Looking for biomarkers of health status in the hemolymph of Apis mellifera

The demographic decline of honeybees (Apis mellifera) determines negative effects not only for agriculture and apiculture, but also for the ecosystems. For this reason, it is mandatory to understand the determinants causing the decline and to establish objective criteria to evaluate their health status. Proteins in the hemolymph may represent a source of valuables biomarkers to assess the health status of the hive; however, they are still poorly investigated. The aim of this study is to separate, to identify the most abundant proteins in the hemolymph, and to identify biomarkers of health status that could help beekeepers and veterinarians in the management and treatment of the hives. Four apiaries were chosen for this research, characterized by different management and location (A= hill, B and D= plain, C= apiary subjected to nomadism). In each apiary, three hives were selected and bees were collected in June, July, August, September, and October. Then 2 µL of hemolymph were withdrawn from each bee and the total proteins were determined by the Bradford method. The proteins of the hemolymph were separated using the SDS-PAGE electrophoresis and identified using mass spectrometry. Colony-level traits (areas covered with bees, brood, sealed brood and pollen) were also estimated. In the hemolymph of honeybees, 20 proteins were identified and among these, five proteins showed relevant variations. These are vitellogenin, apolipophorin, hexamerin, transferrin and prophenoloxidase. In particular, in October, the apiary C presented worst general conditions and a lower population associated with lower concentrations of total proteins, apolipoforin and vitellogenin. The apiary D, on the contrary, had the best trophic and health conditions, associated with higher concentrations of all the aforementioned five proteins. Thereby, it is possible to hypothesize that these proteins may be valuables biomarkers of health status, and it is worthy to continue their study