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opencc-zeroDec 2013View details →

Data from: Reduced survival and reproductive success generates selection pressure for the dengue mosquito Aedes aegypti to evolve resistance against infection by the microsporidian parasite Vavraia culicis

The success and sustainability of control measures aimed at reducing the transmission of mosquito-borne diseases will depend on how they influence the fitness of mosquitoes in targeted populations. We investigated the effects of the microsporidian parasite Vavraia culicis on the survival, blood-feeding behaviour and reproductive success of female Aedes aegypti mosquitoes, the main vector of dengue. Infection reduced survival to adulthood and increased adult female mosquito age-dependent mortality relative to uninfected individuals; this additional mortality was closely correlated with the number of parasite spores they harboured when they died. In the first gonotrophic cycle, infected females were less likely to blood-feed, took smaller meals when they did so, and developed fewer eggs than uninfected females. Even though the conditions of this laboratory study favoured minimal developmental times, the costs of infection were already being experienced by the time females reached an age at which they could first reproduce. These results suggest there will be selection pressure for mosquitoes to evolve resistance against this pathogen if it is used as an agent in a control program to reduce the transmission of mosquito-borne human diseases.

Data from: Existing infection facilitates establishment and density of malaria parasites in their mosquito vector

Very little is known about how vector-borne pathogens interact within their vector and how this impacts transmission. Here we show that mosquitoes can accumulate mixed strain malaria infections after feeding on multiple hosts. We found that parasites have a greater chance of establishing and reach higher densities if another strain is already present in a mosquito. Mixed infections contained more parasites but these larger populations did not have a detectable impact on vector survival. Together these results suggest that mosquitoes taking multiple infective bites may disproportionally contribute to malaria transmission. This will increase rates of mixed infections in vertebrate hosts, with implications for the evolution of parasite virulence and the spread of drug-resistant strains. Moreover, control measures that reduce parasite prevalence in vertebrate hosts will reduce the likelihood of mosquitoes taking multiple infective feeds, and thus disproportionally reduce transmission. More generally, our study shows that the types of strain interactions detected in vertebrate hosts cannot necessarily be extrapolated to vectors.

opencc-zeroMar 2020View details →

Optimal control approaches for combining medicines and mosquito control in tackling dengue

Dengue is a debilitating and devastating viral infection spread by mosquito vectors, and over half the world's population currently live at risk of dengue (and other flavivirus) infections. Here we use an integrated epidemiological and vector ecology framework to predict optimal approaches for tackling dengue. Our aim is to investigate how vector control and/or vaccination strategies can be best combined and implemented for dengue disease control on small networks, and whether these optimal strategies differ under different circumstances. We show that that a combination of vaccination programmes and the release of genetically modified self-limiting mosquitoes (comparable to sterile insect approaches) is always considered the most beneficial strategy for reducing the number of infected individuals, due to both methods having differing impacts on the underlying disease dynamics. Additionally, depending on the impact of human movement on the disease dynamics, the optimal way to combat the spread of dengue is to focus prevention efforts on large population centres. Using mathematical frameworks, such as optimal control, are essential in developing predictive management and mitigation strategies for dengue disease control.

Data from: High chlorpyrifos resistance in Culex pipiens mosquitoes: strong synergy between resistance genes

We investigated the genetic determinism of high chlorpyrifos resistance (HCR), a phenotype first described in 1999 in Culex pipiens mosquitoes surviving chlorpyrifos doses greater than or equal to1 mg l−1 and more recently found in field samples from Tunisia, Israel or Indian Ocean islands. Through chlorpyrifos selection, we selected several HCR strains that displayed over 10 000-fold resistance. All strains were homozygous for resistant alleles at two main loci: the ace-1 gene, with the resistant ace-1R allele expressing the insensitive G119S acetylcholinesterase, and a resistant allele of an unknown gene (named T) linked to the sex and ace-2 genes. We constructed a strain carrying only the T-resistant allele and studied its resistance characteristics. By crossing this strain with strains harboring different alleles at the ace-1 locus, we showed that the resistant ace-1R and the T alleles act in strong synergy, as they elicited a resistance 100 times higher than expected from a simple multiplicative effect. This effect was specific to chlorpyrifos and parathion and was not affected by synergists. We also examined how HCR was expressed in strains carrying other ace-1-resistant alleles, such as ace-1V or the duplicated ace-1D allele, currently spreading worldwide. We identified two major parameters that influenced the level of resistance: the number and the nature of the ace-1-resistant alleles and the number of T alleles. Our data fit a model that predicts that the T allele acts by decreasing chlorpyrifos concentration in the compartment targeted in insects.

