title: Vector competence of Aedes aegypti mosquitoes for filarial nematodes is affected by age and nutrient limitation.
abstract: Mosquitoes are one of the most important vectors of human disease. The ability of mosquitoes to transmit disease is dependent on the age structure of the population, as mosquitoes must survive long enough for the parasites to complete their development and infect another human. Age could have additional effects due to mortality rates and vector competence changing as mosquitoes senesce, but these are comparatively poorly understood. We have investigated these factors using the mosquito Aedes aegypti and the filarial nematode Brugia malayi. Rather than observing any effects of immune senescence, we found that older mosquitoes were more resistant, but this only occurred if they had previously been maintained on a nutrient-poor diet of fructose. Constant blood feeding reversed this decline in vector competence, meaning that the number of parasites remained relatively unchanged as mosquitoes aged. Old females that had been maintained on fructose also experienced a sharp spike in mortality after an infected blood meal ("refeeding syndrome") and few survived long enough for the parasite to develop. Again, this effect was prevented by frequent blood meals. Our results indicate that old mosquitoes may be inefficient vectors due to low vector competence and high mortality, but that frequent blood meals can prevent these effects of age.
authors.affiliation: Department of Genetics, University of Cambridge, Downing Street, Cambridge CB24 6BG, United Kingdom. Electronic address: cristina.ariani@gmail.com.
authors.forename: Cristina V
authors.initials: CV
authors.lastname: Ariani
authors.affiliation: Department of Genetics, University of Cambridge, Downing Street, Cambridge CB24 6BG, United Kingdom. Electronic address: p.juneja@gen.cam.ac.uk.
authors.forename: Punita
authors.initials: P
authors.lastname: Juneja
authors.affiliation: Department of Genetics, University of Cambridge, Downing Street, Cambridge CB24 6BG, United Kingdom. Electronic address: smith.sophia@hotmail.co.uk.
authors.forename: Sophia
authors.initials: S
authors.lastname: Smith
authors.affiliation: Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, United Kingdom. Electronic address: matthew.tinsley@stir.ac.uk.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Tinsley
authors.affiliation: Department of Genetics, University of Cambridge, Downing Street, Cambridge CB24 6BG, United Kingdom. Electronic address: f.jiggins@gen.cam.ac.uk.
authors.forename: Francis M
authors.initials: FM
authors.lastname: Jiggins
mesh_terms: D000330:Aedes / Q000469:parasitology*; D000367:Age Factors; D000818:Animals; D005260:Female; D005370:Filarioidea / Q000254:growth & development*; D005632:Fructose / Q000008:administration & dosage; D007303:Insect Vectors / Q000469:parasitology*
chemical_list: D005632:Fructose
keywords: Ageing; Brugia malayi; Mosquito; Nutrition; Refeeding syndrome; Survival