Evolution of sequence and expression of the olfactory receptors (ORs) related to feeding habits in the Calliphoridae family

Abstract

Parasitism is one of the most successful feeding habits, and is displayed by several different species. The Diptera order is very diverse, being composed by the true flies. Within Diptera, the blowflies, present a wide diversity of feeding habits, including ectoparasitism. The infestation of live vertebrate hosts by ectoparasite flies is called myiasis, which can be caused by representants of Chrysomya and Cochliomyia genera. This type of feeding habit has appeared in different occasions in the evolutionary story of the Calliphoridae family. In insects, olfaction is responsible for the perception of food, predators and possible mating pairs. Differences in the transduction pathways from olfactory messages to neural electrical activities may have contributed to the appearance of distinct feeding habits. The olfactory receptors (ORs) are one of the components of sensory neurons and participate in the olfactory cascade. The ORs are diverged members of a protein superfamily characterized by seven transmembrane domains, that share little similarity between sequences. This multigenic family appeared from a series of duplications followed by adaptive and neutral mutations on an ancestral gene. The ORs functions are imperative in the determination of feeding habits, which make them good candidates for the study of the evolution of feeding habits in the Calliphoridae family. From the applied point of view, it lays the groundwork for novel control and management of livestock pests that lead to important economic due to the infestation of live hosts. This project aims at the comparative analysis of the sequence and expression of ORs genes in species of the Chrysomya and Cochliomyia genera, and try and correlate their patterns of evolution with theirs feeding habits. (AU)