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 exclus ively of hybrid workers did not differ in their response from ''pure'' Africanized colonies, suggesting that the strong defensive behavior o f Africanized workers is genetically dominant. European workers became more defensive in colonies that also contained hybrid workers, wherea s hybrid workers became less defensive in the same mixed colonies. In mixed colonies hybrid workers were individually more likely than Europ eans to sting a leather target but not more likely to guard the entran ce.