Rodent malaria-resistant strains of the mosquito, Anopheles gambiae, have slower population growth than -susceptible strains.
BACKGROUND
Trade-offs between anti-parasite defence mechanisms and other life history traits limit the evolution of host resistance to parasites and have important implications for understanding diseases such as malaria. Mosquitoes have not evolved complete resistance to malaria parasites and one hypothesis is that anti-malaria defence mechanisms are costly.


RESULTS
We used matrix population models to compare the population growth rates among lines of Anopheles gambiae that had been selected for resistance or high susceptibility to the rodent malaria parasite, Plasmodium yoelii nigeriensis. The population growth rate of the resistant line was significantly lower than that of the highly susceptible and the unselected control lines, regardless of whether mosquitoes were infected with Plasmodium or not. The lower population growth of malaria-resistant mosquitoes was caused by reduced post blood-feeding survival of females and poor egg hatching.


CONCLUSIONS
With respect to eradicating malaria, the strategy of releasing Plasmodium-resistant Anopheles mosquitoes is unlikely to be successful if the costs of Plasmodium-resistance in the field are as great as the ones measured in this study. High densities of malaria-resistant mosquitoes would have to be maintained by continuous release from captive breeding facilities.
Voordouw
Maarten J
MJ
Department of Biology, University of Victoria, PO Box 3020, Station CSC, Victoria, British Columbia, V8W 3N5, Canada. mjvoordouw@gmail.com
Anholt
Bradley R
BR
Taylor
Pam J
PJ
Hurd
Hilary
H
D000818:Animals; D000852:Anopheles / Q000235:genetics / Q000469:parasitology* / Q000502:physiology; D004198:Disease Susceptibility; D004777:Environment; D005838:Genotype; D007303:Insect Vectors / Q000235:genetics / Q000469:parasitology* / Q000502:physiology; D008018:Life Cycle Stages; D008288:Malaria / Q000635:transmission; D008954:Models, Biological; D010967:Plasmodium yoelii / Q000472:pathogenicity*; D011156:Population Density; D011158:Population Growth