Does membrane feeding compromise the quality of Aedes aegypti mosquitoes?

Abstract

Modified Aedes aegypti mosquitoes are being mass-reared for release in disease control programs around the world. Releases involving female mosquitoes rely on them being able to seek and feed on human hosts. To facilitate the mass-production of mosquitoes for releases, females are often provided blood through artificial membrane feeders. When reared across generations there is a risk that mosquitoes will adapt to feeding on membranes and lose their ability to feed on human hosts. To test adaptation to membrane feeding, we selected replicate populations of Ae. aegypti for feeding on either human arms or membrane feeders for at least 8 generations. Membrane-selected populations suffered fitness costs, likely due to inbreeding depression arising from bottlenecks. Membrane-selected females had higher feeding rates on membranes than human-selected ones, suggesting adaptation to membrane feeding, but they maintained their attraction to host cues and feeding ability on humans despite a lack of selection for these traits. Host-seeking ability in small laboratory cages did not differ between populations selected on the two blood sources, but membrane-selected females were compromised in a semi-field enclosure where host-seeking was tested over a longer distance. Our findings suggest that Ae. aegypti may adapt to feeding on blood provided artificially, but this will not substantially compromise field performance or affect experimental assessments of mosquito fitness. However, large population sizes during mass rearing with membrane feeders should be maintained to avoid bottlenecks which lead to inbreeding depression.\n\nAuthor summaryWith modified mosquitoes being mass-reared for release in disease control programs, there is interest in understanding factors that can affect the quality of release stocks. In the laboratory, membrane feeding devices are often used to provide blood to female mosquitoes which they need to lay eggs. Over time, mosquitoes could adapt to membrane feeding and lose their preference for (or ability to feed on) natural hosts. Adaptation could affect the performance of lab-reared mosquitoes when deployed in the field, especially if the success of disease control programs relies on female reproduction such as in gene drive or Wolbachia-based approaches. We tested to see if Aedes aegypti mosquitoes, the principal vectors of dengue virus, would adapt to feeding on blood provided via membranes. We found some evidence of adaptation, with membrane-selected mosquitoes having higher feeding rates on membranes, but this didnt affect their ability to feed on humans or their attraction to host cues. Although membrane feeding alone does not substantially affect mosquito quality, it can lead to inbreeding depression if populations pass through bottlenecks as they adapt to feeding on blood provided artificially. Our results may inform mass-rearing programs involving the release of modified female mosquitoes.