Abstract:
It was determined that 300 Cape workers, Apis mellifera capensis (collected from each of
6 colonies at each of 5 localities about 200 km apart along an 800 km transect in the Western and Eastern
Cape Provinces, South Africa) was the sample size required to statistically estimate the proportions of
workers with spermathecae at each location at 95% confidence levels. Because of the extremely clinal nature
of this honeybee population, we tested the hypotheses that (1) ovarian number and development of the
spermatheca covary in Cape workers, and (2) covary clinally as well. A regression analysis revealed that the
frequencies of bees with spermathecae significantly decreased from west to east, with Stellenbosch having
the highest and Grahamstown the lowest frequencies. Spermatheca size also significantly decreased from
west to east. A multiple regression analysis revealed that the number of ovarioles significantly decreased
from west to east and also differed significantly between workers with and without a spermatheca. Moreover,
the number of ovarioles was significantly correlated with the size of the spermatheca and workers
without it had significantly fewer ovarioles. Both hypotheses are confirmed. The outcomes of these measurements
will provide a more quantitative basis for estimates of effective social parasitism among these
bees along a geographic continuum.
