Aedes aegypti mosquitoes infected with the
wMel strain of
Wolbachia are being deployed to control the spread of arboviruses around the world through blockage of viral transmission. Blockage by
Wolbachia in some scenarios may be affected by the susceptibility of
wMel
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Aedes aegypti mosquitoes infected with the
wMel strain of
Wolbachia are being deployed to control the spread of arboviruses around the world through blockage of viral transmission. Blockage by
Wolbachia in some scenarios may be affected by the susceptibility of
wMel to cyclical heat stress during mosquito larval development. We therefore evaluated the potential to generate a heat-resistant strain of
wMel in
Ae. aegypti through artificial laboratory selection and through exposure to field temperatures across multiple generations. To generate an artificially selected strain,
wMel-infected females reared under cyclical heat stress were crossed to
wMel-infected males reared at 26 °C. The low proportion of larvae that hatched founded the next generation, and this process was repeated for eight generations. The
wMel heat-selected strain (
wMel-HS) was similar to
wMel (unselected) in its ability to induce cytoplasmic incompatibility and restore compatibility when larvae were reared under cyclical heat stress, but
wMel-HS adults exhibited reduced
Wolbachia densities at 26 °C. To investigate the effects of field exposure, we compared the response of
wMel-infected
Ae. aegypti collected from Cairns, Australia where the infection has been established for seven years, to a
wMel-infected population maintained in the laboratory for approximately 60 generations. Field and laboratory strains of
wMel did not differ in their response to cyclical heat stress or in their phenotypic effects at 26 °C. The capacity for the
wMel infection in
Ae. aegypti to adapt to high temperatures therefore appears limited, and alternative strains may need to be considered for deployment in environments where high temperatures are regularly experienced in mosquito breeding sites.
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