Humoral and Cellular Defense Mechanisms in Rebel Workers of Apis mellifera

Abstract

The physiological state of an insect depends on efficiently functioning immune mechanisms such as cellular and humoral defenses. However, compounds participating in these mechanisms also regulate reproductive caste formation and are responsible for reproductive division of labor as well as for labor division in sterile workers. Divergent reaction of the same genotype yielding reproductive queens and worker castes led to shaping of the physiological and behavioral plasticity of sterile or reproductive workers. Rebels that can lay eggs while maintaining tasks inside and outside the colony exhibit both queen and worker traits. So, we expected that the phagocytic index, JH3 titer, and Vg concentration would be higher in rebels than in normal workers and would increase with their age. We also assumed that the numbers of oenocytes and their sizes would be greater in rebels than in normal workers. The rebels and the normal workers were collected at the age of 1, 7, 14, and 21 days, respectively. Hemolymph and fat bodies were collected for biochemical and morphological analyses. The high levels of JH, Vg, and the phagocytic index, as well as increased numbers and sizes of oenocytes in the fat body cells demonstrate the physiological and phenotypic adaptation of rebels to the eusocial life of honeybees.

Morphology of Nasonov and Tergal Glands in Apis mellifera Rebels

“…Moreover, dysfunction of the Nasonov glands in rebels can lead to functional disorders related to social immunity (e.g., the removal of dummies) [ 50 ]. These mechanisms are controlled by the juvenile hormone and vitellogenin, the concentrations of which in rebels are much higher than in normal workers [ 51 ].…”

An Efficient and Simple Method for Collecting Haemolymph of Cerambycidae (Insecta: Coleoptera) Adults

“…At the same time, there are more fat bodies in the haemocoels of insects, which are relatively large organs distributed in the whole body [ 31 ]. They are preferentially distributed under the coat, surrounded by intestinal and reproductive organs, and are the most common components in the internal anatomy [ 32 ]. Hence, the mixing of fat with haemolymph can also affect the purity of extracted haemolymph.…”

“…For example, the observed total protein contents were not consistent with our expectations. The total protein content should be positively correlated with the cell content in the haemolymph [ 32 ]. Haemolymph with higher turbidity contains more substances and more protein [ 44 ].…”

The Morphological Image of Fat Body and Tergal Gland Cells in Uninseminated Apis mellifera Queen Bees

“…A high density of individuals, and high humidity and temperature, make both adult insects and their developmental forms vulnerable to pathogen activities. Under such conditions, only the high efficiency of immunity mechanisms ensures the survival of bees [6][7][8][9]. The penetration of toxic compounds or pathogens into the hemolymph disrupts metabolism and affects the immune protein synthesis pathways [5].…”

“…In the bee body, Vg is captured by specific groups of cells and is involved in various physiological processes, e.g., stress reduction, lifespan regulation, reproduction; metabolic processes, e.g., regulation of juvenile hormone concentration; and behavioral processes, e.g., feeding. The largest amount of vitellogenin is produced by the fat body of nurse bees, but even then it is only 1/20th of the queen bees' vitellogenin levels [9,13,[16][17][18][19][20]. The number of eggs laid by the queen depends on the concentration of Vg.…”