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This article is part of the supplement: Arthropod symbioses: from fundamental studies to pest and disease management

Open Access Research

Microbial community of predatory bugs of the genus Macrolophus (Hemiptera: Miridae)

Thijs Machtelinckx1, Thomas Van Leeuwen1, Tom Van De Wiele2, Nico Boon2, Winnok H De Vos34, Juan-Antonio Sanchez5, Mauro Nannini6, Godelieve Gheysen7 and Patrick De Clercq1*

Author Affiliations

1 Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium

2 Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Gent, Belgium

3 Laboratory of Bio-imaging and Cytometry, Department of Molecular Biotechnology, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium

4 Center for Nano- and Biophotonics (NB-Photonics), Ghent University, Gent, Belgium

5 Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), Departamento de Biotecnología y Protección de Cultivos, La Alberca, Murcia, Spain

6 AGRIS Sardegna - DIRVE, Cagliari, Italy

7 Laboratory of Applied Molecular Genetics, Department of Molecular Biotechnology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium

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BMC Microbiology 2012, 12(Suppl 1):S9  doi:10.1186/1471-2180-12-S1-S9

Published: 18 January 2012

Abstract

Background

The predatory mirids of the genus Macrolophus are key natural enemies of various economically important agricultural pests. Both M. caliginosus and M. pygmaeus are commercially available for the augmentative biological control of arthropod pests in European greenhouses. The latter species is known to be infected with Wolbachia -inducing cytoplasmic incompatibility in its host- but the presence of other endosymbionts has not been demonstrated. In the present study, the microbial diversity was examined in various populations of M. caliginosus and M. pygmaeus by 16S rRNA sequencing and denaturing gradient gel electrophoresis.

Results

Besides Wolbachia, a co-infection of 2 Rickettsia species was detected in all M. pygmaeus populations. Based on a concatenated alignment of the 16S rRNA gene, the gltA gene and the coxA gene, the first is phylogenetically related to Rickettsia bellii, whereas the other is closely related to Rickettsia limoniae. All M. caliginosus populations were infected with the same Wolbachia and limoniae-like Rickettsia strain as M. pygmaeus, but did not harbour the bellii-like Rickettsia strain. Interestingly, individuals with a single infection were not found. A PCR assay on the ovaries of M. pygmaeus and M. caliginosus indicated that all endosymbionts are vertically transmitted. The presence of Wolbachia and Rickettsia in oocytes was confirmed by a fluorescence in situ hybridisation. A bio-assay comparing an infected and an uninfected M. pygmaeus population suggested that the endosymbionts had minor effects on nymphal development of their insect host and did not influence its fecundity.

Conclusion

Two species of the palaearctic mirid genus Macrolophus are infected with multiple endosymbionts, including Wolbachia and Rickettsia. Independent of the origin, all tested populations of both M. pygmaeus and M. caliginosus were infected with three and two endosymbionts, respectively. There was no indication that infection with endosymbiotic bacteria had a fitness cost in terms of development and fecundity of the predators.