Microsatellite and Wolbachia analysis in Rhagoletis cerasi natural populations: population structuring and multiple infections.

Antonios A Augustinos,Nikolaos T Papadopoulos,Cleopatra A Moraiti,Anastasia K Asimakopoulou,Kostas Bourtzis,Penelope Mavragani-Tsipidou

doi:10.1002/ece3.553

Abstract

Rhagoletis cerasi (Diptera: Tephritidae) is a major pest of sweet and sour cherries in Europe and parts of Asia. Despite its economic significance, there is a lack of studies on the genetic structure of R. cerasi populations. Elucidating the genetic structure of insects of economic importance is crucial for developing phenological-predictive models and environmental friendly control methods. All natural populations of R. cerasi have been found to harbor the endosymbiont Wolbachia pipientis, which widely affects multiple biological traits contributing to the evolution of its hosts, and has been suggested as a tool for the biological control of insect pests and disease vectors. In the current study, the analysis of 18 R. cerasi populations collected in Greece, Germany, and Russia using 13 microsatellite markers revealed structuring of R. cerasi natural populations, even at close geographic range. We also analyzed the Wolbachia infection status of these populations using 16S rRNA-, MLST- and wsp-based approaches. All 244 individuals screened were positive for Wolbachia. Our results suggest the fixation of the wCer1 strain in Greece while wCer2, wCer4, wCer5, and probably other uncharacterized strains were also detected in multiply infected individuals. The role of Wolbachia and its potential extended phenotypes needs a thorough investigation in R. cerasi. Our data suggest an involvement of this symbiont in the observed restriction in the gene flow in addition to a number of different ecological factors.

Highlights

The European cherry fruit fly, Rhagoletis cerasi L. (Diptera: Tephritidae) (Fig. 1), is a pest of major agricultural importance infesting mainly sweet (Prunus avium) and sour (P. cerasus) cherries as well as honeysuckle and wild growing prunus
Multivoltine and polyphagous species (Papadopoulos et al 2001), the olive fly is a multivoltine and monophagous species (Tzanakakis 2003), while the cherry fruit fly is a univoltine and stenophagous species (Moraiti et al 2012a,b). These three species differ in their Wolbachia infection status: natural populations of olive fly and medfly are Wolbachia free (Bourtzis et al 1994; Zabalou et al 2004; Apostolaki et al 2011; but see Rocha et al 2005 for an infected Brazilian population) while Wolbachia has been detected in all natural populations of the European cherry fruit fly tested so far
Our results indicate the presence of structuring in natural populations of R. cerasi, which, especially for Greece, is not in accordance with data for the olive fly (Augustinos et al 2005; Zygouridis et al 2009), and the medfly

Summary

Introduction

The European cherry fruit fly, Rhagoletis cerasi L. (Diptera: Tephritidae) (Fig. 1), is a pest of major agricultural importance infesting mainly sweet (Prunus avium) and sour (P. cerasus) cherries as well as honeysuckle (mainly Lonicera tatarica and L. xylosteum) and wild growing prunus. The European cherry fruit fly, Rhagoletis cerasi L. Rhagoletis cerasi has dispersed and become established in almost all European countries, spreading from the original habitat, the Caucasian area of western Asia (Fimiani 1989; White and Elson-Harris 1992). Larvae feed on mesocarp, destroying fruits and causing considerable economic loss exacerbated by secondary fungal and bacterial infections (Fimiani 1989). Because of the economic importance, the control of the European cherry fruit fly received much attention in the framework of the sterile insect technique (SIT) in the early 1970s (Boller et al 1971, 1977; Boller and Katsoyannos 1977)

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Discussion

Conclusion