Incongruent Nuclear and Mitochondrial Genetic Structure of New World Screwworm Fly Populations Due to Positive Selection of Mutations Associated with Dimethyl- and Diethyl-Organophosphates Resistance

Author(s)

Bergamo, Luana Walravens ^{[1, 2]} ; Fresia, Pablo ^[1] ; Azeredo-Espin, Ana Maria L. ^{[1, 2]}

Affiliation

^[1] Univ Estadual Campinas, CBMEG, Campinas, SP - Brazil

^[2] Univ Estadual Campinas, IB, DGEB, Campinas, SP - Brazil

• Document type: Journal article
• Source: PLoS One; v. 10, n. 6 JUN 1 2015.
• Web of Science Citations: 5

Abstract

Livestock production is an important economic activity in Brazil, which has been suffering significant losses due to the impact of parasites. The New World screwworm (NWS) fly, Cochliomyia hominivorax, is an ectoparasite and one of the most important myiasis-causing flies endemic to the Americas. The geographic distribution of NWS has been reduced after the implementation of the Sterile Insect Technique (SIT), being eradicated in North America and part of Central America. In South America, C. hominivorax is controlled by chemical insecticides, although indiscriminate use can cause selection of resistant individuals. Previous studies have associated the Gly137Asp and Trp251Leu mutations in the active site of carboxylesterase E3 to resistance of diethyl and dimethyl-organophosphates insecticides, respectively. Here, we have sequenced a fragment of the carboxylesterase E3 gene (ChaE7), comprising part of intron iII, exon eIII, intron iIII and part of exon eIV, and three mitochondrial gene sequences (CR, COI and COII), of NWS flies from 21 locations in South America. These markers were used for population structure analyses and the ChaE7 gene was also investigated to gain insight into the selective pressures that have shaped its evolution. Analysis of molecular variance (AMOVA) and pairwise FST analysis indicated an increased genetic structure between locations in the ChaE7 compared to the concatenated mitochondrial genes. Discriminant analysis of principal components (DAPC) and spatial analysis of molecular variance (SAMOVA) indicated different degrees of genetic structure for all markers, in agreement with the AMOVA results, but with low correlation to geographic data. The NWS fly is considered a panmitic species based on mitochondrial data, while it is structured into three groups considering the ChaE7 gene. A negative association between the two mutations related to organophosphate resistance and Fay \& Wu's H significant negative values for the exons, suggest that these mutations evolved under positive selection. (AU)

• FAPESP's process: 12/11654-9 - Insecticide resistance characterization in the New World screwworm fly, Cochliomyia hominivorax: molecular and populational approaches
• Grantee: Ana Maria Lima de Azeredo-Espin
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/15739-6 - Evolution of the esterase E3 gene: evaluation of the effects of selection and geographical distribution of mutations associated with resistance to insecticides in Cochliomyia hominivorax (Diptera: Calliphoridae)
• Grantee: Luana Walravens Bergamo
• Support Opportunities: Scholarships in Brazil - Master