Abstract

IBANEZ-PALACIOS, Jorge; GARCIA-VELAZQUEZ, Armando; ZEPEDA-CISNEROS, Cristina S.  and  CORONA-TORRES, Tarsicio. Karyotype analysis and differentiation of sex chromosomes in four Anastrepha species (Diptera:Tephritidae). Agrociencia [online]. 2010, vol.44, n.6, pp.691-700. ISSN 2521-9766.

The genus Anastrepha Schiner, endemic to tropical and subtropical América, includes the species Anastrepha ludens, A. obliqua, A. striataandA. serpentina, which are polyphagous and parasite a wide range of plants. These species were studied because of their broad geographic distribution and because they parasite different fruit species. Larvae in their third stage reared in the laboratory of the Programa Moscafrut in Metapa de Domínguez, Chiapas, México, were used. The cerebral ganglia were dissected in an aqueous solution of 1% (w/v) sodium citrate in which they were kept for 20 min, then transferred to methanol:acetic acid (3:1 (v/v) and macerated in 60% acetic acid. One drop of this tissue suspension was placed on a slide on a hot plate (45-50°C) and observed with a microscope (Zeiss Axioskop 40) with phase contrast, and the cells with disperse chromosomes were selected. These were photographed with an AxioCam camera and Axiovision 4.0 software, and measurements were taken with Image Tool 3.0. Twenty cells/sex/species were analyzed. The centromere was observed without pretreatment. Karyotypes were determined in each species: A. ludens , 2n=12, Xg Xg+V_II telo, n. f. 12, , 2n=12, Xg Yp+V_II Telo n. f. 12; A. obliqua , 2n=12, Xg Xg+V_II Telo, n. f. 12, , 2n=12, Xg Yg+V_II Telo n. f. 12; A. striata , 2n=12, Xg Xg+II_II Meta+III_II Telo n. f. 16, , 2n=12, Xg Yp+II_II Meta+II_II Telo n. f. 16; A. serpentina , 2n=12, X₁ X₁ X₂ X₂+IV_II Meta n. f. 20, , 2n=11 X₁ X₂, Yg+IV_II Meta n. f.22. It is proposed that this group of species has Robertsonian translocations as a speciation mechanism parting from A. serpentina.

Keywords : Anastrepha ludens; A. obliqua; A. striata; A. serpentina; evolution; genomes; fruit flies.