Innate Immunity Pathways

Apis mellifera

Photo credit: Robert Brucker ©2012

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Suborder: Apocrita
Superfamily: Apoidea
Family: Apidae

The honey bee is native to the continents of Europe, Asia, and Africa. As of the early 1600s, the insect was introduced to North America, with subsequent introductions of other European subspecies two centuries later. Since then, they have spread throughout the Americas.


Generally,Apis mellifera are red/brown with black bands and orange yellow rings on abdomen. They have hair on thorax and less hair on abdomen. They also have a pollen basket on their hind legs. Honeybee legs are mostly dark brown/black.There are two castes of females, sterile workers are smaller (adults 10-15 mm long), fertile queens are larger (18-20 mm).

Honeybees build a hive out of wax secretions from their bodies, and queens lay their eggs in cells in the wax.


Honeybee immune system also comprised of cellular and humoral response mechanisms which are regulated by many immunity-related genes . Cellular immunity involves direct interactions between hemocytes (blood cells) and invading organisms. When hemocytes respond to an invasion of the blood cavity by an intruding organism, they must be able to distinguish the invader from the insect's own tissues.

The humoral immune response of honey bees consists of the production of antimicrobial peptides which are active against fungi, bacteria and eukaryotic pathogens. Two main signaling pathways control the expression of genes encoding the formation of these antimicrobial peptides; these are the Imd and Toll pathways, which are activated upon the detection of microbes. The Toll pathway is responsible for defense against fungal and gram-positive bacterial infections, whereas the Imd pathway is primarily involved in defense against gram-negative bacteria. However, these two pathways do interact to co-regulate the peptide, defensin. Anti-microbial peptides are active at low concentrations and exhibit a potent and broad spectrum of activity. Most of these peptides act synergistically at the cell wall membranes by attacking different components of the cell envelope.

All the 4 pathways seems to be conserved in Honey Bees.

Species:    Select Pathway:          



Immunity genes list obtained from:


Immune pathways and defence mechanisms in honey bees Apis mellifera.
Evans JD, Aronstein K, Chen YP, Hetru C, Imler JL, Jiang H, Kanost M, Thompson GJ, Zou Z, Hultmark D.
Insect Mol Biol. 2006 Oct;15(5):645-56.