SARS-CoV-2 failure to infect or replicate in mosquitoes: an extreme challenge



This research addresses public speculation that SARS-CoV-2 might be transmitted by mosquitoes. The World Health Organization has stated “To date there has been no information nor evidence to suggest that the new coronavirus could be transmitted by mosquitoes”. Here we provide the first experimental data to investigate the capacity of SARS-CoV-2 to infect and be transmitted by mosquitoes. Three widely distributed species of mosquito; Aedes aegypti, Ae. albopictus and Culex quinquefasciatus, representing the two most significant genera of arbovirus vectors that infect people, were tested. We demonstrate that even under extreme conditions, SARS-CoV-2 virus is unable to replicate in these mosquitoes and therefore cannot be transmitted to people even in the unlikely event that a mosquito fed upon a viremic host.


The question has been asked as to whether or not SARS-CoV-2, the causative agent of COVID-19, can infect and be transmitted by mosquitoes. The WHO has definitively stated that mosquitoes cannot transmit the virus1, and in interviews, various experts have unanimously and definitively also dispelled the suggestion that SARS-CoV-2 could be transmitted by mosquitoes. The presumption may be based on various observations and facts extrapolated from other coronaviruses. For example, neither the closely related SARS-CoV nor MERS produce the level of virus in the blood that for typical arthropod-borne viruses such as dengue and yellow fever, would be regarded as high enough to infect mosquitoes. Recent studies with infected humans and non-human primates infected with SARS-CoV-2, found no detectable virus in peripheral blood2,3. Lack of viremia is also suggested by the fact that neither SARS-CoV nor MERS infections have resulted from blood transfusions or organ transplantations. Since mechanical transmission of viruses by arthropods requires a very high viremia4, even if mosquitoes were interrupted when feeding on a SARS-CoV-2 infected person, the mouthparts would not be contaminated. Although we do not know the duration of virus infectivity on contaminated surfaces, mechanical transmission by non-hematophagous arthropods seems highly unlikely, and even if not impossible, would result in very few, if any human infections, and not be epidemiologically relevant. Despite the lack of detectable viremia, experiments to determine the potential role of mosquitoes in SARS-CoV-2 transmission, are necessary because previous experiments have demonstrated that mosquitoes may become infected with viruses even when exposed to levels of infectious virus that are below the level of detection5,6,7.

To be a biological vector of viruses, mosquitoes must take up sufficient virus to infect midgut epithelial cells, and the virus must then disseminate to infect other organs in the hemocoel, notably the salivary glands. Overcoming the midgut infection and escape barriers is essential for a virus to be transmissible by mosquitoes. If these barriers are bypassed by direct inoculation of virus into the hemocoel, then even non-susceptible mosquitoes can be infected. Intrathoracic inoculation8,9 of virus directly into the hemocoel can accomplish short-term infection of insects that could never be naturally infected because they do not feed on blood. These include not only non-hematophagous mosquitoes such as Toxorhynchites spp, but also male mosquitoes and even beetles and butterflies10,11. The use of intrathoracic inoculation, also addressed published reports that the natural physical breaching of the midgut wall by filarial, may enable a disseminated coinfection of viruses in resistant mosquitoes12.

Similar to over 500 viruses that are transmitted by arthropods13, with the exception of African swine fever virus, coronaviruses have an RNA genome. In spite of the recovery of coronavirus or coronavirus-like agents from various arthropods14,15, no virus in the family has been isolated from mosquitoes. To date, only one report related to epidemic coronaviruses and mosquitoes has been published16. This study that evaluated the potential use of mosquitoes for surveillance, included feeding of MERS virus to Anopheles gambiae mosquitoes. Residual viral RNA, probably in the remains of the bloodmeal in the midgut, was detected up to 1-day post-feeding. Similarly, positive PCR detection was observed for Bacillus anthracis, Trypanosoma brucei gambiensis, and Zika virus, none of which infect or are transmitted by An. gambiae. Levels of detected RNA were equal to or below the input level, indicating a lack of replication. By analyzing samples using in vitro cultivation, rather than using molecular approaches, we focused specifically on detection of infectious virus rather than on RNA. As illustrated by, for example, the use of inactivation techniques specifically developed to enable safe handling and shipping of viral material, the mere presence of RNA does not mean that any infectious virus is actually present. It is well known that viral RNA can be detected in mosquitoes simply because they have fed on a viremic host, and so RNA detection should never be interpreted as proof of mosquito susceptibility to infection and competence to transmit the virus.


