Wound Responses in Insects

Abstract

For over a century, the study of specific antipathogenic strategies in insects has been confounded by non-specific responses to integumental invasion. Experimental injury to diapausing Hyalophora cecropia silkmoth pupae elucidated some of the events inherent in this response—increased oxygen consumption and DNA and RNA synthesis leading to de novo synthesis of proteins, some of which are constituents of the adult protein cohort as well as some injury-specific ones. The mechanism which enforces diapause is apparently released by integumental injury as well as by normal developmental stimuli. Recent work has concentrated on purification of antipathogenic and injury-specific proteins, the possible involvement of lectins in the immune response, and localization of synthesis of these proteins in hemocytes and fat body cells. At least ten different hemolymph proteins which are synthesized by fat body cells in response to inoculation of lepidopteran species with bacteria currently are being isolated. The hemolymph of H. cecropia contains lectins which are synthesized by hemocytes. Analysis of in vitro incorporation of ['H]leucine by hemocytes into proteins reveals that these lectins apparently are not constituents of the secreted injury response protein complex in fifth instar caterpillars or diapausing pupae, nor are hemolymph lectin titers significantly different in healthy versus diseased or injured animals. However, intracellular lectin concentrations may increase upon injury. Increased lectin titer and induction of bactericidal activity coincide in another holometabolous species, the fleshfly Sarcophaga peregrina . Pursuit of these studies may elaborate our knowledge of insect cellular immunity.