Origin of boll weevil populations in Argentina, Brazil and Paraguay: a hypothesis based on the study of two mitochondrial genes.

CONFALONIERI, VIVIANA ANDREA; SCATAGLINI, MARÍA AMALIA; LANTERI, ANALÍA ALICIA

Fortaleza, Ceará, Brasil

Workshop; Cotton in the Southern Cone. Final International Workshop on Integrated Pest Management of the Cotton Boll Weevil, in Argentina, Brazil and Paraguay.; 2001

SENASA, COMMON FUND FOR COMMODITIES, INTERNATIONAL COTTON ADVISORY COMMITTEE.

The main goal of the present contribution is to test our previous hypothesis on the origin of the boll weevil populations in Argentina, Brazil and Paraguay, based on the RAPD technique, by means of a phylogeographic analysis, using sequences of the mitochondrial genes Cytochrome Oxidase I and II (COI and COII). Phylogeographic studies contribute to understand the evolutionary history of species and its geographic dispersal. One population is considered ancestral when it includes several haplotypes (variants of mitochondrial DNA) and as recent or colonizing , if it has one or few haplotypes. Our results indicate thet populations from Tecomán (Mexico) and Iguazú (Argentina) have the highest number of different COI haplotypes, seven in the former and five in the latter, among ten individuals of each sample. This is typical of ancestral populations established since prehistoric times. In the remaining South American samples the number of haplotypes is lower than in Mexico and Iguazú : four in Londrina (Brazil), two in Pto.Península (Argentina), one in Caacupé (Paraguay) and one in Laguna Naick Neck (Argentina). Accordingly, Londrina would be the population established for longer. The haplotype we have called "A" is present in all samples except those from Tecomán and Iguazú. Therefore, we interpret thet South American populations with "A" haplotype are related to Texas sample, thus, with the "southeastern form" of the boll weevil. On the contrary, the population from Iguazú, coming from a non-cotton growing area, it is genetically different and morphologically closer to the "mexican form" of A. grandis. Results from COII analysis are similar to those based in COI analysis.