In this study, the susceptibility of three mosquito species, Ae. aegypti, Ae. albopictus and Cx. quinquefasciatus, were determined through the intrathoracic inoculation with SARS-CoV-2. Infectious viruses were recovered from 13/15 mosquitoes collected within two hours of inoculation. It is possible, that in the two negative mosquitoes, the inoculated virus lost infectivity during the holding period. No virus was detected in the 277 inoculated mosquitoes collected and titrated at time points beyond 24 h, suggesting a rapid loss of infectivity and the lack of replication after injection. From a total of 48 mosquitoes analyzed, infectious viruses were only recovered from one Ae. albopictus collected at 24 h post-inoculation. The quantity of infectious virus in this mosquito corresponded to the amount of inocula, producing infectious titers at approximately 1.5 logTCID50/ml. No virus was detected in control L-15 medium inoculated mosquitoes. Collectively, our findings suggest that mosquitoes in the Aedes and Culex genera are refractory to SARS-CoV-2 and unlikely to contribute to viral maintenance and transmission in nature (Table 1.).

Table 1 Recovery rates of SARS-CoV-2 in mosquitoes receiving intrathoracic injection.


The most extreme approach for viral challenge of mosquitoes, namely intrathoracic inoculation, was used as an ultimate test of the capacity of SARS-CoV-2 to infect and replicate in mosquitoes. The hypothesis was that if the virus did not replicate in mosquitoes after intrathoracic inoculation, then even if mosquitoes did feed on viremic people, and the virus disseminated from the midgut, the lack of replication would preclude the possibility of biological transmission. Three widely distributed species of mosquito, representing the two most significant genera of arbovirus vectors that infect people, were tested. All three of the species: Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus are present in China, the country of origin of SARS-CoV-2. Samples collected within two hours of inoculation confirmed efficient delivery of infectious viruses to mosquitoes. Based upon the lack of detectable infectious virus in any of the 277 samples collected at all time points beyond 24 h post-inoculation, we conclude that SARS-CoV-2 is unable to replicate in mosquitoes and that even if a mosquito fed on a person with virus in the blood, that the mosquito would not be a vector if feeding on a naïve host.


Virus: SARS-CoV-2 virus WA1/2020 strain was obtained from BEI Resources (Catalog # NR-52281). Virus was propagated in Vero76 cells at the approximate multiplicity of infection of 0.01. Using serial tenfold dilutions in 96-well plates17, infectious titers of viral stocks used for intrathoracic injection were approximately 5.5 logTCID50/ml.

Mosquitoes: The colonized Aedes aegypti strain Rex D, Higgs white eye was originally obtained from Puerto Rico18, Ae. albopictus generation F11 originated from New Jersey, and Culex quinquefasciatus F43 were from Florida19,20. All mosquitoes were reared at 28 °C, relative humidity of 80% and a 12 h light:12 h dark photoperiod. These colonized mosquitoes have proven to be susceptible to several arboviruses19,21,22,23,24,25,26.

Viral challenge of mosquitoes: For intrathoracic inoculation9, mosquitoes were cold-anaesthetized on ice, transferred to a secure glove box, and then inoculated with approximately 0.5 µl of viral stock. It was anticipated that each mosquito received approximately 2.0 logTCID50/ml of infectious viruses. L-15 medium was inoculated as a negative control. The results were compiled from two experiments using Ae. aegypti and Ae. albopictus and one experiment using Cx. quinquefasciatus. Experimentally challenged mosquitoes were maintained and sampled under conditions as described above. Mosquitoes were individually triturated in 1 ml of medium using a TissueLyser II platform (Qiagen, Valencia, CA), and titrated on Vero cells as previously described.


