Cytogenetic Analysis of the South American Fruit Fly Anastrepha fraterculus (Diptera:Tephritidae) Species Complex: Construction of Detailed Photographic Polytene Chromosome Maps of the Argentinian Af. sp.1 Member.

Angeliki Gariou-Papalexiou,Carlos Caceres,Elena Drosopoulou,Antigone Zacharopoulou,Penelope Mavragani-Tsipidou,Jorge L Cladera,María Cecilia Giardini,Antonios A Augustinos,Kostas Bourtzis,Silvia B Lanzavecchia,Igor V Sharakhov

doi:10.1371/journal.pone.0157192

Abstract

Genetic and cytogenetic studies constitute a significant basis for understanding the biology of insect pests and the design and the construction of genetic tools for biological control strategies. Anastrepha fraterculus is an important pest of the Tephritidae family. It is distributed from southern Texas through eastern Mexico, Central America and South America causing significant crop damage and economic losses. Currently it is considered as a species complex; until now seven members have been described based on multidisciplinary approaches. Here we report the cytogenetic analysis of an Argentinian population characterized as Af. sp.1 member of the Anastrepha fraterculus species complex. The mitotic karyotype and the first detailed photographic maps of the salivary gland polytene chromosomes are presented. The mitotic metaphase complement consists of six (6) pairs of chromosomes, including one pair of heteromorphic sex chromosomes, with the male being the heterogametic sex. The analysis of the salivary gland polytene complement shows a total number of five long chromosomes that correspond to the five autosomes of the mitotic karyotype and a heterochromatic network corresponding to the sex chromosomes. Comparison of the polytene chromosome maps between this species and Anastrepha ludens shows significant similarity. The polytene maps presented here are suitable for cytogenetic studies that could shed light on the species limits within this species complex and support the development of genetic tools for sterile insect technique (SIT) applications.

Highlights

Cytogenetic analysis of Diptera species has been greatly facilitated by the existence of polytene chromosomes
Two of the autosomes are longer and are distinguished from the rest, which are more or less of similar size. Both sex chromosomes are highly heterochromatic as shown following Giemsa (Fig 1A, 1B and 1C) and C-banding staining (Fig 1D and 1E), in accordance with previous studies based on Giemsa staining and C banding [57,66]
The sex chromosomes are labeled as the first pair of the mitotic karyotype and the autosomes from 2–6 in order of descending size

Summary

Introduction

Cytogenetic analysis of Diptera species has been greatly facilitated by the existence of polytene chromosomes. Since the first publication of the chromosome maps of Drosophila [1], polytene chromosomes have proven to be an excellent genetic tool for studying chromosome structure and function, gene activity, phylogenetic relationships and have served as diagnostic tools for distinguishing members of species complexes [2,3,4,5,6,7,8]. They provide means for detailed cytogenetic maps through the precise mapping by in situ hybridization [9]. Cytogenetic analysis of mitotic and polytene chromosome maps have helped the analysis of GSSs in other tephritid species, such as Bactrocera dorsalis, B. cucurbitae [15] and Anastrepha ludens [16]

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Discussion

Conclusion