Dorian Pritchard “Selective breeding without inbreeding; where’s the happy medium?”

Dorian Pritchard is a retired university lecturer in medical genetics. He has a PhD in genetics, is author of “Foundations of Developmental Genetics” and first author of “Medical Genetics At A Glance”. He has run 4 – 20 national hives in Northumberland since 1979 and was inspired to concentrate on the native Dark Bee, A. m. mellifera, after comparing the performance and honey quality of local and foreign bees side by side in a rape field. He has been prominent for many years at local, national and international levels of beekeeping, serving as Conservation Officer of BIBBA and for 10 years as President of SICAMM, the international association for conservation of the Dark Bee. He has taught some 300 beginners in his classes at Kirkley Hall Agricultural College. His publications in the beekeeping press reflect his deep concerns for native honey bee conservation and his success in selecting Varroa resistant, near-native bees.

Lecture Title: “Selective breeding without inbreeding; where’s the happy medium?”

Genetic improvement of bees is best achieved by the co-assembly of the favourable genetic attributes of related stocks into one or more superior lines. Breeding from the best can achieve this, but this strategy and the use of “multi-breeder queens” also accumulates recessive alleles, some of which are harmful. In the single-copy, “heterozygous” state recessives are unexpressed in females, but when “homozygous” (i.e. present as two identical copies), they can cause serious detriment. In honey bees a particular problem arises from homozygosity of alleles of the sex-determining gene, which causes fertilized eggs to develop as abnormal “diploid drones”. These are eliminated by the house bees soon after emergence, leaving empty wax cells within sheets of sealed worker brood, causing a constant drain on the productivity of the queen and serious colony under-performance. Inbreeding exacerbates reduction in the range of sex alleles and increase in the number of diploid drones; eventually colonies die and the population goes extinct. The frequency of empty brood cells can however be used to estimate the number of sex alleles in the population, predict its long term viability and assess the advisability of extending the genome by outbreeding.