The impacts of temperature and pesticide on the yellow fever mosquito ability to transmit a flavivirus

In humans, flavivirus (Zika virus) infection can cause serious symptoms or be life-threatening, such as microcephaly and Guillain-Barré syndrome. In the absence of effective vaccines, pesticide-based vector control remains the major tool to mitigate the burden of Zika virus infection. The application of pesticides may occur under different environmental temperatures where there is a risk of Zika virus transmission. In this study, we investigated whether traits and ability to transmit Zika virus by the yellow fever mosquito Aedes aegypti can be altered by the interactions between temperatures (20°C and 30°C) and pyriproxyfen during larval stages. Larval development time was prolonged at 20°C and in the presence of pyriproxyfen. Adult emergence inhibition by pyriproxyfen was higher at 30°C than 20°C. Size of females was larger at 20°C than 30°C. Zika virus infection and transmission were enhanced by pyriproxyfen at both 20°C and 30°C. Our data revealed that the interactive effects between temperatures and pesticide can significantly influence mosquito traits and the ability to transmit a flavivirus. The pyriproxyfen-induced enhancement of ZIKV infection in mosquitoes should be a consideration when implementing pyriproxyfen in vector control programs.