Although pollinator declines are a global biodiversity threat, the demography of the western honeybee (Apis mellifera) has not been considered by conservationists because it is biased by the activity of beekeepers. To fill this gap in pollinator decline censuses and to provide a broad Keywords:Apis mellifera, beekeeping, ecosystem functioning, honeybee conservation, land use, pollinator decline Estimación de la Densidad de Colonias de Abejas en su Rango Natural para Cerrar la Brecha en los Censos del DeclivePalabras Clave: apicultura, Apis mellifera, conservación de abejas, declive de polinizadores, funcionamiento del ecosistema, uso de suelo
SUMMARY The nutritional needs of bees are supplied by nectar carbohydrates and by protein and other nutrients in pollen but little is known of how bees achieve nutritional balance. Using newly emerged caged worker honeybees (Apis mellifera scutellata), we investigated whether bees maintain their intake target when confined to pairs of imbalanced complementary diets varying in protein to carbohydrate (P:C) ratio. Diets were formulated using three protein sources [casein, royal jelly or Feed-Bee® (a natural pollen substitute)] and sucrose. Within each protein type, honeybees switched between complementary diets and converged on the same P:C intake target. However, this target differed between protein types: P:C ratios were 1:12, 1:14 and 1:11 on casein, royal jelly and Feed-Bee® diets, respectively. Except for an early peak in protein consumption on royal jelly diets, these strongly convergent ratios remained constant over the 14 day experiment. This is probably due to the absence of brood, reflected in relatively stable values measured for haemolymph protein concentration and hypopharyngeal gland activation in bees on Feed-Bee® diets. Performance of caged workers was also assessed in terms of survival and ovarian activation. Survival was highest on casein diets and lowest on Feed-Bee® diets but ovarian activation was highest on royal jelly diets and lowest on casein diets. This may be due to additional components in Feed-Bee® and royal jelly (e.g. fatty acids), which are needed to activate the ovaries but also reduce survival. Nutrient intake of broodless workers is directly related to their own physiological requirements, and the strong carbohydrate bias may reflect the high metabolic rate of honeybees even under resting conditions.
The density of wild honeybee colonies (Apis mellifera) in the African dry highland savannahs was estimated in three Nature Reserves in Gauteng, South Africa (Ezemvelo, Leeuwfontein, Suikerbosrand) based on the genotypes of drones which were caught at drone congregation areas. Densities were estimated to range between 12.4 and 17.6 colonies per square kilometer. In addition colony densities were estimated in two German National parks (Müritz and Hochharz) and a commercial mating apiary. The density of colonies was significantly lower at the German sampling sites with estimates of 2.4-3.2 colonies per square kilometer, which closely matches the nation-wide density of colonies kept by beekeepers. This shows that the densities of colonies observed in wild populations under the harsh conditions of the African dry savannahs exceeds that of Germany by far, in spite of intensive beekeeping. The intensity of apiculture in Europe is therefore unlikely to compensate for the loss of habitats suitable for wild honeybees due to agriculture, forestry and other cultivation of land.openUP
SummaryThis study reports honey bee, Apis mellifera L., colony losses that occurred in South Africa over two consecutive years. The total losses were 29.6% (95% CI: 22.8-37.5) in 2009 and 46.2% (95% CI: 37.3-55.0) in 2010. Furthermore, the study shows that the capensis worker social parasite, a problem unique to southern Africa, is the main perceived cause, and could explain the significant differences in the number of losses between beekeepers using the subspecies A. m. scutellata and those using the subspecies A. m. capensis. In contrast to previous studies in North America and Europe, we find a significant negative effect of migratory beekeeping practices on the extent of colony losses. Migratory beekeepers lost on average more colonies (35.5% (95% CI 29.7-47.2)) than did stationary beekeepers (17.2% (95% CI 11.2-22.3)). This was especially pronounced when the beekeepers were migrating for the pollination of apples/cherries, eucalyptus, onions and/or sunflowers. The major beekeeper-perceived causes of mortality were small hive beetles, varroa mites, absconding (non-reproductive swarming), and chalkbrood disease. Those listing chalkbrood disease lost significantly fewer colonies than those who did not list chalkbrood.The exact mechanism for this difference is unknown, and may be related to other beekeeping practices that correlate with finding chalkbrood infections -namely more intensive inspection and management. Estudio de pérdidas de colonias de abejas manejadas en la República de Sudáfrica -de 2009 a 2011 ResumenEste estudio informa sobre las pérdidas de colonias de abeja de la miel, Apis mellifera L., que tuvieron lugar en Sudáfrica durante dos años consecutivos. Las pérdidas totales fueron del 29.6% (IC 95%: 22.8-37.5) en el período 2009-2010 y el 46.2% (IC 95%: 37.3-55.0) durante el mismo periodo de 2010 a 2011. Además, el estudio muestra que el parásito social capensis, un problema exclusivo de África del sur, es la principal causa percibida que podría explicar las diferencias significativas en el número de pérdidas entre los apicultores que utilizan la subespecie A. m. scutellata y los que usan la subespecie A. m. capensis. En contraste con estudios anteriores en los Estados Unidos, hemos encontrado un efecto de las prácticas de la apicultura migratoria en la magnitud de las pérdidas de colonias. Los apicultores trashumantes perdieron en promedio más colonias 35.5% (IC del 95%: 29.7 a 47.2) que los apicultores estacionarios 17.2% (IC 95%: 11.2-22.3). Esto fue especialmente pronunciado cuando los apicultores estaban migrando para la polinización de manzanas/cerezas, eucalipto, cebolla y/o girasol.Las principales causas de mortalidad percibidas por los apicultores fueron el pequeño escarabajo de la colmena, el ácaro Varroa, la fuga de enjambres (enjambrazón no reproductiva), y la enfermedad ascosferosis. Aquellos que reportaron ascosferosis perdieron significativamente menos colonias que aquellos que no la enumeraron. El mecanismo exacto de esta diferencia no se conoce, y puede estar relacionado con ot...
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