Cytogenetic Studies on Workers of the Neotropical AntWasmannia auropunctata(Roger 1863) (Hymenoptera: Formicidae: Myrmicinae)

Abstract

Wasmannia auropunctata is known as one of the worst invasive ants in the World. A cytogenetic study was conducted on two native populations from southeastern Bahia, Brazil. The analysis of the chromosomes observed in mitotic metaphases was made by a combination of methods: Giemsa conventional staining, chromomycin A3 (CMA3) and 4-6-diamidino-2-phenylindole (DAPI) fl uorochrome staining, and acridine orange banding. The workers have all the karyotype 2n=32, with ten pairs of metacentric and six pairs of acrocentric chromosomes. One chromosome arm of the pair ten was positive for CMA3 and acridine orange, suggesting the occurrence of a nucleolar organizing region. This region is an interesting marker because is very conservative and seems to constitute an interesting specifi c taxonomic character. The pericentromeric region of many chromosomes was stained with DAPI, evidencing the occurrence of AT bases rich heterochromatin. Résumé. Études Cytogénétiques sur les Ouvrières de la Fourmi NéotropicaleWasmannia auropunctata (Roger 1863) (Hymenoptera: Formicidae : Myrmicinae). Wasmannia auropunctata est connue comme étant l'une des fourmis les plus invasives du monde. Une étude cytogénétique a été réalisée dans deux populations natives du sud-est de Bahia, Brésil. L'analyse des chromosomes en métaphases mitotiques a été effectuée selon diverses méthodes: coloration conventionnelle de Giemsa, fl uorochromes chromomycine A3 (CMA3) et 4-6-diamidino-2-phenylindole (DAPI), et mise en evidence de bandes par l'acridine orange. Les ouvrières ont toutes le caryotype 2n=32, avec dix paires de chromosomes métacentriques et six acrocentriques. Un bras chromosomique de la dixième paire s'est montré positif pour le CMA3 et l'acridine orange, suggérant l'existence d'une région organisatrice du nucléole. Cette région est un marqueur spécifi que de choix car elle est très conservatrice et constitue ainsi un intéressant caractère taxonomique. La région péricentromérique de beaucoup de chromosomes a été marquée par le DAPI, mettant en évidence l'existence d'une hétérochromatine riche en bases AT.

Cytogenetic survey of eight ant species from the Amazon rainforest

“…Wasmannia auropunctata Roger (1863) presented 2n = 32, 16m + 10sm + 6st (Figure 3A). Its karyotype showed the same chromosome number and similar morphology to that of the Atlantic rainforest population (Souza et al 2011). Although Souza et al (2011) used a different chromosome classification method (Imai 1991), without the use of chromosome measurements, the karytoype is similar to that obtained in this study, being possible to recognize all chromosome pairs.…”

Cytogenetic data for sixteen ant species from North-eastern Amazonia with phylogenetic insights into three subfamilies

“…It has three different genetic systems: haplodiploidy, male clonality, and thelytoky (Foucaud et al 2006). In this study, the same chromosome number and a similar karyotype from colonies from Ilhéus and Una, southeast Bahia, Brazil were observed (Souza et al 2011), although there are differences in chromosome classification. The heteromorphic pattern was not described for the Atlantic forest population and therefore needs to be investigated further.…”

The First Cytogenetic Data on Strumigenys louisianae Roger, 1863 (Formicidae: Myrmicinae: Dacetini): The Lowest Chromosome Number in the Hymenoptera of the Neotropical Region

“…These regions are considered conserved and found in specific locations for each species. As a result of this specificity, the description of the number and position of this region in the chromosomes can be reliably used in taxonomic and phylogenetic studies [35] .…”

“…2C ). Some species among Hymenoptera present these markings, including some bees [34] , [36] and the little fire ant Wasmannia auropunctata [35] . These markings are mainly present in the centromeric regions [37] , although in W. auropunctata the DAPI rich regions were observed in the pericentromeric region in most chromosomes [35] .…”