Variation in hemolymph content and properties among three Mediterranean bee species

Hemolymph, as mediator of immune responses and nutrient circulation, can be used as physiological marker of an insects health, environmental quality or ecological adaptations. Recent studies reported intraspecific variation in protein contents and biological activities of the hemolymph of honey bees related to their diet. Here we measured interspecific variation in three common bee species in the Mediterranean Basin with contrasting ecologies: Apis mellifera, Chalicodoma siculum, and Xylocopa pubescens. Despite all the bees were collected in the same area, we found important quantitative and qualitative variations of hemolymph extracts across species. Samples of A. mellifera and C. siculum had much higher protein concentration, anticancer, antimicrobial and antoxidant activities than samples of X. pubescens. This first descriptive study suggests life history traits of bee species have strong influences on their hemolymph properties and call for future large scale comparative analyses across more species and geographical areas.