Effect of feeding Acacia saligna Pollen on Apis mellifera Adult Worker Bees in Northern Ethiopia.

Acacia saligna is a multi-purpose tree. However, enquiries exist among beekeepers on its importance for honeybees in Tigray region of Ethiopia. The aim of this study was to investigate the effects of A. saligna pollen on Apis mellifera adult worker bees. Feeding trial was conducted on honeybee collected polyfloral pollen (PFP), honeybee collected A. saligna pollen (HCAP) and manually collected A. saligna pollen dust (MCAP) at various level of inclusion. The HCAP and MCAP pollen types were mixed with PFP pollen at a ratio of 1:4, 3:2 and 1:0 to make seven pollen feed treatments. Newly hatched day-old cohort worker bees were collected from one colony and trapped from the sealed brood with a meshed plastic bag before hatching. A ten-day indoor cage experiment was carried out after setting up twenty worker bees per cage. The result showed no statistically significant difference on worker bee mortality and abnormality due to treatment diets, except that higher level of A. saligna pollen inclusion (> 60%) in the diet reduced intake. Secondary metabolites analysis showed higher alkaloids (4.8%) in PFP, total flavonoids of 29.66 mg QE/g in HCAP and 20.61 mg GAE/g phenol in MCAP. The finding implied A.saligna has apicultural value as dry season pollen source rather than considering it as poisonous. [ABSTRACT FROM AUTHOR]