title: Larval and adult environmental temperatures influence the adult reproductive traits of Anopheles gambiae s.s.
abstract: BACKGROUND
  Anopheles mosquito life-history parameters and population dynamics strongly influence malaria transmission, and environmental factors, particularly temperature, strongly affect these parameters. There are currently some studies on how temperature affects Anopheles gambiae s.s. survival but very few exist examining other life-history traits. We investigate here the effect of temperature on population dynamics parameters.
  
  
  METHODS
  Anopheles gambiae s.s. immatures were reared individually at 23 ± 1 °C, 27 ± 1 °C, 31 ± 1 °C, and 35 ± 1 °C, and adults were held at their larval temperature or at one of the other temperatures. Larvae were checked every 24 h for development to the next stage and measured for size; wing length was measured as a proxy for adult size. Females were blood fed three times, and the number of females feeding and laying eggs was counted. The numbers of eggs and percentage of eggs hatched were recorded.
  
  
  RESULTS
  Increasing temperatures during the larval stages resulted in significantly smaller larvae (p = 0.005) and smaller adults (p < 0.001). Adult temperature had no effect on the time to egg laying, and the larval temperature of adults only affected the incubation period of the first egg batch. Temperature influenced the time to hatching of eggs, as well as the time to development at every stage. The number of eggs laid was highest when adults were kept at 27 °C, and lowest at 31 °C, and higher adult temperatures decreased the proportion of eggs hatching after the second and third blood meal. Higher adult temperatures significantly decreased the probability of blood feeding, but the larval temperature of adults had no influence on the probability of taking a blood meal. Differences were observed between the first, second, and third blood meal in the times to egg laying and hatching, number of eggs laid, and probabilities of feeding and laying eggs.
  
  
  CONCLUSIONS
  Our study shows that environmental temperature during the larval stages as well as during the adult stages affects Anopheles life-history parameters. Data on how temperature and other climatic factors affect vector life-history parameters are necessary to parameterise more reliably models predicting how global warming may influence malaria transmission.
authors.affiliation: Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK. celine.jucht@imperial.ac.uk.
authors.forename: Céline D
authors.initials: CD
authors.lastname: Christiansen-Jucht
authors.affiliation: Department of Public Health and Policy, Faculty of Health and Life Sciences, University of Liverpool, 33 Finsbury Square, London, EC2A 1AG, UK. paul.parham@liverpool.ac.uk.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Parham
authors.affiliation: Department of Epidemiology and Public Health, Health Interventions Unit, Swiss TPH, Basel, Switzerland. asaddler@ihi.or.tz.
authors.forename: Adam
authors.initials: A
authors.lastname: Saddler
authors.affiliation: Faculté des Sciences, Institut de Biologie, Université de Neuchâtel, Rue Emile-Argand 11, CH-2000, Neuchâtel, Switzerland. jacob.koella@unine.ch.
authors.forename: Jacob C
authors.initials: JC
authors.lastname: Koella
authors.affiliation: Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK. m.basanez@imperial.ac.uk.
authors.forename: María-Gloria
authors.initials: MG
authors.lastname: Basáñez
mesh_terms: D000818:Animals; D000852:Anopheles / Q000254:growth & development* / Q000502:physiology; D004781:Environmental Exposure; D007814:Larva / Q000254:growth & development; D012726:Sexual Behavior, Animal; D013696:Temperature