As we have stated previously, wing length is not considered a reliable indicator in areas of hybridization; European bees average larger than Africans, when taken as a whole. For positive identification, PCR tests are considered state of the art. These tests are similar to so-called paternity tests or tests used to identify criminal suspects using crime scene DNA. No test is perfect, but these tests are extremely accurate.
In laymen's terms, what they do is extract the DNA from the bees' legs, and amplify one section that is a marker for European bees. A marker is simply a series of GATCs that has been found to be unique to the one and not present in the other. European bees have the marker, African bees don't. If you read through to the end, you will see that they use two markers in this case.
Here is an example of their use in studying mating frequency of African bees compared to Italian bees.
> Samples of feral honey bees were taken in remote regions located about 40 miles north east of the USDA Carl Hayden Bee Research Center in Tucson, Arizona, USA. These feral colonies were located in a desert study area that has been monitored since 1987 and has long been highly Africanized (Loper, 1997; Loper et al., 2006).
> In addition to the collected feral samples, several control samples were analyzed to ensure that the molecular techniques were accurate and robust. Firstly, samples were analyzed from instrumentally inseminated European honey bee queens (derived from A. m. ligustica) with known numbers of unrelated drones. Secondly, adult samples were tested from three managed European hives at the Carl Hayden apiary, which were headed by commercially produced (and therefore naturally open-mated) European queens (A. m. ligustica). Thirdly, adult samples were tested from four managed colonies headed by AHB queens that naturally mated in the Catalina Mountains of Pima County, Arizona. Africanization had previously been confirmed in these colonies using mitochondrial DNA and morphometric analyses
> Standard diagnostic tests were conducted on a subset of workers from each colony to determine if they were of African or European origin following the RFLP mitotyping procedure of Pinto et al. (2003). Briefly, for six individuals from each colony, a 485-bp section of the cytochrome b gene was amplified and subjected to a restriction enzyme digest using BglII. The products were then run on 1.5% agarose gels and visualized with ethidium bromide. Those samples with two products (291- and 194-bp) were considered to be of European maternal origin (E mitotype), and those uncut were considered to be of African maternal origin (A mitotype).
Mating frequencies of Africanized honey bees in the south western USA
Tarpy, et al. Journal of Apicultural Research and Bee World 49(4): 302-310 (2010)
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