Microbiota and transcriptome changes of Culex pipiens pallens larvae exposed to Bacillus thuringiensis israelensis

Ruiling Zhang,Xinyu Zhang,Zhong Zhang,Wenjuan Liu,Qian Zhang

doi:10.1038/s41598-021-99733-8

Ruiling Zhang, Xinyu Zhang + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-99733-8

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Abstract

Culex pipiens pallens is an important vector of lymphatic filariasis and epidemic encephalitis. Mosquito control is the main strategy used for the prevention of mosquito-borne diseases. Bacillus thuringiensis israelensis (Bti) is an entomopathogenic bacterium widely used in mosquito control. In this study, we profiled the microbiota and transcriptional response of the larvae of Cx. pipiens pallens exposed to different concentrations of Bti. The results demonstrated that Bti induced a significant effect on both the microbiota and gene expression of Cx. pipiens pallens. Compared to the control group, the predominant bacteria changed from Actinobacteria to Firmicutes, and with increase in the concentration of Bti, the abundance of Actinobacteria was gradually reduced. Similar changes were also detected at the genus level, where Bacillus replaced Microbacterium, becoming the predominant genus in Bti-exposed groups. Furthermore, alpha diversity analysis indicated that Bti exposure changed the diversity of the microbota, possibly because the dysbiosis caused by the Bti infection inhibits some bacteria and provides opportunities to other opportunistic taxa. Pathway analysis revealed significant enhancement for processes associated with sphingolipid metabolism, glutathione metabolism and glycerophospholipid metabolism between all Bti-exposed groups and control group. Additionally, genes associated with the Toll and Imd signaling pathway were found to be notably upregulated. Bti infection significantly changed the bacterial community of larvae of Cx. pipiens pallens.

Highlights

Culex pipiens pallens is an important vector of lymphatic filariasis and epidemic encephalitis
In the present study, which is based on the 16S rRNA gene and RNA sequencing (RNA-Seq), we explored the dynamic changes in the microbiota of Cx. pipiens pallens that are exposed to different Bacillus thuringiensis israelensis (Bti) concentrations and identified the differentially expressed genes triggered by the Bti infection
Firmicutes was the dominant phylum of mosquito samples exposed to Bti, while the predominant phylum in the control groups was Actinobacteria (Fig. 2)

Summary

Introduction

Culex pipiens pallens is an important vector of lymphatic filariasis and epidemic encephalitis. Bacillus thuringiensis israelensis (Bti) is an entomopathogenic bacterium widely used in mosquito control. Due to the lack of effective vaccines and increasing drug resistance in pathogens, vector control is an important tool for the prevention of major mosquito-borne diseases worldwide[9,10]. Differentially expressed genes and molecular pathways induced by Bti infection might contribute to better understanding of the molecular regulation of the mosquito response to Bti and help in evaluating potential targets for molecular-based vector control. In the present study, which is based on the 16S rRNA gene and RNA sequencing (RNA-Seq), we explored the dynamic changes in the microbiota of Cx. pipiens pallens that are exposed to different Bti concentrations and identified the differentially expressed genes triggered by the Bti infection

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