13.2. Time and weather restrictions for studying mating behaviour
Reproduction in Apis only takes place during a season with ample nectar flow and high availability of pollen. Then the number of worker bees increases rapidly and the colonies soon become strong enough for fission. In addition, conditions for the survival of swarms are optimal. Shortly before swarming season, colonies start producing some thousands of drones and later they also produce about ten queens. These numbers and the number of swarms vary according to the strength of the colonies and depend on species and races. This dependency on season restricts the time for studying mating behaviour to a short period per year. In addition, the reproductive season cannot be pinpointed to fixed dates but varies according to climatic conditions in different years and geographical and environmental conditions.
Additional restrictions occur because of the short daily mating flight periods. In regions were several Apis species coexist like in South East Asia, a fixed daily mating flight period guarantees reproductive isolation (Koeniger and Wijayagunesekera, 1976; Koeniger and Koeniger, 2000; for review see Otis et al., 2001). In regions with several species, the daily period is about 90 minutes. In regions where only one species occurs, the mating flight period is extended to about 3 hours. The time of flight is genetically fixed in queens and drones and not regulated by the colony (Koeniger et al., 1994). Drone flight starts between 15 to 30 minutes before queens start and also end later (for review see Koeniger et al., 2011).
Generally, queens and drones fly at temperatures above 20 ºC, blue or partly clouded sky, and low wind velocity. But this behaviour is greatly influenced by the weather of the days before. When there was a rainy period of some days, queens and drones fly under suboptimal conditions and drones react to queen dummies more frequently than after a period of good weather conditions.
It is therefore advisable to observe the hive entrance of some bee hives and start observations and experiments on mating behaviour only when the exiting and returning of drones indicates full mating flight activity. This is important in particular when one wants to detect or work at DCAs.