A comparison of bee bread made by Africanized and European honey bees (Apis mellifera) and its effects on hemolymph protein titers

Authors: DeGrandi-Hoffman, Gloria; ECKHOLM, BRUCE - University Of Arizona; HUANG, MING - University Of Arizona

Submitted to: Apidologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2012
Publication Date: 7/18/2012
Citation: Hoffman, G.D., Eckholm, B., Huang, M.H. 2012. A comparison of bee bread made by Africanized and European honey bees (Apis mellifera) and its effects on hemolymph protein titers. Apidologie. 44:52-63 DOI:10.1007/s13592-012-0154-9.

Interpretive Summary: Nutrition plays a key role in the health of all organisms. There are genetic factors that influence an organism’s ability to obtain nutrients from their food. Honey bees obtain their nutrients from pollen and nectar. Pollen is stored in comb cells and converted to a fermented honey and pollen mixture called bee bread. We used two genetically different races of honey bees; European (EHB) and African (AHB) and fed them the same pollen to test for genetic influences on the conversion to bee bread. We also examined the consumption of the bee bread made by both races and resulting hemolymph protein levels. We found that bee bread made by both races was more acidic than the pollen. Bee bread made by EHB was slightly more acidic than AHB. The protein concentration in the bee bread made by either race was similar and significantly lower than in the pollen. In general, amino acid concentrations were higher in bee bread made by either race compared with pollen. The only exception was tryptophan. The concentrations of amino acids were similar in bee bread made by either race except for phenylalanine and cysteine. Levels of phenylalanine were higher in bee bread made by AHB than in either the pollen or bee bread made by EHB. Cysteine concentrations were lower in bee bread made by EHB compared with pollen or bee bread made by AHB. Both AHB and EHB consumed more bee bread made by AHB. Protein concentrations in AHB were higher than in EHB regardless of the source of bee bread. Differences in the ability to acquire protein from bee bread between AHB and EHB might contribute to the successful establishment of AHB populations. This is because higher protein levels in workers can result in greater rates of brood rearing and colony growth. Nutrition plays a key role in the health of all organisms. There are genetic factors that influence an organism’s ability to obtain nutrients from their food. Honey bees obtain their nutrients from pollen and nectar. Pollen is stored in comb cells and converted to a fermented honey and pollen mixture called bee bread. We used two genetically different races of honey bees; European (EHB) and African (AHB) and fed them the same pollen to test for genetic influences on the conversion to bee bread. We also examined the consumption of the bee bread made by both races and resulting hemolymph protein levels. We found that bee bread made by both races was more acidic than the pollen. Bee bread made by EHB was slightly more acidic than AHB. The protein concentration in the bee bread made by either race was similar and significantly lower than in the pollen. In general, amino acid concentrations were higher in bee bread made by either race compared with pollen. The only exception was tryptophan. The concentrations of amino acids were similar in bee bread made by either race except for phenylalanine and cysteine. Levels of phenylalanine were higher in bee bread made by AHB than in either the pollen or bee bread made by EHB. Cysteine concentrations were lower in bee bread made by EHB compared with pollen or bee bread made by AHB. Both AHB and EHB consumed more bee bread made by AHB. Protein concentrations in AHB were higher than in EHB regardless of the source of bee bread. Differences in the ability to acquire protein from bee bread between AHB and EHB might contribute to the successful establishment of AHB populations. This is because higher protein levels in workers can result in greater rates of brood rearing and colony growth.

Technical Abstract: The genetic influence on nutrient acquisition was examined using European and African honey bees (EHB and AHB). Both races collected the same pollen and stored it in comb cells where it was converted to a fermented food called bee bread. We compared pH, protein and amino acid concentrations in the bee bread made by both races. We also examined bee bread consumption and protein acquisition by worker bees of each race. We found that bee bread made by both races had a lower pH than that of the pollen. Bee bread made by EHB was slightly more acidic than that made by AHB. The protein concentration in bee bread made by both races was similar and significantly lower than in the pollen. In general, amino acid concentrations were higher in bee bread compared with pollen. The only exception was tryptophan. Concentrations of amino acids in bee bread made by either race were similar except for phenylalanine and cysteine. Both AHB and EHB consumed significantly more of the bee bread made by AHB than that made by EHB. Protein concentrations in AHB were higher than in EHB regardless of the source of bee bread. Differences in protein acquisition between AHB and EHB might contribute to the successful establishment of AHB populations in the New World because of the effects on brood rearing and colony growth. The role of microbes during the conversion of pollen into bee bread as an explanation for certain differences found in protein and amino acid concentrations are discussed.