Effects of ensiling on the quality of protein supplements for honey bees Apis mellifera

We developed a nutritious, palatable, and attractive fermented diet as supplementary food for honey bees (Apis mellifera) during periods of natural food scarcity. Two types of commercial silage inoculants were tested; bacteria and a mix of bacteria and fungi were used to ferment a protein-based feed for 7, 14, or 28 days. The positive control consisted of beebread and the negative controls were sucrose solution 50%, w/v) and the unfermented protein diet. These feeds were offered, 4 g each, along with sucrose solution ad libitum, to 60 worker bees confined in plastic cages (seven replicates, 7 days). A pool of 20 bees/cage was collected on the first day (day 0) and on the 7th day of the experiment, for protein quantification by the Bradford method and for the electrophoretic profile of the proteins by SDS-polyacrylamide gel electrophoresis. The diets fermented for 7 days were the most consumed when compared with unfermented protein diet and with beebread. All the bees that ate the fermented feeds (except for the 28-day fermentation period) presented higher titers of protein in the hemolymph when compared with the bees that did not consume any protein food (negative control and day 0). The electrophoretic analysis presented a protein profile compatible with good protein expression in the hemolymph of the bees that consumed the fermented feeds, in comparison with bees that had no access to a protein diet. Consequently, we conclude that fermenting protein supplements with silage inoculants is a viable alternative for producing protein diets that are nutritious and palatable for honey bees.