Estimation of the Number of Lethal Alleles in a Panmitic Population of Apis Mellifera L.

EEKEEPERS have long been familiar with a poor type of brood which due to its €5 scattered appearance is sometimes called “shot brood”. An explanation for this character was given by MACKENSEN (1951). MACKENSEN inseminated several queens with semen of their brothers, and by brood viability studies obtained a 1: 1 ratio between high (close to 100%) and low (close to 50%) viable brood. He suggested that a series of haploviable homozygous lethals exists so that all females are s1s2, SZs3, s3s4, etc. . . . and the males sl, s2, sa, . . . sn. Any female sls2 mated with sa males would produce highly viable brood and any sls2 female mated either to s1 or s2 males would produce brood of 50% mortality. MACKENSEN suggested further that the inviable combinations ( ~ 1 ~ 1 , s2s2, etc.) could be males and, if so, the sex determination mechanism in Apis mellijerera L. would be the same as the one in Habrobracon except that the alleles are apparently completely lethal when homozygous. This last point of view, that homozygotes may be males, is a question of fact and acceptance of it must await proof that the homozygous dying larvae are male ones. Regardless of whether the series are sex alleles or whether they are only lethal alleles this discovery is outstanding. A queen showing a low degree of brood viability builds such small populations that the colony produces a small amount of honey; and the queen is likely to be superseded, which also lowers the yield. The studies herewith presented have the scope of estimating the number of these haploviable homozygous lethals in a random mating population of Apis mellqeru I,. so that a better understanding of the population genetics of these bees can be attained.