Anopheles mortality is both age- and Plasmodium-density dependent: implications for malaria transmission

Dawes, Emma J; Churcher, Thomas S.; Zhuang, Shijie; Sinden, Robert E.; Basáñez, María-Gloria

doi:10.1186/1475-2875-8-228

Cited by 100 publications

(128 citation statements)

References 85 publications

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“…Evidence is now accumulating that input parasite densities affect the progression of the infection as well as mosquito signaling pathways and mortality; however, the actual impact of infection intensities on mosquito responses is still unclear, and very few studies have considered infection intensities in the analysis of infection data (7,24,26). Here we have carried out A. gambiae infections with geographically related P. falciparum parasites sampled from naturally infected children in order to investigate the impact of different infection intensities on the mosquito midgut transcriptome.…”

Section: Rna Interference (Rnai)-mediated Gene Silencing Provides Inimentioning

confidence: 99%

“…In fact, A. gambiae is not a natural vector of P. berghei, and the intensities of P. berghei infection are much higher than those commonly observed in nature with P. falciparum (2). Differences in P. falciparum infection levels have been associated with several genomic loci and have been shown to depend on vector-parasite genotype-by-genotype interactions (12,16,29).Evidence is now accumulating that input parasite densities affect the progression of the infection as well as mosquito signaling pathways and mortality; however, the actual impact of infection intensities on mosquito responses is still unclear, and very few studies have considered infection intensities in the analysis of infection data (7,24,26). Here we have carried out A. gambiae infections with geographically related P. falciparum parasites sampled from naturally infected children in order to investigate the impact of different infection intensities on the mosquito midgut transcriptome.…”

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confidence: 99%

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Infection Intensity-Dependent Responses of Anopheles gambiae to the African Malaria Parasite Plasmodium falciparum

et al. 2011

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Malaria remains a devastating disease despite efforts at control and prevention. Extensive studies using mostly rodent infection models reveal that successful Plasmodium parasite transmission by the African mosquito vector Anopheles gambiae depends on finely tuned vector-parasite interactions. Here we investigate the transcriptional response of A. gambiae to geographically related Plasmodium falciparum populations at various infection intensities and different infection stages. These responses are compared with those of mosquitoes infected with the rodent parasite Plasmodium berghei. We demonstrate that mosquito responses are largely dependent on the intensity of infection. A major transcriptional suppression of genes involved in the regulation of midgut homeostasis is detected in low-intensity P. falciparum infections, the most common type of infection in Africa. Importantly, genes transcriptionally induced during these infections tend to be phylogenetically unique to A. gambiae. These data suggest that coadaptation between vectors and parasites may act to minimize the impact of infection on mosquito fitness by selectively suppressing specific functional classes of genes. RNA interference (RNAi)-mediated gene silencing provides initial evidence for important roles of the mosquito G protein-coupled receptors (GPCRs) in controlling infection intensity-dependent antiparasitic responses.Malaria is a devastating parasitic disease that remains an enormous public health burden, especially in sub-Saharan Africa, where the deadliest of the malaria parasites, Plasmodium falciparum, is transmitted mainly by Anopheles gambiae mosquitoes. Extensive laboratory studies of mosquito-parasite interactions have exploited genomics and postgenomics technologies for gene expression profiling and functional characterization to generate new knowledge. It has been established that parasite development in the mosquito midgut is the most vulnerable stage of the entire transmission cycle. This appears to be due largely to robust mosquito responses that effectively reduce the number of parasites able to invade the midgut and establish infections in the hemolymph (8,22,30). Therefore, detailed understanding of the vector-parasite interactions could lead to novel strategies that can supplement current control methods.Recent studies have identified mosquito genes that affect P. falciparum and the rodent malaria parasite, Plasmodium berghei, which is often used as a laboratory model, similarly; however, such conserved responses can only partly explain the vector-parasite interactions in natural settings (6,8,11,20,21). In fact, A. gambiae is not a natural vector of P. berghei, and the intensities of P. berghei infection are much higher than those commonly observed in nature with P. falciparum (2). Differences in P. falciparum infection levels have been associated with several genomic loci and have been shown to depend on vector-parasite genotype-by-genotype interactions (12,16,29).Evidence is now accumulating that input parasite densities affe...

