JsHoney wrote: How do the experts tell AHB from other bees?
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.
Picture of a AHB