New Strains of Wolbachia Unveiling the Complexity of This Symbiotic Interaction in Solenopsis (Hymenoptera: Formicidae)

Cintia Martins,Manuela De Oliveira Ramalho,Odair Correa Bueno,Larissa Marin Rodrigues Silva,Rodrigo Fernando De Souza

doi:10.3390/microbiolres12030040

Cintia Martins, Manuela De Oliveira Ramalho + Show 3 more

Open Access

https://doi.org/10.3390/microbiolres12030040

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Abstract

Bacteria of the genus Wolbachia are widely distributed in arthropods, particularly in ants; nevertheless, it is still little explored with the Multilocus Sequence Typing (MLST) methodology, especially in the genus Solenopsis, which includes species native to South America. Ants from this genus have species distributed in a cosmopolitan way with some of them being native to South America. In Brazil, they are widely spread and preferentially associated with areas of human activity. This study aimed to investigate the diversity of Wolbachia in ants of the genus Solenopsis through the MLST approach and their phylogenetic relationship, including the relationship between mtDNA from the host and the related Wolbachia strain. We also tested the geographic correlation between the strains to infer transmission and distributional patterns. Fifteen new strains and eleven previously unknown alleles were obtained by sequencing and analyzing the five genes that make up the MLST. The phylogenetic relationship between the strains showed a polyphyletic pattern, indicative of the complexity of the evolutionary history of these bacteria in the analyzed species. We detected the correlation of host’s mitochondrial DNA with Wolbachia diversity which imply that related strains exist in related hosts, strongly suggesting the occurrence of vertical transfer. We found no specificity of the Wolbachia strain for a given geographic region that could indicate either that there is no horizontal transfer of the strain from the environment for the host or that the human action could be shuffling the distribution of the Solenopsis ants and the endosymbiont Wolbachia, as well. Our study highlights the complexity and novelty of Wolbachia diversity with this specific group of ants and the need for further studies that focus on understanding of this intricate relationship.

Highlights

Wolbachia (Alphaproteobacteria: Rickettsiales) is an endosymbiont widely distributed in insects, and estimates by Zug and Hammerstein [1] indicate that around 40% of arthropods are infected
It is important to note that the previous sequencing of the wsp gene [20] did not detect these multiple infections, since the electropherogram peaks were clearly unique to this gene, and these were only detected with the sequencing of the Multilocus Sequence Typing (MLST) genes, which indicates the ineffectiveness of using a single gene
(COI gene) and Wolbachia diversity, our results indicated a significant correlation (Mantel test, r2 = 0.4476, p = 0.00005), which suggests that related strains exist in related hosts, a strong indication of the occurrence of vertical transfer

Summary

Introduction

Wolbachia (Alphaproteobacteria: Rickettsiales) is an endosymbiont widely distributed in insects, and estimates by Zug and Hammerstein [1] indicate that around 40% of arthropods are infected. In ants, this infection rate is around 34% [2], being indicative of the most prevalent heritable symbiont in ants [3]. Its ability to reproductively alter its hosts has made it the subject of many studies in several insect species. In ants, its performance in reproductive alterations is not yet widely known, especially because of obstacles in such experimental procedures [2]. Few studies have been successful in understanding the effects of Wolbachia on Formicidae, with acceleration of the colony life cycle observed in Monomorium pharaonis and nutritional supplementation of vitamin B detected in Tapinoma melanocephalum in the presence of Wolbachia [4,5].

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