opencc-zeroDec 2015View details →

Data from: Predator diversity reduces habitat colonization by mosquitoes and midges

Changes in predator diversity via extinction and invasion are increasingly widespread and can have important ecological and socio-economic consequences. Anticipating and managing these consequences requires understanding how predators shape ecological communities. Previous predator biodiversity research has focused on post-colonization processes. However, predators can also shape communities by altering patterns of prey habitat selection during colonization. The sensitivity of this non-consumptive top down mechanism to changes in predator diversity is largely unexamined. To address this gap, we examined patterns of dipteran oviposition habitat selection in experimental aquatic habitats in response to varied predator species richness while holding predator abundance constant. Caged predators were used in order to disentangle behavioural oviposition responses to predator cues from potential post-oviposition consumption of eggs and larvae. We hypothesized that because increases in predator richness often result in greater prey mortality than would be predicted from independent effects of predators, prey should avoid predator-rich habitats during colonization. Consistent with this hypothesis, predator-rich habitats received 48% fewer dipteran eggs than predicted, including 60% fewer mosquito eggs and 38% fewer midge eggs. Our findings highlight the potentially important links between predator biodiversity, prey habitat selection and the ecosystem service of pest regulation.

opencc-zeroDec 2017View details →

Data from: Discovery and exploitation of a natural ecological trap for a mosquito disease vector

Ecological traps occur due to a mismatch between a habitat's attractiveness and quality, wherein organisms show preference for low-quality habitats over other available high-quality habitats. Our previous research identified leaf litter from common blackberry (Rubus allegheniensis) as a natural ecological trap for an important vector for West Nile virus (Culex pipiens), attracting mosquitoes to oviposit in habitats deleterious to the survival of their larvae. Here we demonstrate that manipulation of leaf litter in stormwater catch basins, an important source of disease vector mosquitoes in urban environments, can increase Cx. pipiens oviposition but reduce survival. In a series of experiments designed to elucidate the mechanisms that explain the attractive and lethal properties of this native plant, behavioral bioassays suggest that oviposition site selection by Cx. pipiens is mediated primarily by chemical cues as leaves decompose. However, we also show that juvenile mosquito survival mainly is related to the suitability of the bacterial community in the aquatic habitat for mosquito nutritional needs, which does not appear to create a cue that influences oviposition choice. This mismatch between oviposition cues and drivers of larval habitat quality may account for the ecological trap phenomenon detected in this study. Our findings provide new insights into potential mechanistic pathways by which ecological traps may occur in nature and proof-of-concept for a new 'attract-and-kill' tool for mosquito control.

opencc-zeroOct 2019View details →

Supplementary data for: Mosquito phytophagy – sources exploited, ecological function, and evolutionary transition to haematophagy

This dataset consists of two files: Floral visitation records of mosquitoes Plant sugar, primarily in the form of floral nectar, is the ubiquitous basic food of adult mosquitoes. However, records of mosquito floral visitation are not usually the focus of research publications and, as such, are often reported as secondary parts of larger studies and are scattered throughout more than a century of scientific literature. Here we provide a summary of more than 500 recorded literature and field instances of floral and extra-floral nectary visitation by mosquitoes, including the plant and mosquito species involved as well as known pollination records. file name: Summary_of_Field_Mosquito_Floral_Visitation_Instances.xlsx Summary of floral semiochemical blends that are attractive to mosquitoes Floral nectar is the primary food source of adult mosquitoes and mosquitoes, along with many other pollinators, use floral semiochemicals to locate this resource. Here we provide a summary of floral semiochemical blends attractive to mosquitoes that have been reported in the literature. The mosquito species involved have also been listed. file name: Summary_of_Floral_Semiochemical_Blends_Attractive_to_Mosquitoes.xlsx

