Parasitic Cape honey bee workers (Apis mellifera capensis) are not given differential treatment by African guards (A.m. scutellata)

Workers of the Cape honey bee Apis mellifera capensis started to parasitize the African honey bee A. in. scutellata after being introduced into Gauteng (former Northern Transvaal Province) from its native territory, the Cape Province. The A. m. capensis strain that is parasitic has at least two traits that make it a serious pest of the native African bee colonies: workers rapidly develop their ovaries when in a non-capensis colony even when a queen is present, and worker-laid eggs are not killed by worker policing. Here we investigate whether A. m. capensis workers also have special mechanisms to circumvent the guard bees of A. in. scutellata thereby aiding their horizontal transmission between infected and non-infected colonies. We studied the acceptance of non-nestmate A. m. capensis and A. m. scutellata bees by guards of African bee colonies by introducing them to the hive entrance of A. m. scutellata colonies. We used 2 A. m. scutellata discriminator colonies that were both split into a queenright and a queenless portion. Our results suggest that invading workers of A. m. capensis have no special mechanisms to circumvent the African guards. Neither race of the introduced bee nor presence or absence of the queen in the guarding colony affected the proportion of introduced workers accepted. When pooled, 15% of introduced A. m. capensis and 18% of A. m. scutellata non-nestmate workers were accepted by African guards.