Genomics of Cochliomyia hominivorax (Diptera: Calliphoridae): structural and functional analyses.

Abstract

The New World screwworm (NWS), Cochliomyia hominivorax, Coquerel 1858 (Diptera: Calliphoridae), is considered as one of the most important pests of livestock in South America, accounting for severe losses in animal production. The larval stages of this species feed on living tissues in wounds of warm-blooded animals, both wild and domestic, after hatching from eggs laid by adult females. Infestation caused by the screwworm fly is called myiasis, which in living vertebrates is caused by larvae of flies that feed on living tissue (primary myiasis) or dead (secondary myiasis) of the host (Zumpt, 1965). In the Neotropics, the only species causing primary myiasis is the screwworm fly, standing out among calliphorids of medical and veterinary importance by being a mandatory ectoparasite species of vertebrate animals, including man (Zumpt, 1965; Guimarães et al., 1982; Azeredo & Lessinger-Espin,2006).The current distribution of C. hominivorax includes South America and some Caribbean islands; the insect has previously been eradicated from North and Central America (continental terrritory) between 1957 and 2000 by the sterile insect technique(SIT) (Klassen and Curtis, 2005). The importance of NWS as a livestock pest, coupled with its ability to spread and adapt, justifies the continued investment in its monitoring, treatment, and control. It is extremely important to perform basic studies on its genetics and ecology. Further, its status as a species model for a successful SIT control program motivates studies to show biological patterns comparable to other pest species. The scientific history of the Laboratory of Genetics and Animal Evolution (LabGEA/UNICAMP) shows the efforts required to generate data and characterize populations of the screwworm fly and related species of the Calliphoridae family. These studies involve the characterization of population structure and dynamics, biogeography, molecular mechanisms of genetic resistance to insecticides, phylogeny, and evolution of parasitic behavior in this species in a broader context. The approaches proposed in this project continue this line of research involving evolutionary and comparative studies by sequencing the complete genome of C. hominivorax. The information generated, provides population genomics and functional analysis via the characterization of microRNA expression profiles in the different phases of development of C. hominivorax. The use of next-generation sequencing platforms will generate the basic data to be applied to specific subprojects. The proposal is organized into three subprojects focusing on the different biological issues to be investigated, with specific objectives and methods. The subprojects are (1) Sequencing the genome of C. hominivorax; and (2) Profile analysis of microRNA expression at different stages of development of C. hominivorax. These approaches focus on the elucidation of critical issues that will be based on the work conducted in C. hominivorax. Using these approaches, we hope to contribute to a better understanding of parasitic behavior of C. hominivorax, with prospects of functional, comparative, and evolutionary studies in Calliphoridae. From a practical point of view, these studies should help in the development of more effective strategies for controlling this pest in Brazil and other regions from South and Central America. (AU)