Insect immune resistance to parasitoids

Abstract

Insect host—parasitoid interactions involve complex physiological, biochemical and genetic interactions. Against endoparasitoids, immune‐competent hosts initiate a blood cell‐mediated response that quickly destroys the intruders and envelops them in a multilayered melanotic capsule. During the past decade, considerable progress has been made in identifying some of the critical components of the host response, mainly because of the use of efficient molecular tools. This review examines some of the components of the innate immune response of Drosophila, an insect that has served as an exceptionally good experimental model for studying non‐self recognition processes and immune cell signaling mechanisms. Topics considered in this review include hematopoiesis, proliferation and adhesion of hemocytes, melanogenesis and associated cytotoxic molecules, and the genetic aspects of the host‐parasitoid interaction.

Extracellular Superoxide Dismutase in Insects

“…After recognition, the egg is indeed rapidly covered by host hemocytes that likely produce killing oxygen radicals (54). Also, lamellocytes, the main forming-capsule hemocytes, specifically express the PO3 gene (55,56), and a deposit of melanin, indicating PO activity, is observed at the surface of the parasitoid egg (3,57,58).…”

“…To ensure successful parasitism, they inject with the egg various components, including venom factors that alter the host immunity and/or manipulate its development and physiology (1,2). The typical host immune defense against parasitoids is the formation of a multicellular melanized capsule around the egg, which requires the coordination of cellular and humoral components (3,4). After egg parasite recognition, host hemocytes proliferate, become adhesive, attach and spread at the surface of the egg (5).…”

Proteome changes in the plasma of Papilio xuthus (Lepidoptera: Papilionidae): effect of parasitization by the endoparasitic wasp Pteromalus puparum (Hymenoptera: Pteromalidae)

“…Some investigators are analyzing the host transcriptional response to parasitoid attack. A large number of differentially expressed genes related to parasitism have been identified by employing mRNA-based approaches such as microarray and amplified fragment length polymorphism (AFLP) to measure message abundance (Reineke and Löbmann, 2005;Wertheim et al, 2005;Barat-Houari et al, 2006;Schlenke et al, 2007;Carton et al, 2008). Despite increasingly available information on the alteration of host gene transcription caused by parasitism, little is known on the alterations of proteins (Dong et al, 1996;Nakamatsu et al, 2006;Salvador and Cônsoli, 2008).…”

Dual effect of nitric oxide on phenoloxidase-mediated melanization

“…The penetration of pathogen into an organism initiates the melanization cascade which finally results in the formation of a melanin capsule around the pathogen 3,4 . The particular mechanisms of triggering and regulation of this process were active studying 5 , but many aspects are still unclear.…”