RESUMEN
The objective of the study was to examine the dynamics and sugar content of nectar of major bee flora species and to determine an approximate honeybee colony carrying capacity in northeast dry land areas of the Amhara region. Acacia asak, Acacia etbaica, Acacia tortolis, Becium grandiflorum, and Cordia africana honeybee floral species were selected on the basis of relative dominance in the area. Floral nectar was collected through micropipette and washing techniques based on the flower nature of the species and nectar sugar was measured by refractometer. Hence, A.asak, A.etbaica, A.tortolis, B.grandiflorum, and C.africana could have been estimated to produce 10.2 ± 6.4 mg, 5.3 ± 4.6 mg, and 2.6±1 mg. 4, 3.7 ± 2.1 mg, and 5.7 ± 3.2mg/flower head of nectar sugar, respectively. In a single tree of A.etbaica, A.asak, A.tortolis, B.grandiflorum, and C.africana a mean of 0.15 kg, 0.15 kg, 0.06 kg, 0.01 kg, and 0.03 kg of honey yield was expected to produce respectively. Similarly in a hectare of land, a mean of 49.9 kg, 128.9 kg, 5.6 kg, 5.5 kg, and 2.2 kg of honey was estimated to harvest. In a hectare of land a sum of 57.5 kg, 57.5 kg, and 128.9 kg of honey in highland, midland, and lowland locations, respectively was estimated to produce during the main harvesting season of the area. The mean number of honeybee colonies introduced in the lowland have estimated to be 18 traditional, 6 transitional, and 5 modern hives, and in the highland 12 traditional, 6 transitional, and 5 modern hives whereas in the midland 8 traditional, 5 transitional, 3 modern hives. In summary, even in the study area with limited rainfall and high temperatures, these species secreted a substantial amount of nectar sugar and supporting the enhancement of honey yield.
RESUMEN
In this article, we report the pathogenicity of a new strain of fungus, Rhizopus oryzae to honeybee larvae, isolated from the chalkbrood-diseased mummies of honeybee larvae and pupae collected from apiaries in China. Based on morphological observation and internal transcribed spacer (ITS) region analyses, the isolated pathogenic fungus was identified as R. oryzae. Koch's postulates were performed to determine the cause-and-effect pathogenicity of this isolate fungus. The in vitro pathogenicity of this virulent fungus in honeybees was tested by artificially inoculating worker larvae in the lab. The pathogenicity of this new fungus for honeybee larvae was both conidial-concentration and exposure-time dependent; its highly infectious and virulent effect against the larvae was observed at 1 × 105 conidia/larva in vitro after 96 h of challenge. Using probit regression analysis, the LT50 value against the larvae was 26.8 h at a conidial concentration of 1 × 105 conidia/larva, and the LC50 was 6.2 × 103 conidia/larva. These results indicate that the new isolate of R. oryzae has considerable pathogenicity in honeybee larvae. Additionally, this report suggests that pathogenic phytofungi may harm their associated pollinators. We recommend further research to quantify the levels, mechanisms, and pathways of the pathogenicity of this novel isolated pathogen for honeybee larvae at the colony level.