Differences In Larval Mortality Research Articles

Selection for American Foulbrood Resistance in Larval Honey Bees1

Selection for resistance to Bacillus larvae White, the causative organism of American foulbrood, was attempted in young Apis mellifera L. larvae. The F1 generation of a cross between a susceptible (Van Scoy) and a resistant (Brown) line was used as the parent stock for this experiment. Female and male larvae were treated individually with 1000 spores, and survivors were selected as parents for the next generation. Five methods of selecting parent stock were used in 3 succeeding generations. The first generation of selection gave significant differences in larval mortality between mating types. Most progress was made with gamete selection. Similar responses occurred in generation 2 with a smaller increase in resistance in the selected classes. Progeny testing of the third generation occurred during a period of dearth. A gain in resistance was measured only in the selected gamete by selected zygote class. The 2 other selected classes had losses in resistance, but neither returned to the initial generation’s level.