Morphometry

This page is credited in full to Dave Cushman who created it. His voice is expressed in black colour text and any additions or comments in blue belong to myself. Credit: Dave Cushman’s website.

PH.

 

Morphometry
Called Morphology in some parts of the world

However, morphometry is the precise study of anatomical characters by measurement and morphology is merely the study of form and structure.

The Racial types and strains of honey bees have distinctive body characteristics that can help to distinguish both type of bee and purity of breed. Of these two aspects the one of greatest importance is purity of strain or more precisely the degree of hybridisation (the lower the better). These methods are all of secondary importance to ‘colony assessment’ characteristics and should be used to refine partly selected strains rather than as a direct descriptor of race. There is no point in propagating ‘bad’ or undesirable behavioural traits regardless of how ‘pure’ the strain is.

Genotype and Phenotype are the two elements involved in this definition…

Phenotype… Is the observable physical description of the organism or parts of the organism at multiple levels… The whole creature, it’s external appearance and internal organs, the cells and tissues of those organs along with form and structure of these organs, the actions and metabolism of the organism as well as the behaviors exhibited. This is the data we record to ascertain race or strain, but we rely on behaviour first and use morphometric measurements as confimation of our recordings as well as for degree of purity of type and refining fine differences.

Genotype… This is the inheritable information, the genetic blueprint that the living organism was assembled into using information coded in genes. Genes are found within almost all cells in the form of DNA they are copied during cell division and thus passed down the generations (sometimes with mutations). DNA can be used to verify or check various features found during morphometric and behavoural analysis and can be used to track variations in a population over time or variations by region.

What characters we measure and why

General Appearance… a simple and obvious characteristic that most would agree on, but it is subjective in nature and you should be wary of ‘seeing what you desire to see’.

Body colour… is only important if describing a bee with a high degree of “purity of strain” {PAGE in preparation on colour, rings & spots}. Colour in itself is not a positive indicator, but can be used to rule out certain hybrids.

Rings and Spots… may help give additional information on the degree of hybridisation.

Drone body colour… is used as some strains exhibit differences between male and female colouration.

Queen Characteristics… (not listed in the table below, but may be included later or produced as a sub page). Things like leg colour and body colouration can be different from standard worker characteristics.

Worker Cellsize… Not normally included in previous lists of characteristics, but included here in the light of intended testing involving different cell sizings. (It is thought that there is a correlation between the size of the 3rd tergite and the size of cell the bee was bred in. (This needs further research and investigation and may or may not vary between races and strains.))

(Further information… ‘Cellsize’ ‘Cellsize Regression’ ‘Cell Size Test’. )

The following information concerning thorax size is from Dee Lusby in answer to the question
“So what is the size of the thorax of a bee raised in a 4.9 mm cell?”
The range observed for 4.9 mm foundation was:-
min 3.6 mm – Medium 3.7 mm – large 3.8 mm for the thorax, with the majority around 3.7 mm.
The range seen when 5.0 mm – 5.1 mm foundation was used:-
small 3.7 mm – Medium 3.8 mm – large 3.9 mm for the thorax, with most close to 3.8 mm.

Cubital Index… By measuring the ratio of two of the wing vein segments we obtain measurements that are consistent for given races of bee. (see… Wing Measurement.)

Fore wing Length… Measuring the length of the wing gives further information. (see… Wing Measurement.)

Discoidal Shift… Is a measure of shape within the cells of the wing venation. (see… Wing Measurement.)

5th Tergite Overhairs… is dealt with on a separate page along with tomentum width.

Tomentum Width (4th tergite)… the page Overhair Length & Tomentum Width deals with these items.

Worker hair colour… This character has more consistency as hybridisation decreases.

Drone hair colour… This character also has more consistency as hybridisation decreases.

Proboscis… I am not completely sure why this measurement is taken (I have not tried it yet myself).

Tongue… whilst this may be useful information I feel that too much emphasis is placed on the length of it and it can be a ‘red herring’, however there may be subtle changes due to village by village regions and changing forage.

Tongue Reach… Of all measurements to do with the tongue this is the only one that is significant with regard to nectar gathering, yet it rarely is recorded. (See Glossameter)

Data for other races

Peter Edwards has provided the following data for Apis Cerana…

On a visit to Kerala in January 2007, the Associate Professor of Beekeeping at Kerala Agricultural University, Trivandrum, Dr Stephen Devanesan was working on the morphometry of Cerana and asked if we could measure some wings for him. The results we obtained with CooRecorder and CBeeWing were:
47 wings:
Mean discoidal shift angle 4.0? Std deviation 1.8
Mean cubital index 2.92? Std deviation 0.46
These were lowland Cerana – more yellow – we have not tested the darker hill strains.

Other criteria can be used and indeed are used for particular fine detail within closely matched strains, including many wing vein points and various lengths of limb segments.

Sample Size…
Fifty bees per colony are recommended for wing venation studies unless you are already some way down your selection route. (As BIBBA is generally dealing with stock that has a ‘history’ they use thirty bees per colony.) The characteristics other than wing vein measurements only require a sample of ten. It is a basic trade off the larger the sample the greater the accuracy… But more work is entailed in gathering the information.

Tools for the tests…
Are available on the Morphometry Tools page. The types represented include:-
Glossimeter, tomenta hair eyeglass, Herold fan, discoidal card.

The Scattergram…
Is a useful tool for aggregating data as it gives an easily seen graphical representation of both the race of bee and the degree of hybridisation, it deserves a page to itself, but other items are included here simply because BIBBA have grouped them all together in the past. The page is rendered suitable for printing on an A4 page at a resolution of 800 x 600. The description of how to use it and interpretation of results is dealt with under the heading below (Statistical analysis).

Presentation of Morphometric Data This page gives some details of different ways of representing the data to give a graphic presentation that can readily be absorbed and remembered.

Statistical analysis…
This page also includes Jacob Kahn’s ideas on what to do with odd ‘fly away’ points.

Ruttner’s Multivariate analysis…
(future sub page) with extra info from DNA studies.
References…

Ruttner (1986) values in [] type brackets
Gilles Fert (ISBN 2 905851 1-2 1997)
After J. Fresnaye 1980, values in { } type brackets
BIBBA (various publications & leaflets)
Own conference & lecture notes (mainly BIBBA sources)
Eva Crane (Bees & Beekeeping) (various sections)
Breeding Better Bees, John Dews & Eric Milner
Olda Vancata via Email to BIBBA-L marked with “*”

Having done some hundreds if not thousands of wings I put this up, outmoded as it may be so that those with a beginning interest can at least try for themselves before getting into the far more expensive realms of DNA testing.

PH

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