Insect immunity and its signalling: an overview

The innate immunity is the immediate and sole response of invertebrates for the protection against foreign substances and pathogens. In insects, it relies on both humoral and cellular responses that are mediated via certain recognizing receptors and activation of several signalling pathways. Fat body and hemocytes are the origins for the production and secretion of antimicrobial agents and activators/regulators of cellular response, while cell mediated immunity in insects is performed by hemocytes. In the last years, research has focused on the mechanisms of microbial recognition and activation of intracellular signalling molecules in response to invaders. In this review, we summarize the mechanisms of the innate immunity in insects and refer to potential interactions between humoral and cellular responses, combined with the involving signalling pathways and their cross talk.