Spiroplasma infection in Harmonia axyridis - Diversity and multiple infection.

Irina Goryacheva,Alla Blekhman,Ilya Zakharov,Denis Romanov,Boris Andrianov,Wolfgang Arthofer

doi:10.1371/journal.pone.0198190

Irina Goryacheva, Alla Blekhman + Show 4 more

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https://doi.org/10.1371/journal.pone.0198190

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Journal: PloS one	Publication Date: May 29, 2018
Citations: 14	License type: CC BY 4.0

Affiliation: Russian Academy of Sciences

Abstract

The heritable endosymbiotic bacterium Spiroplasma is found in the harlequin ladybird Harmonia axyridis. The proportion of beetles infected with Spiroplasma in different native H. axyridis populations varies from 2% to 49%. We investigated the polymorphism of Spiroplasma strains in samples from individual beetles from Kyoto, Vladivostok, Troitsa Bay, Novosibirsk, and Gorno-Altaisk. To identify Spiroplasma strains, we analyzed nucleotide polymorphisms of the 16S rRNA gene and the ribosomal internal transcribed spacer (ITS1). The majority of infected beetles were infected with two or more Spiroplasma strains. We measured Spiroplasma density in beetles with different infection status using quantitative PCR. The abundance of Spiroplasma in samples with a single infection is an order of magnitude lower than in samples with multiple infections. Density dependent biological effects of Spiroplasma are discussed.

Highlights

Many insect species are infected with intracellular symbiotic bacteria, which are inherited maternally and affect host reproduction
The ITS1 sequences from G9 and K13 females were identical to the sequence of the Spiroplasma strain HARFUKU2 that was previously found in H. axyridis from Japan (GenBank ID: AB127933) [37]
In most Spiroplasma-infected H. axyridis females from Gorno-Altaisk (G16), Birobidzhan (Bi16, Bi29), Troitsa Bay (T5, T21), Vladivostok (V37, V42), and Kyoto (K11, K15), some nucleotides were ambiguously read at phylogenetically informative sites of both ITS1 and in the fragment of 16S rRNA gene

Summary

Introduction

Many insect species are infected with intracellular symbiotic bacteria, which are inherited maternally and affect host reproduction. Among such bacteria, Wolbachia, Spiroplasma, Rickettsia, and Cardinium are widely known. Spiroplasma is one of the most prevalent and well characterized facultative insect endosymbionts, and it is estimated to infect 5–10% of all insect species [1, 2]. Phylogenetic reconstruction of the genus Spiroplasma using the 16S rRNA gene sequences revealed that the genus comprises four distinct clades: the Ixodetis clade, the Citri-Chrysopicola-Mirum clade, the Apis clade sensu lato, and the Mycoides-Entomoplasmataceae clade [28, 29]

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