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Section: Rna Interference (Rnai)-mediated Gene Silencing Provides Inimentioning

confidence: 99%

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confidence: 99%

Infection Intensity-Dependent Responses of Anopheles gambiae to the African Malaria Parasite Plasmodium falciparum

et al. 2011

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“…[8][9][10] These concerns would be minor if vectorial capacity in two environments were to be overestimated or underestimated to the same degree (i.e., a quantitative difference), 5 but they could be particularly serious if use of an exponential mortality function results in qualitatively different outcomes when environments or success of control measures are compared. One theoretical investigation so far suggests that this may be the case.…”

Section: Introductionmentioning

confidence: 99%

Effects of Plant-Community Composition on the Vectorial Capacity and Fitness of the Malaria Mosquito Anopheles gambiae

Stone¹,

Jackson²,

Foster³

2012

The American Journal of Tropical Medicine and Hygiene

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Abstract. Dynamics of Anopheles gambiae abundance and malaria transmission potential rely strongly on environmental conditions. Female and male An. gambiae use sugar and are affected by its absence, but how the presence or absence of nectariferous plants affects An. gambiae abundance and vectorial capacity has not been studied. We report on four replicates of a cohort study performed in mesocosms with sugar-poor and sugar-rich plants, in which we measured mosquito survival, biting rates, and fecundity. Survivorship was greater with access to sugar-rich plant species, and mortality patterns were age-dependent. Sugar-poor populations experienced Weibull mortality patterns, and of four populations in the sugar-rich environment, two female and three male subpopulations were better fitted by Gompertz functions. A tendency toward higher biting rates in sugar-poor mesocosms, particularly for young females, was found. Therefore, vectorial capacity was pulled in opposing directions by nectar availability, resulting in highly variable vectorial capacity values.

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“…Dawes et al also reported age-dependent mortality in laboratory adult populations of An. stephensi [2]. Mosquito senescence has been documented in Aedes aegypti, both under laboratory and semi-field conditions [36,37].…”

Section: Discussionmentioning

confidence: 99%

Temperature during larval development and adult maintenance influences the survival of Anopheles gambiae s.s.

Christiansen-Jucht

Parham

Saddler

et al. 2014

Parasites & Vectors

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Background: Malaria transmission depends on vector life-history parameters and population dynamics, and particularly on the survival of adult Anopheles mosquitoes. These dynamics are sensitive to climatic and environmental factors, and temperature is a particularly important driver. Data currently exist on the influence of constant and fluctuating adult environmental temperature on adult Anopheles gambiae s.s. survival and on the effect of larval environmental temperature on larval survival, but none on how larval temperature affects adult life-history parameters. Methods: Mosquito larvae and pupae were reared individually at different temperatures (23 ± 1°C, 27 ± 1°C, 31 ± 1°C, and 35 ± 1°C), 75 ± 5% relative humidity. Upon emergence into imagoes, individual adult females were either left at their larval temperature or placed at a different temperature within the range above. Survival was monitored every 24 hours and data were analysed using non-parametric and parametric methods. The Gompertz distribution fitted the survivorship data better than the gamma, Weibull, and exponential distributions overall and was adopted to describe mosquito mortality rates. Results: Increasing environmental temperature during the larval stages decreased larval survival (p < 0.001). Increases of 4°C (from 23°C to 27°C, 27°C to 31°C, and 31°C to 35°C), 8°C (27°C to 35°C) and 12°C (23°C to 35°C) statistically significantly increased larval mortality (p < 0.001). Higher environmental temperature during the adult stages significantly lowered adult survival overall (p < 0.001), with increases of 4°C and 8°C significantly influencing survival (p < 0.001). Increasing the larval environment temperature also significantly increased adult mortality overall (p < 0.001): a 4°C increase (23°C to 27°C) did not significantly affect adult survival (p > 0.05), but an 8°C increase did (p < 0.05). The effect of a 4°C increase in larval temperature from 27°C to 31°C depended on the adult environmental temperature. The data also suggest that differences between the temperatures of the larval and adult environments affects adult mosquito survival. Conclusions: Environmental temperature affects Anopheles survival directly during the juvenile and adult stages, and indirectly, since temperature during larval development significantly influences adult survival. These results will help to parameterise more reliable mathematical models investigating the potential impact of temperature and global warming on malaria transmission.

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Anopheles mortality is both age- and Plasmodium-density dependent: implications for malaria transmission

Cited by 100 publications

References 85 publications

Infection Intensity-Dependent Responses of Anopheles gambiae to the African Malaria Parasite Plasmodium falciparum

Infection Intensity-Dependent Responses of Anopheles gambiae to the African Malaria Parasite Plasmodium falciparum

Effects of Plant-Community Composition on the Vectorial Capacity and Fitness of the Malaria Mosquito Anopheles gambiae

Temperature during larval development and adult maintenance influences the survival of Anopheles gambiae s.s.

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