Production of reproductives in the honey bee species Apis cerana in northern Vietnam

In 20 colonies of Apis cerana in northern Vietnam, colony growth, production of drones and queens (sexuals), and swarming and supersedure were related to available flower forage and climate. Despite the tropical setting of the study with year-round forage, production of sexuals was restricted to two periods from March to July and from September to December. Most swarming occurred in May when forage was most abundant. Positive correlations between available forage, colony growth, and production of sexuals suggest that the synchronized production of drones and queens is defined by nutrient flow into the colony. If flow is high, the colony starts growing; when the colony is large enough drones and queens are produced, and eventually the colony swarms. Production of sexuals is synchronized because foraging conditions are sufficient to allow growth for only part of the year. Patterns in drone and queen rearing by A. cerana are similar to patterns found in Apis mellifera. Variation may reflect differences in environment and between species..