1Precursory Research for Embryonic Science and Technology (PRESTO) "Intelligence and Synthesis", Japan Science and Technology Corporation (JST): c/o National Institute of Sericultural and Entomological Science (NISES), 1-2 Oowashi, Tsukuba, Ibaraki, 305-8634, Japan. 2Institute of Applied Biochemistry, University of Tsukuba, 1-1-1 Ten-nou dai, Tsukuba, Ibaraki 305-8572, Japan.
The Japanese honeybee (Apis cerana japonica Rad.: Acj) and the European honeybee (A. mellifera L.: Am) have been sharing the same habitat in Japan. The purpose of this study is to elucidate the mechanism of inter- (nest mate) and intra- (invaders, parasitic mite) specific recognition and changes in recognition, by identification(s) of semiochemicals that are responsible for the recognition. (1) A parasitic mite, Varroa jacobsoni Oud., originally an ecto-parasite of A. cerana, is becoming a major culprit of the world-wide decrease of Am colonies after the expansion of its host range by human activity. Acj worker perform hygienic allo-grooming behavior against Varroa and the population of the mite is kept low in the colony. By chemical analyses and bioassays, we have identified the chemical cue for Acj workers to perform grooming behavior. The fact that the older workers responded more frequently and intensely against Varroa as well as against the chemical cue suggests that JH may be responsible for the changes in recognition of the chemical cue from Varroa. (2) Both workers were introduced to their own hive, to other conspecific hives, and to hives of the other species. Am accepted 88% of day-0 Am workers and more than 52 % of the Acj foragers. On the other hand, Acj accepted almost all foragers from the other hive (96%) and day-0 Am workers as well (90%). As a result, nest mate recognition in Acj was milder than that of Am. Hydrocarbons were analyzed by GC and GC/MS, and were compared among two species, using workers and drones. Hydrocarbon profiles among individual workers and drones of a hive were noticed to be different in Acj and Am respectively. Those from drones were divided into groups, of one or two, whereas those from workers were divided into groups of 3 to 10, depending possibly on the queen's multiple mating. These results suggest that nest mate recognition are very complicated.