http://www.exmoorbeesandbeehives.co.uk/ Buckfast UK.
My papas must be hot because by the 3rd generation I have some real HOT workers.... DCA has some africans hanging out, I buy mated queens.
Stuck in Texas. Learning Permaculture in drought, guess I will teach permaculture in drought. The bees are still alive.
Drone Congregation AreasBy: Clarence Collison
Queen producers need to know all about these.
September 01, 2008
Mating during the queen’s nuptial flight takes place in drone congregation areas (DCA), where many drones from nearby colonies gather. On warm sunny afternoons, sexually mature drones flock to these aerial zones. When a queen approaches a congregation area, drones chase her, forming a comet-like swarm in her wake. Several drones copulate with the queen in midair (Gries and Koeniger 1996), and then die immediately. The DCA’s persist from year to year whether or not a queen is present. It is still unclear why drones choose particular areas in which to congregate and how queens locate these areas, although DCA’s and the mating behaviors of queens and drones have been extensively studied.
Drones take their first flights between five and eight days post-emergence (Ruttner 1966). These first flights are short, possibly for orientation, and are followed by longer potential mating flights approximately 10 days later which can last more than 30 minutes (Witherell 1971). Drone flights take place in the afternoon, generally beginning about one hour before virgin queens take their nuptial flights (Ruttner 1966). When atmospheric conditions are favorable during the late Spring and Summer, drones can make several trips to the local DCA’s in a given afternoon. When drones reach the congregation areas, they remain flying in wide loops until their depleted energy stores bid them return to the colony to feed. Congregation zones have highly variable areas of 30-200 m wide by 15-40 m above ground. Several thousand drones participate in the congregation, which is formed irrespective of the presence of a queen (Ruttner 1966). A congregation is limited to its spatial parameters, and drones are not attracted by a queen flying outside the area (Ruttner and Ruttner 1965a, 1966).
The distribution of DCA’s has been studied using balloons carrying tethered or caged queens and by radar (Gary 1963, Loper et al. 1987). Such studies have shown that several drone congregation areas can be found within the flight range of an apiary (Zmarlicki and Morse 1963, Ruttner and Ruttner 1966). Interestingly, the location of DCA’s remains consistent for several years, which indicates that the DCA’s location has an attraction that transcends generations. The orientation mechanism that drones and queens use to find the congregation areas is not well understood, although it is believed that light distribution and the contour of the horizon have some influence (Pechhacker 1994).
Zmarlicki and Morse (1963) found that DCA’s were located within an open location for at least a hectare (2.47 acres) and were protected from strong winds. It appeared that the absence of obstructions such as high trees and buildings made a site more appealing to drones, but not all open, well-protected areas were congregation areas. The study of DCA’s is difficult because drones occupy a lot of air space, flying well above the ground. Although it is generally assumed that numerous colonies delegate drones to these congregations, experimental data on the number of colonies and the relative drone contribution of each participating colony have seldom been determined. The composition of drone congregations has important consequences for the genetic structure of honey bee colonies. The number of colonies represented in a congregation influences the relatedness between a queen and her mates, hence the amount of inbreeding and the overall genetic diversity in a single colony are determined at the congregation zones.
Modern technology has revealed the dynamic nature of the drone’s flight pattern between drone congregation areas. Using X-band radar, which tracks large groups of flying drones, scientists have found drone flyways that connect nearby DCA’s. The drone’s flyways form along prominent features of the land (tree lines, etc.). The DCA’s tend to form where the drone flyways branch. Presumably the drones are accumulating in the congregation areas as they re-orient and select their next flight direction. It is possible that mating could also occur in the flyways, but the flight pattern of virgin queens in this system of drone flyways is still unknown (Loper et al. 1992). An X-band radar unit was used to document honey bee drone flyways and DCA’s in a nearly flat desert area (Loper et al. 1992). Within an area measuring 5.0 x 2.0 km (km = .62 mi), adjacent to a commercial apiary, 18 km of flyways and at least 26 DCA’s were identified. These studies were conducted during March and April for four years (1987-1990), and they confirmed that the location of flyways and DCA’s were re-established day after day, year after year. Based on film records of radar images, researchers defined a DCA as a site approximately 100 m (1 m = 39.37 inches) in diameter where drones fly higher and are more numerous than in surrounding flyways. Flyways formed alongside the most prominent physical features – e.g. tree lines formed in washes – but these flyways also branched, particularly when additional tree lines became visible on the near horizon. Most DCA’s occurred at these branch points; thus the accumulation of drones at a DCA may result from rapid turning and altitude changes as the drones re-orient and select their next flight direction. The maximum height of drones in flyways was 21 m, whereas in DCA’s drones were 30-50 m above ground. Flyways are more prevalent than DCA’s and contain large numbers of drones, so it is possible that virgin queens flying upwind or alongside flyways may be mated en route to the DCA.
Selected drone congregation areas were regularly observed for five years to verify that the dimensions of these congregation zones did not change greatly during this time (Ruttner and Ruttner 1968). When strange colonies were introduced into the vicinity, new drones were found at the congregation areas on the first day in equal proportion with local drones. This was true for congregation zones both near and distant to the apiary (2-3 km). Drones of different races of Apis mellifera (carnica, ligustica, mellifera, intermissa) were found at congregation areas, sometimes several races at one place (Ruttner and Ruttner 1972). One study showed that drones tend to have fidelity to a particular DCA during mating flights. Of the 446 drones caught a second time at each of two congregation areas 1.2 km apart, 90.8% had been previously caught at the same DCA, and only 9.2% at the other. The frequency with which drones switched from one DCA to another was higher if both congregation areas were in about the same direction from the apiary (but at different distances) and lower if they were in very different directions. Individual drones were caught at the same DCA more than five weeks after their first capture.
Drone congregation areas are commonly visited by drones from almost every apiary in the neighborhood, although ground elevation changes between the DCA’s and the apiary may reduce or prevent approach flights. In mountain districts at least, there appears to be no correlation between the number of drones in the congregation area and the distance from the apiary. Areas as far as five km from an apiary may be visited regularly by numerous drones; some drones were found coming from more than six km away. It is suggested that drones my orient themselves by means of near and distant physical features of the landscape (Ruttner and Ruttner 1966). Apparently a mountainous terrain negatively impacts the formation of flyways and congregation areas.
In flat country, it was impossible to get pure matings if there were other colonies in the neighborhood; at least 6 km must be free of bees or inhabited by the same strain in order to prevent crossing. A physical barrier of over 500 m seemed to be necessary to prevent colonies as close as three km away from intermingling. Drones, and apparently also queens, will not willingly fly over water (Ruttner and Ruttner 1965b).
The flying space of a DCA typically varies from 98 to 656 feet in diameter (30-200 m) with a height of 33 to 131 feet (10-40 m). The flight altitude of drones within a congregation zone is inversely related to wind velocity (Loper et al. 1992). Although the number of drones in a congregation area is quite variable, one such area had an estimated 25,000 drones from more than 200 colonies (Winston 1987). Several regularly frequented DCA’s were observed 500-1000 m from the nearest apiary. In these areas the hum of flying drones was distinctly audible, but visible only when the drone formations were pursuing queens.
Baudry et al. (1998) sampled and studied the parentage of 142 drones collected in a DCA near Oberusel, Germany. The sample contained one group of four brothers, six groups of three brothers, 20 groups of two brothers and 80 singletons. From the sample it was determined that the composition of the DCA contained equal representation from the local colonies, approximately 240 in number. Considering the density of colonies around the congregation area and average flight ranges of males, the results suggested that most colonies within the recruitment parameter of a DCA delegated equal proportions of males to a DCA. Consequently, the relatedness of a queen to her mates – and ultimately the inbreeding coefficient of the progeny – should be minimal. The relatedness among the drones mated to a common queen is also very low, maximizing the genetic diversity among the different patrilines (paternal sub-families) of a colony.
http://www.exmoorbeesandbeehives.co.uk/ Buckfast UK.
What a great overview. Thanks.