Identification and function of the hypotrehalosaemic hormone (Mas-AKH) in workers, drones and queens of Apis mellifero ligustica and A. m. carnica

Abstract

SUMMARYMethanolic extracts of the corpora cardiaca (CC) of foraging workers of the yellow Italian race of honey bees (Apis mellifera ligustica) contained on average 3.0 pmol/pCC (paired corpora cardiaca) of the hypertrehalosaemic hormone, Mas-AKH. The CC of A. m. ligustica nurse bees (8–10 days old) contained only about 1/20th (0.14 pmol/pCC) of the Mas-AKH as that of foragers, and very young bees (2–4 days old) contained no detectable hormone. CC extracts of A. m. ligustica virgin drones and older drones (> 8 days) also contained Mas-AKH, but much less (0.23 pmol/pCC) than foraging worker bees. CC extracts from both virgin and mated (egg laying) ligustica/carnica queens, as well as from foraging workers or drones of the brown European race of honey bees (Apis mellifera carnica) all lacked detectable Mas-AKH or any other related peptides. There was no elevation of the total blood sugar titre in any caste of either ligustica or carnica when injected with either synthetic Mas-AKH or with extracts of their respective corpora cardiaca. The amount of fat body and the amount of stored glycogen is small in all castes of both races. The crop in all castes is large and contained up to 30% of the total body weight. In conclusion, none of the castes of either race seemed to use a hormone to mobilize sugar from the fat body or other glycogen stores (such as the muscle), but rather they depend for all activities entirely on sugars in the crop.