Considerations for male fitness in successful genetic vector control programs

Abstract

A number of genetic control strategies, including sterile, transgenic, and Wolbachia-based approaches, are under development to reduce mosquito vector populations and the impact of important diseases such as malaria and dengue. Fitness of released males is critically important for the success of these strategies. In order to understand how to optimise the success of released males, we need to determine how males behave in their natural environment and which factors contribute to their success. Male mosquito biology has received little attention, although recent contributions have advanced our knowledge in this area. These advances include the discovery of precopulatory acoustic interactions and the identification of seminal fluid proteins that may have profound effects on female physiology and behaviour. Gaps in our knowledge include detailed information on male survival, dispersal, and mating strategies in the field across a range of geographical and ecological settings in which genetic control strategies may be deployed. There is evidence from laboratory studies that age, body size, and conditions during larval development contribute to male mating success; however, verification of these findings in natural settings is lacking. Although fitness assessments of transgenic or sterile males in genetic control programs are often performed in the laboratory using laboratory-adapted colonies, we advocate that fitness studies are conducted in semi-field cages under ambient conditions where insects are challenged with wild-type mosquitoes to determine their true potential. Because of the considerable amount of time and costs involved with the execution of cage trials we recommend that researchers plan field cage studies as early as possible in the assessment process to prevent time delays.