction? Did the varroa discrimimate on cell
>size thus inferring that varroa are able to measure the cell size somehow?

deJong said this in South AFrica, but the paper I was remembering was
published in Apidologie 1995 by Message and Goncalves. Both AFrican and
European bees are Apis mellifera. Don't know any scientist that says
general findings found on any AM don't apply to another type of AM, but
that's maybe something to think about, not only concerning African or
European or also concerning strains, also concerning varroa...
Anyhow the paper dealt with an Africanized queen and an Italian queen
heading the two colonies compared, but both were mated AHB. Pieces of combs
were inserted in both colonies which were naturally built by AHB and
Italian bees respectively. Interestingly is too that the smaller size was
4.5-4.6 (maybe without cellwall included, but that wouldn't contribute much
though) and the bigger was 4.9-5.1 mm. Now it would really have been
interesting to compare also 5.4-5.7 when already in this smaller range as
it really was, this result was obtained. The "large" cells here contributed
2.6 fold more to the reproduction of the varroa mite than the smaller
cells. The weight of the worker brood was also significantly higher in the
bigger cells than in the smaller, indicating differential feeding
(conclusion by the authors). Different causes for the higher number of
mites in the bigger cells were discussed, one discussed was the
differential feeding, in physical terms by the nurse bees, probably they
meant less number of visits. This would indicate a higher preference then
for drone brood in colonies with smaller cells when drood brood is
available. Another cause discussed was chemicals, for example an ester
(methyl palmitate) which had shown to be an attractent to varroa, isolated
from drone brood but also present in smaller amount in worker brood (Le
Conte et al 1989). So other attractants than juvenile hormon do exist. The
conclusion was that smaller cell size affects infestation and reproduction
of varroa. Now it had been really interesting to see a similar experiment
done with the large cells put to 5.4-5.7 and with other strains too. Why
has no one done that?

Trevor again:

>But this then leads to the conclusion that the smaller cell larvae is unfeed
>because of the lack of food and thus is not as well nourished as the larger
>celled larvae. This it makes it prone to more diseases as it is under
>nourished if we follow the conclusions recently published on this group.

Well, that has to be found out, hasn't it. Nature seems to advocate smaller
cell size than commonly used in our foundation. And there has to be some
cause for that. Nature only goes for survival and reproduction, so I doubt
smaller cell size gives bees more prone to diseases.

Best regards

Erik