Genetic dominance and worker interactions affect honeybee colony defense

Colonies of honeybees (Apis mellifera L.) were established that varied in the proportions of their workers that were of European and hybrid (Africanized x European) descent. Colony defensive responses increased with higher proportions of hybrid workers. Colonies consisting exclusively of hybrid workers did not differ in their response from "pure" Africanized colonies, suggesting that the strong defensive behavior of Africanized workers is genetically dominant. European workers became more defensive in colonies that also contained hybrid workers, whereas hybrid workers became less defensive in the same mixed colonies. In mixed colonies hybrid workers were individually more likely than Europeans to sting a leather target but not more likely to guard the entrance.