Diallel crosses of honeybees. 1. A genetic analysis of honey production using a fixed effects model
B. P. Oldroyd*, C. Moran And F. W. Nicholas
A partial diallel cross was formed between nine inbred lines of honeybees, using instrumental insemination. The queens were established in 4-frame nuclei and then transferred into 10-frame hive bodies. Colony weight gains were determined weekly during honey flows at several different sites. Combining ability analysis revealed significant differences between the lines studied. Large average heterosis effects were detected, but substantial specific heterosis was limited to only a few crosses. There were no significant differences between the performances of colonies of intra- and inter-racial hybrids, although all hybrids were superior to their inbred parentals. Short-term weight gains were phenotypically correlated with long-term weight gains. Where environmental conditions were good for honeybees, the genotype by environment interaction was small. Where genotypes were compared under both good and poor environments, the genotype by environment interaction was substantial. It is concluded that recurrent selection in the population that would be formed if the lines were pooled, would improve colony weight gain. Crossing of lines produced substantial worker heterosis in certain rare combinations. Selection on short-term weight gain should be adequate in improving colony honey yield, providing that the observed phenotypic correlations between short- and long-term weight gain have a genetic basis.