Caste and age-related changes in circulatory hemocytes of honey bee, Apis mellifera anatolica (Hymenoptera: Apidae)

Abstract

In recent years, there has been a great concern about increased honey bee losses and this phenomenon has turned into a global issue. Therefore, immune system research on honey bees gained importance. Hemocytes are an important part of the immune system. But there is a limited study about hemocyte types of honey bees. From this point of view, a detailed study was performed on hemocyte types of honey bee Apis mellifera anatolica was described in larval (3rd, 4th and 5th larval instars), prepupal, pupal, and adult stages of all castes including worker, drone, and queen. According to light microscopic examinations, prohemocyte, plasmatocyte, granulocyte, adipohemocyte and oenocytoid were determined in all castes. Prohemocytes are usually rounded cells with a large nucleus and small cytoplasmic area. Plasmatocytes are spherical or oval cells. Granulocytes are generally spherical cells with dense granules. Adipohemocytes are usually spherical cells having numerous lipid droplets within their cytoplasm. Oenocytoides are usually spherical cells with small and spherical nucleus centrally located. Also, we statistically compared the size of hemocyte types among these castes during metamorphosis. According to our measurements, the queen generally had the biggest hemocytes in comparison to the developmental stages in other castes. While statistically significant differences in the sizes of hemocyte types were mainly detected among castes of the pupal stage, there were no statistically significant differences in hemocyte sizes among castes of adult honey bees. In view of these findings, it may be stated that hemocyte profiles of A. m. anatolica vary based on the developmental stages of castes. © 2020 International Bee Research Association.