About this Research Topic
Arthropods are the most successful group of metazoa. Insects alone account for more than one million species and they show a wide spectrum of behavioral and feeding patterns. From this enormous pool of genetic diversity, ~14,000 species, scattered among 400 different genera, have developed the capacity to feed on vertebrate blood (hematophagy). This trait evolved independently, most likely at least six times, during the Jurassic and Cretaceous periods (145-65 million years ago). Of the four main insect orders containing hematophagous species (Diptera, Hemiptera, Phthiraptera, and Siphonoptera), the Diptera are the most important because they are vectors of many devastating human and animal diseases.
Hematophagy in insects contributes principally to reproductive success and has required substantial evolutionary adaptation to accommodate behavior, digestion, iron detoxification, proteins and lipid transport and water management, among other demands. Moreover, the insect must overcome several challenges associated with blood feeding that include: platelet aggregation, vasoconstriction, blood coagulation and immune reactions that can prevent feeding success. Insects have evolved a salivary chemical mixture containing several active compounds to disarm their host’s hemostasis and inflammation. Notably, in addition to facilitating blood feeding, saliva components have been linked to the efficient transmission to human hosts of several pathogens. Vector-borne diseases account for more than 17% of all infectious diseases, causing more than 1 million deaths annually.
Successful pathogen transmission requires an insect feeding on an infected vertebrate host, subsequent infection of the midgut cells and dissemination throughout the rest of the body. The insect becomes infectious to a human host when the pathogen reach the salivary glands and are transmitted via saliva during a second feeding. Vector competence is the intrinsic ability of a hematophagous insect to become infected following ingestion of infected blood and to subsequently transmit the pathogen. Hematophagous insects are phenotypically polymorphic, varies in allele types and frequencies as detected by biochemical and molecular-genetic markers, and exhibits variation in vector competence for pathogens. Understanding the degree to which pathogen evolution and genetic variation in host resistance traits play a role in disease emergence events in natural systems will improve efforts to manage future diseases risks for human populations and in natural systems. The convergent evolution of hematophagy supports the diversity of forms and lifestyles seen in modern day insects as well as their complex relationships with vertebrates. Although several reports documented baseline information on genomic, transcriptomic, and proteomic profiles relevant to basic biology of hematophagous insects; the nature of the non-hematophagous ancestors and how those antihemostatic mechanisms evolved remain unclear. Moreover, understanding the evolution of antihemostatic strategies and pathogen selection pressures could contribute in the knowledge of how hematophagy can impact population dynamics and how these evolutionary mechanisms create and shape diversity in hosts and pathogens and its influence in vector competence.
Manuscripts with original research in any aspect of genetics and/or transcriptomics, proteomics and metabolomics of insect hematophagy will be considered. This Research Topic particularly welcomes manuscripts focusing on broad issues of hematophagy evolution, as well as aspects of genetic conservation, phylogeny and vector competence.
Keywords: Hematophagy, evolution, vector competence, insects, pathogen interaction
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