Abstract
Some proposed genetics-based vector control methods aim to suppress or eliminate a mosquito population in a similar manner to the sterile insect technique. One approach under development in Anopheles mosquitoes uses homing endonuclease genes (HEGs)—selfish genetic elements (inherited at greater than Mendelian rate) that can spread rapidly through a population even if they reduce fitness. HEGs have potential to drive introduced traits through a population without large-scale sustained releases. The population genetics of HEG-based systems has been established using discrete-time mathematical models. However, several ecologically important aspects remain unexplored. We formulate a new continuous-time (overlapping generations) combined population dynamic and genetic model and apply it to a HEG that targets and knocks out a gene that is important for survival. We explore the effects of density dependence ranging from undercompensating to overcompensating larval competition, occurring before or after HEG fitness effects, and consider differences in competitive effect between genotypes (wild-type, heterozygotes and HEG homozygotes). We show that population outcomes—elimination, suppression or loss of the HEG—depend crucially on the interaction between these ecological aspects and genetics, and explain how the HEG fitness properties, the homing rate (drive) and the insect's life-history parameters influence those outcomes.
Highlights
Molecular biology tools are facilitating new genetics-based, species-specific methods of controlling insect pest populations, with the intention of improving efficacy over current methods and reducing adverse environmental consequences
Released genetically modified (GM) mosquitoes mate with wild mosquitoes, potentially affecting the population genetics and population dynamics of the natural population, so ecological understanding is important if these vector control approaches are to improve human health [6,7]
Our population genetic outcomes are consistent with previous work [13], albeit with one new element resulting from taking account of the biological time lag
Summary
Molecular biology tools are facilitating new genetics-based, species-specific methods of controlling insect pest populations, with the intention of improving efficacy over current methods and reducing adverse environmental consequences. Transgenic approaches, involving the release of genetically modified (GM) mosquitoes into natural populations, include a broad class of population reduction methods aiming to suppress the numbers to a lower level or possibly local elimination, based on the principles of the sterile insect technique (SIT) [5]. The HEG sits inside its recognition sequence, so, in a heterozygous individual, the target sequence on the homologous chromosome is cut, and the cell’s DNA repair
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