  1. 1.

    World Health Organization. Coronavirus disease (COVID-19) advice for the public: Myth busters 2020 [cited 2020 2020/05/22]. Available from:

  2. 2.

    Chandrashekar, A., Liu, J., Martinot, A. J., McMahan, K., Mercado, N, B,, Peter, L. et al. SARS-CoV-2 infection protects against rechallenge in rhesus macaques. Science (2020).

  3. 3.

    Huang, C. et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet 395(10223), 497–506 (2020).

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  4. 4.

    Turell, M. J., Dohm, D. J., Geden, C. J., Hogsette, J. A. & Linthicum, K. J. Potential for stable flies and house flies (Diptera: Muscidae) to transmit Rift Valley fever virus. J. Am. Mosq. Control Assoc. 26(4), 445–448 (2010).

    PubMed  Article  Google Scholar 

  5. 5.

    Higgs, S., Schneider, B. S., Vanlandingham, D. L., Klingler, K. A. & Gould, E. A. Nonviremic transmission of West Nile virus. Proc. Natl. Acad. Sci. USA. 102(25), 8871–8874 (2005).

    ADS  CAS  PubMed  Article  Google Scholar 

  6. 6.

    McGee, C. E., Schneider, B. S., Girard, Y. A., Vanlandingham, D. L. & Higgs, S. Nonviremic transmission of West Nile virus: evaluation of the effects of space, time, and mosquito species. Am. J. Trop. Med .Hyg. 76(3), 424–430 (2007).

    PubMed  Article  Google Scholar 

  7. 7.

    Reisen, W. K., Fang, Y. & Martinez, V. Is nonviremic transmission of West Nile virus by Culex mosquitoes (Diptera: Culicidae) nonviremic?. J. Med. Entomol. 44(2), 299–302 (2007).

    PubMed  Article  Google Scholar 

  8. 8.

    Rosen, L. The use of Toxorhynchites mosquitoes to detect and propagate dengue and other arboviruses. Am. J. Trop. Med. Hyg. 30(1), 177–183 (1981).

    CAS  PubMed  Article  Google Scholar 

  9. 9.

    Rosen, L. & Gubler, D. The use of mosquitoes to detect and propagate dengue viruses. Am. J. Trop. Med. Hyg. 23(6), 1153–1160 (1974).

    CAS  PubMed  Article  Google Scholar 

  10. 10.

    Peloquin, J. J., Thomas, T. A. & Higgs, S. Pink bollworm larvae infection with a double subgenomic Sindbis (dsSIN) virus to express genes of interest. J. Cotton Sci. 5(2), 114–120 (2001).

    CAS  Google Scholar 

  11. 11.

    Lewis, D. L. et al. Ectopic gene expression and homeotic transformations in arthropods using recombinant Sindbis viruses. Curr. Biol. 9(22), 1279–1287 (1999).

    CAS  PubMed  Article  Google Scholar 

  12. 12.

    Vaughan, J. A., Trpis, M. & Turell, M. J. Brugia malayi microfilariae (Nematoda: Filaridae) enhance the infectivity of Venezuelan equine encephalitis virus to Aedes mosquitoes (Diptera: Culicidae). J. Med. Entomol. 36(6), 758–763 (1999).

    CAS  PubMed  Article  Google Scholar 

  13. 13.

    Centers for Disease Control and Prevention. International Catalog of Arboviruses. In: Prevention CfDCa, editor. Atlanta, GA: Center for Disease Control and Prevention; 1985.

  14. 14.

    Traavik, T., Mehl, R. & Kjeldsberg, E. “Runde” virus, a coronavirus-like agent associated with seabirds and ticks. Arch. Virol. 55(1–2), 25–38 (1977).

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  15. 15.

    Calibeo-Hayes, D. et al. Mechanical transmission of turkey coronavirus by domestic houseflies (Musca domestica Linnaeaus). Avian Dis. 47(1), 149–153 (2003).

