CONICET | Buscador de Institutos y Recursos Humanos

Phylogeographic studies in populations of Nezara viridula could provide useful information to optimize the control strategies. The comparative analysis of a fragment of 718 bp of the citocromo oxidase I (COI) gene in 98 individuals from Argentina revealed limited levels of nucleotide and haplotype diversity (π = 0.00039 and Hd = 0.138, respectively). In samples from soybean crops only the common and most frequent haplotype was observed; while in samples obtained from mixed crop (soybean and maize) and a peanut crop, exclusive haplotypes of low frequency were also detected. It is probable that during the reduction of the populations produced by the intense insecticide exposure that characterizes soybean crops, very low frequency haplotypes would be lost faster. Neutrality tests indicated population expansion in the samples from the mixed crop and the peanut crop. It is probable that these N. viridula populations, belonging to crops with lower insecticide requirements, were expanded recently and that the gene flow levels and time elapsed were not enough to disperse the exclusive haplotypes. A phylogenetic analysis using COI gene sequences available from the GenBank of populations from Europe, South America, Asia, and Africa revealed that the haplotype detected in Africa was separated by numerous mutational steps and presented a basal position in the phylogenetic tree. These results are consistent with previous studies supporting the hypothesis of an African origin of N. viridula. The haplotype network, the phylogenetic tree, and a Bayesian method of grouping individuals revealed that individuals from Japan were grouped with individuals from Brazil. In adition, the haplotypes from Europe and South America formed another haplogroup. The results obtained are consistent with previous studies, suggesting a colonization from Europe to the coasts of South America and that in more recent times could have existed gene exchange between South America and Japan.