The impact of temperature and insect-specific viruses on the transmission of alphaviruses by .

UNLABELLED

Arthropod-borne virus (arbovirus) infections are increasing globally, and invasive mosquito species are spreading. Since the end of the last century, has continued to spread in Europe as well as in North America. is known to be able to transmit several viruses, but extensive information about the vector competence of for alphaviruses is missing. Therefore, we infected field-caught mosquitoes from Germany with different alphaviruses that occur in areas with either tropical or moderate temperatures and are clustered as arthritogenic or encephalitic alphaviruses. Additionally, we studied the influence of temperature and natural infections with insect-specific viruses (ISVs) on the vector competence of . Transmission of chikungunya virus was exclusively observed at the high-temperature profile of 27° ± 5°C, with a low transmission rate of 2.9%. Transmission of Sindbis virus and western equine encephalitis virus was observed at all investigated temperature profiles with higher transmission rates of 32%-57%. We identified seven different ISVs in the investigated mosquitoes, showing that coinfections with ISVs are very common. The interplay between arbovirus infections and concurrent multiple ISV infections is highly complex, and additional research is required to fully elucidate the detailed mechanisms underlying the outcomes of this study.

IMPORTANCE

The spread of invasive mosquito species like poses a significant public health risk, particularly in the context of rising global temperatures and the growing prevalence of arbovirus infections. This study provides critical insights into the ability of to transmit alphaviruses such as chikungunya, Sindbis, and western equine encephalitis under different temperature conditions. The identification of multiple insect-specific viruses co-infecting the mosquitoes highlights the complexity of arbovirus transmission and underscores the need for further research. Understanding the interplay between environmental factors like temperature and viral coinfections is essential for predicting and mitigating future outbreaks. This work advances our knowledge of vector competence, which is helpful for developing strategies for risk assessment.