    PubMed  Article  Google Scholar 

  16. 16.

    Fauver, J. R. et al. The use of xenosurveillance to detect human bacteria, parasites, and viruses in mosquito bloodmeals. Am. J. Trop. Med. Hyg. 97(2), 324–329 (2017).

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  17. 17.

    Higgs, S. et al. Growth characteristics of ChimeriVax-Den vaccine viruses in Aedes aegypti and Aedes albopictus from Thailand. Am. J. Trop. Med. Hyg. 75(5), 986–993 (2006).

    PubMed  Article  Google Scholar 

  18. 18.

    Wendell, M. D., Wilson, T. G., Higgs, S. & Black, W. C. Chemical and gamma-ray mutagenesis of the white gene in Aedes aegypti. Insect Mol. Biol. 9(2), 119–125 (2000).

    CAS  PubMed  Article  Google Scholar 

  19. 19.

    Park, S. L., Huang, Y. S., Higgs, S. & Vanlandingham, D. L. Application of a nonpaper based matrix to preserve chikungunya virus infectivity at ambient temperature. Vector Borne Zoo. Dis. 18(5), 278–281 (2018).

    Article  Google Scholar 

  20. 20.

    Huang, Y. J. et al. Culex species mosquitoes and Zika virus. Vector Borne Zoo. Dis. 16(10), 673–676 (2016).

    Article  Google Scholar 

  21. 21.

    Huang, Y. S. et al. Differential outcomes of Zika virus infection in Aedes aegypti orally challenged with infectious blood meals and infectious protein meals. PLoS ONE 12(8), e0182386 (2017).

    PubMed  PubMed Central  Article  Google Scholar 

  22. 22.

    Ayers, V. B. et al. Culex tarsalis is a competent vector species for Cache Valley virus. Parasit. Vectors. 11(1), 519 (2018).

    PubMed  PubMed Central  Article  Google Scholar 

  23. 23.

    Ayers, V. B. et al. Infection and transmission of Cache Valley virus by Aedes albopictus and Aedes aegypti mosquitoes. Parasit. Vectors. 12(1), 384 (2019).

    PubMed  PubMed Central  Article  Google Scholar 

  24. 24.

    Tsetsarkin, K. A., Vanlandingham, D. L., McGee, C. E. & Higgs, S. A single mutation in chikungunya virus affects vector specificity and epidemic potential. PLoS Pathog. 3(12), e201 (2007).

    PubMed  PubMed Central  Article  Google Scholar 

  25. 25.

    Nuckols, J. T. et al. Evaluation of simultaneous transmission of chikungunya virus and dengue virus type 2 in infected Aedes aegypti and Aedes albopictus (Diptera: Culicidae). J. Med. Entomol. 52(3), 447–451 (2015).

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  26. 26.

    Cook, C. L. et al. North American Culex pipiens and Culex quinquefasciatus are competent vectors for Usutu virus. PLoS Negl. Trop. Dis. 12(8), e0006732 (2018).

    PubMed  PubMed Central  Article  Google Scholar 

Download references


This work was performed in the ACL-3 insectary at Kansas State University’s Biosecurity Research Institute. The research was in part supported by the State of Kansas National Bio and Agro-defense Facility (NBAF) Transition Fund.

Author information




S.H., D.L.V., and Y.S.H. conceived the study. Y.S.H., A.B., H.M.S., and S.H. executed the experimental plans. D.L.V. provided financial support and reviewed the manuscript. S.M.H. prepared approvals for the research, coordinated experiments, and prepared manuscript. All authors reviewed the manuscript.

Corresponding author

Correspondence to Stephen Higgs.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher's note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Huang, Y.S., Vanlandingham, D.L., Bilyeu, A.N. et al. SARS-CoV-2 failure to infect or replicate in mosquitoes: an extreme challenge. Sci Rep 10, 11915 (2020).

Download citation


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Sign up for the Nature Briefing newsletter for a daily update on COVID-19 science.
Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing