Cytogenetic analysis of the Ethiopian fruit fly Dacus ciliatus (Diptera: Tephritidae)

Abstract

The Ethiopian fruit fly, Dacus ciliatus, is an important pest of cucurbits, which recently invaded the Middle East. The genetics and cytogenetics of D. ciliatus have been scarcely studied. Such information is, however, an essential basis for understanding the biology of insect pests, as well as for the design of modern control strategies. We report here the mitotic karyotype and detailed photographic maps of the salivary gland polytene chromosomes of this species. The mitotic metaphase complement consists of six pairs of chromosomes, including one pair of heteromorphic sex (XX/XY) chromosomes. The heterogametic sex is ascribed to the male. The analysis of the salivary gland polytene complement shows a total number of five long chromosomes (10 polytene arms), which correspond to the five autosomes of the mitotic nuclei, and a heterochromatic mass corresponding to the sex chromosomes. Banding patterns, as well as the most characteristic features and prominent landmarks of each polytene chromosome are presented and discussed. Chromosomal homologies between D. ciliatus and Bactrocera oleae are proposed by comparing chromosome banding patterns and by in situ hybridization of the hsp70 gene.

Genetic and cytogenetic analysis of the American cherry fruit fly, Rhagoletis cingulata (Diptera: Tephritidae)

“…1). This karyotype is consistent with the modal number of chromosomes of most Tephritidae species analyzed so far (Singh and Gupta 1984;Bedo 1986;Zacharopoulou 1987;Mavragani-Tsipidou et al 1992;Hunwattanakul and Baimai 1994;Baimai et al 1995Baimai et al , 1996Baimai et al , 2000Selivon and Perondini 1997;Zhao et al 1998;Shahjahan and Yesmin 2002;Cevallos and Nation 2004;Selivon et al 2005;Garcia-Martinez et al 2009;Drosopoulou et al 2010Drosopoulou et al , 2011Zacharopoulou et al 2011a, b). Most Rhagoletis species, such as R. pomonella, R. berberidis, R. nova, R. conversa, R. brincidi, R. cerasi and R. completa (Bush 1966;Bush and Boller 1977;Procunier and Smith 1993;Frias 2002; Kounatidis et al ?…”

“…This observation is comparable with the situation in R. completa, where the sex chromosomes are also of equal size (Drosopoulou et al 2010). The correspondence of the heterochromatic network of the polytene nuclei to the sex chromosomes of the mitotic complement has also been proposed for other Diptera (Childress 1969;Bedo 1982Bedo , 1987Bedo and Zacharopoulou 1988;Mavragani-Tsipidou et al 1992;Shahjahan and Yesmin 2002;Kounatidis et al 2008;Drosopoulou et al 2010Drosopoulou et al , 2011. Further analysis of X-linked sequences and the localization by in situ hybridization of genes in both mitotic and polytene chromosomes will be needed in order to establish correlations between the two sets of chromosomal elements (mitotic and polytene) and to provide information on the fate of the sex chromosomes of the mitotic complements.…”

“…2d), complicating the identification of the individual chromosomes. The absence of a typical chromocenter (as an accumulation of the heterochromatic centromeric masses of all chromosomes) is also the case observed in most tephritids studied so far (Foster 1980;Bedo 1986;Zacharopoulou 1987Zacharopoulou , 1990Mavragani-Tsipidou et al 1992;Shahjahan and Yesmin 2002;Kounatidis et al 2008;Drosopoulou et al 2010Drosopoulou et al , 2011, with the exception of B. tryoni, where a partial chromocenter was reported (Zhao et al 1998). The R. cingulata polytene complement consists of a total of five long chromosomes with two arms each.…”

“…A prerequisite for the development of such techniques is the mapping of the current Wolbachia infection status of the pest species to be targeted. Moreover, recent cytogenetic and genetic studies on several Tephritidae species correlate the presence of Wolbachia infections with the phenomenon of asynapsis observed in their polytene chromosomes (Kounatidis et al 2008;Drosopoulou et al 2010Drosopoulou et al , 2011.…”

“…However, for another Rhagoletis species, R. pomonela, it was proposed that the largest pair of chromosomes of the mitotic complement corresponds to the sex chromosomes (Procunier and Smith 1993). Dot-shaped appearance of the sex chromosomes has been also reported in some other Tephritid species (Baimai et al 1996;Drosopoulou et al 2011).…”