-Until the late 1800s honeybees in Britain and Ireland were raised in brood cells of circa 5.0 mm width. By the 1920s this had increased to circa 5.5 mm. We undertook this study to find out if present-day honeybees could revert to the cell-size of the 1800s and to evaluate resulting changes in honeybee morphometry. Seven measurements were made; head width, radial cell length, trachea diameter, cubital index, discoidal shift, bee mass and abdominal markings. The study showed that the colonies of Apis mellifera mellifera bees had no apparent difficulty in drawing out the wax and raising brood in the reduced brood cells. Bees reared in these cells were significantly smaller, but this reduction was not in proportion (<20%) to the change in the brood-cell size in contrast to the strongly proportional relationship in other bee strains. Also the ratio of thorax width to cell width ('fill factor') was much larger in the Apis mellifera mellifera strain.Apis mellifera / morphometry / cell size / small cell / brood combs

-An assessment was made of tracheal mite susceptibility in honeybees pupated at a low temperature. Using a laboratory bioassay, an experiment was conducted to compare the performance of newly-emerged (callow) bees raised at 30 ºC with those raised at the more normal brood temperature of 34 ºC. The reduced temperature caused a delay of over 5 days in the emergence of the bees from the brood cells. The callow bees raised at 30 ºC had over twice the mite prevalence level. The fecundity of the mites in the tracheae was similar for both temperature conditions. Increased susceptibility to tracheal mites resulting from reduced brood temperature may help to explain the mortality, in the temperature-stressed late winter/early spring period, of colonies with a moderate mite infestation in autumn. Further work is required to identify the mechanism responsible for this increased susceptibility.Apis mellifera / Acarapis woodi / tracheal mite / brood temperature / susceptibility to infestation

The varroa mite (Varroa destructor) is an ectoparasite of the western honeybee Apis mellifera that reproduces in the brood cells. The mite will generally kill colonies unless treatment is given, and this almost universally involves the use of chemicals. This study was undertaken to examine the effect of small cell size on the reproductive success of the mite, as a method of non-chemical control in the Northern European honeybee Apis mellifera mellifera. Test colonies with alternating small and standard cell size brood combs were sampled over a three-month period and the population biology of the mites evaluated. To ensure high varroa infestation levels, all colonies were infested with mites from a host colony prior to commencement. A total of 2229 sealed cells were opened and the varroa mite families recorded. While small-sized cells were more likely to be infested than the standard cells, mite intensity and abundance were similar in both cell sizes. Consequently, there is no evidence that small-cell foundation would help to contain the growth of the mite population in honeybee colonies and hence its use as a control method would not be proposed. Apis mellifera / Varroa destructor / cell size / natural mite fall / prevalence

The tracheal mite has been associated with colony deaths worldwide since the mite was first discovered in 1919. Yet controversy about its role in honey bee colony mortality has existed since that time. Other pathogens such as bacteria and viruses have been suggested as the cause of colony deaths as well as degenerative changes in individual honey bees. Using data from published work we developed a qualitative mortality model to explain colony mortality due to tracheal mite infestation in the field. Our model suggests that colonies of tracheal-mite infested honey bees, with no other pathogens present, can die out in the late winter/early spring period due to their inability to thermoregulate. An accumulation of factors conspire to cause colony death including reduced brood/bee population, loose winter clusters, reduced flight muscle function and increasing mite infestation. In essence a cascade effect results in the colony losing its cohesion and leading to its ultimate collapse.

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