Abstract

A method to reliably predict the age structure of malaria mosquitoes would be valuable in predicting the efficacy of vector control tools and provide important insights to inform models of malaria transmission.  We have previously shown that Rapid Evaporative Ionisation Mass Spectrometry could determine the age and species of laboratory reared mosquitoes and culicine mosquitoes from a river estuary in the United Kingdom.  Here we investigated the robustness of this methodology by introducing additional environmental, genetic and physiological diversity in experiments using laboratory reared and field collected Anopheles gambiae mosquitoes.  REIMS could reliably separate mosquitoes into 3 or 5 age groups with > 80 % accuracy using mosquitoes of mixed physiological status reared in insectaries or from larval collections reared to adults in semi-field stations in Burkina Faso.  In addition, REIMS could distinguish mosquitoes that were nulliparous from those that had undergone one or two oviposition cycles with an accuracy of 87 %.  In a proof of principle experiment we demonstrate that REIMS can readily distinguish between mosquitoes infected with Plasmodium berghei from non-infected. Furthermore, we show that age grading is possible using only mosquito abdomens, leaving biomass for further molecular biological experiments. Finally, we used the model generated from mixed field collections to estimate the age structure of mosquitoes collected from inside houses and were able to show a shifting age structure matching the time retained in the insectary post collections.