A b s t r a c t The effectiveness of two methods of collecting semen from honeybee Apis mellifera drones was compared, and the reasons for problems with ejaculating semen were analysed. Among 275 drones, 100 were stimulated to release semen using a manual method, 100 with the use of chloroform, and from 75 drones the reproductive organs were dissected for analysis and evaluation. It was found that the principal causes of problems that drones had with ejaculating their semen were anatomical changes or a delay in the development of the mucus glands. It was also found that the method employing chloroform was less efficient in the first phase of eversion of the endophallus, compared with the manual method. The method with the use of chloroform allows the determination of the proportion of drones, which do not evert the endophallus because of poor or delayed development of mucus glands, as well as the proportion of drones which evert the organ, but do not ejaculate semen because of the absence of semen in the seminal vesicles.Keywords: Apis mellifera, drone, eversion, reproductive organ.
INTRODUCTIONIn a honeybee colony drones are responsible for producing semen and transmitting it to the queen during copulation. In drones, the spermatozoa are produced in the pre-imago stage of development. In the first days of a drone's life the spermatozoa are moved from the testes to the seminal vesicles, where they are stored until mating. Immediately after emerging from the cells, drones are not able to copulate. They reach the ability to mate in 9 -12 days after emergence (Bishop, 1920;Ruttner and Tryasko, 1976). Drones mate with the queen at the age of 15 -23 days, the average being 21 days (Couvillon et al., 2010). Because of the limited number of young queens, only a few drones have the chance to pass on their semen during copulation. The majority of drones die because of age, diseases, or predators (Free and Williams, 1975;Fukuda and Ohtani, 1977;Rueppell et al., 2005;Boes, 2010). A drone does not survive copulation (Witherell, 1965). On average, the drones that do not have the chance to copulate with a queen live 30 days (Rueppell et al., 2005). Colonies differ in terms of the number of drones reared and their reproductive activity (Kraus et al., 2003;Boes, 2010). The reproductive success of drones depends much on the size of the colony and the conditions prevailing during rearing and maturing (Jaycox, 1961;Boes, 2010;Bieńkowska et al., 2011;Mazeed, 2011;Abdelkader et al.;. The drones reared in larger colonies achieve greater reproductive success; more often copulate with the queen, and also have a larger share in the number of offspring (Kraus et al., 2003). The drones reared under optimum thermal and feeding conditions have greater chance of mating (Jaycox, 1961;Rueppell et al., 2006;Czekońska et al., 2013). Drones reared in colonies of different quality, differ in the age when they reach the ability to copulate with the queen (Rhodes et al., 2011;Czekońska et al., 2015). Therefore, in practice, the age of drones is not...