Some relevant information:


>At the local level, a Fast Africanized Bee Identification System (FABIS)
>test can be performed. Starting with a sample of 50 to 100 bees, 10 bees
>are randomly sorted. The right wing is removed from each and mounted on
>microscope slides, and the average wing length is calculated. If the
>average wing length is over 9mm, the bees are European Honey Bees. If the
>average wing length is under 9mm, the bees are suspect Africanized Honey
>Bees. They are only suspect AHB because there are some Egyptian Honey Bees
>in the county that are a domesticated bee but are slightly smaller that
>the EHB. Some EHB are also slightly smaller than usual. The FABIS test is
>like the TB skin test. If the test is negative, you do not have TB. If the
>test is positive, you might have TB but need a more sophisticated test to
>be sure.
>
>If there is a need to know for certain that the sample is AHB or not,
>e.g., a multiple stinging incident or death, the sample is sent to the
>California Department of Food & Agriculture (CDFA) for further testing.
>They can perform either a DNA, or complete morphometrics test. The DNA
>test compares the DNA from the sample to known DNA standards to determine
>whether the bees are AHB or not. This test can be done on a small sample
>size but not if the bees were killed with certain pesticides. The
>chemicals used to kill the bees interfere with the test. Complete
>morphometrics can be used when the sample is contaminated with pesticides.
>Complete morphometrics is a series of very precise measurements of various
>parts of the bees in the sample. Some involve lengths of specific body
>parts, some involve the angles of wing veins. These measurements are then
>averaged and compared to a standard. A complete morphometrics test
>requires a larger sample size than the DNA test. Both tests are quite
>accurate and are considered the final word in AHB determination.

http://acwm.co.la.ca.us/scripts/AHB.htm#first

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Hybridization between European and Africanized honeybees in tropical
Yucatan, Mexico.
II. Morphometric, allozymic and mitochondrial DNA variability in feral colonies

excerpts:

>The feral colonies in this study showed evidence of much introgression of
>European genes, even 10 years after the first report of an Africanized
>feral colony in the Yucatan. In contrast, the first feral colonies
>collected from this region of Mexico in 1988 seemed to have practically no
>evidence of European gene introgression, but 5 years later and onwards the
>presence of European genes has been clear in feral bees.
>
>As the present data suggest, hybridization between Africanized/European
>colonies in the tropics can occur provided sufficient European colonies
>exist in an area to counterbalance the rapid population growth of
>Africanized colonies. A common scenario in South and Central American
>countries has been a complete and rapid elimination of managed European
>colonies with little introgression of European markers in the feral gene
>pool [7, 28]. South American countries had very small resident European
>populations compared with the large commercial populations found in SE Mexico.
>
>Recent studies also provide support for the hypothesis that variation in
>European gene introgression in feral populations has been due to numerical
>differences between managed European colonies and feral Africanized colonies.
>
>Probably a combination of all these factors has played a role in
>determining that 10 years after the arrival of Africanized honeybees in
>Yucatan, feral colonies in this area of Mexico still show evidence of
>mixed European/African composition, as indicated by morphological,
>isozymic and DNA markers. This evidence suggests that introgressive
>hybridization rather than complete replacement is the most parsimonious
>hypothesis to explain Africanization in Yucatan, most likely due to the
>presence of a large population of resident European bees.