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Published on: May 24, 2020
Culex torrentium mosquitoes from Germany are negative for Wolbachia
M Leggewie1, R Krumkamp2,3, M Badusche1
1Molecular Entomology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
Abstract:
Wolbachia (Rickettsiales: Anaplasmataceae) infects a wide range of arthropods, including several mosquito species. The bacterium is known to induce a plethora of phenotypes in its host, examples being the reproductive phenotype cytoplasmic incompatibility or resistance against infection with arboviruses. The latter is especially relevant when assessing the vector competence of mosquito species for emerging arboviruses. Thus, knowledge of Wolbachia infection status is important for the assessment of vector competence. To facilitate Wolbachia screening in mosquito populations, a quantitative polymerase chain reaction (qPCR) assay was developed to enable high-throughput analysis of mosquito samples. Using this assay, the Wolbachia infection status of the two most common Culex mosquito species in Germany, Culex pipiens biotype pipiens Linnaeus (Diptera: Culicidae) and Culex torrentium Martini (Diptera: Culicidae), was assessed. About 93% of all tested C. pipiens biotype pipiens individuals were positive for Wolbachia, whereas none of the C. torrentium samples was found to be infected. Furthermore, other applications of the qPCR assay were explored by assessing a potential link between the levels of Wolbachia and West Nile virus (WNV) infections in German C. pipiens biotype pipiens mosquitoes. No relationship was found between the two variables, indicating that a Wolbachia-induced antiviral phenotype in this mosquito population is not exclusively attributable to the general level of bacterial infection.
Insights
A new qPCR assay efficiently screens mosquitoes for Wolbachia bacteria. This study found Wolbachia prevalent in Culex pipiens but absent in Culex torrentium, impacting arbovirus vector competence assessments.
Area of Science:
- Microbiology
- Vector-borne diseases
- Molecular biology
Background:
- Wolbachia bacteria are widespread in arthropods, influencing host reproduction and immunity.
- Wolbachia's ability to confer arbovirus resistance is crucial for evaluating mosquito vector competence.
- Assessing Wolbachia infection status in mosquito populations is vital for public health.
Purpose of the Study:
- To develop a high-throughput quantitative polymerase chain reaction (qPCR) assay for Wolbachia screening in mosquitoes.
- To determine the Wolbachia infection prevalence in two common German Culex mosquito species: Culex pipiens and Culex torrentium.
- To investigate the correlation between Wolbachia levels and West Nile virus (WNV) infection in Culex pipiens.
Main Methods:
- Development and application of a novel qPCR assay for high-throughput Wolbachia detection.
- Screening of field-collected Culex pipiens biotype pipiens and Culex torrentium mosquitoes from Germany.
- Analysis of potential links between Wolbachia bacterial load and WNV infection intensity.
Main Results:
- The developed qPCR assay enabled efficient, high-throughput screening of mosquito samples.
- Approximately 93% of Culex pipiens biotype pipiens individuals tested positive for Wolbachia.
- No Wolbachia infection was detected in any of the tested Culex torrentium samples.
- No significant correlation was found between Wolbachia levels and West Nile virus infection in Culex pipiens.
Conclusions:
- The qPCR assay is a valuable tool for rapid Wolbachia screening in mosquito populations.
- Culex pipiens biotype pipiens in Germany is highly infected with Wolbachia, while Culex torrentium is not.
- The absence of a correlation suggests that Wolbachia-mediated antiviral effects in this population are not solely dependent on bacterial load.