Data from: Transgenerational effect of infection in Plasmodium-infected mosquitoes

Transgenerational effects of infection have a huge potential to influence the prevalence and intensity of infections in vectors and, by extension, disease epidemiology. These transgenerational effects may increase the fitness of offspring through the transfer of protective immune factors. Alternatively, however, infected mothers may transfer the costs of infection to their offspring. Although transgenerational immune protection has been described in a dozen invertebrate species, we still lack a complete picture of the incidence and importance of transgenerational effects of infection in most invertebrate groups. The existence of transgenerational infection effects in mosquito vectors is of particular interest because of their potential for influencing parasite prevalence and intensity and, by extension, disease transmission. Here we present what we believe to be the first study on transgenerational infection effects in a mosquito vector infected with malaria parasites. The aim of this experiment was to quantify both the benefits and the costs of having an infected mother. We find no evidence of transgenerational protection in response to a Plasmodium infection. Having an infected mother does, however, entail considerable fecundity costs for the offspring: fecundity loss is three times higher in infected offspring issued from infected mothers than in infected offspring issued from uninfected mothers. We discuss the implications of our results and we call for more studies looking at transgenerational effects of infection in disease vectors.

opencc-zeroDec 2012View details →

Data from: Large fluctuations in the effective population size of the malaria mosquito Anopheles gambiae s.s. during vector control cycle

On Bioko Island, Equatorial Guinea, indoor residual spraying (IRS) has been part of the Bioko Island Malaria Control Project since early 2004. Despite success in reducing childhood infections, areas of high transmission remained on the island. We therefore examined fluctuations in the effective population size (N_e) of the malaria vector Anopheles gambiae in an area of persistent high transmission over two spray rounds. We analyzed data for 13 microsatellite loci from 791 An. gambiae specimens collected at 6 time points in 2009 and 2010 and reconstructed the demographic history of the population during this period using Approximate Bayesian Computation (ABC). Our analysis shows that IRS rounds have a big impact on N_e, reducing it by 65% to 92% from pre-spray round N_e. More importantly our analysis shows that after 3-5 months, the An. gambiae population rebounded by 2,818% compared to shortly following the spray round. Our study underscores the importance of adequate spray round frequency to provide continuous suppression of mosquito populations, and that increased spray round frequency should substantially improve the efficacy of IRS campaigns. It also demonstrates the ability of ABC to reconstruct a detailed demographic history across only a few tens of generations in a large population.

opencc-zeroDec 2015View details →

Data from: Fitness consequences of altered feeding behavior in immune-challenged mosquitoes

Background: Malaria-infected mosquitoes have been reported to be more likely to take a blood meal when parasites are infectious than when non-infectious. This change in feeding behavior increases the likelihood of malaria transmission, and has been considered an example of parasite manipulation of host behavior. However, immune challenge with heat-killed Escherichia coli induces the same behavior, suggesting that altered feeding behavior may be driven by adaptive responses of hosts to cope with an immune response, rather than by parasite-specific factors. Here we tested the alternative hypothesis that down-regulated feeding behavior prior to infectiousness is a mosquito adaptation that increases fitness during infection. Methods: We measured the impact of immune challenge and blood feeding on the fitness of individual mosquitoes. After an initial blood meal, Anopheles stephensi Liston mosquitoes were experimentally challenged with heat-killed E. coli at a dose known to mimic the same temporal changes in mosquito feeding behavior as active malaria infection. We then tracked daily egg production and survivorship of females maintained on blood-feeding regimes that either mimicked down-regulated feeding behaviors observed during early malaria infection, or were fed on a four-day feeding cycle typically associated with uninfected mosquitoes. Results: Restricting access to blood meals enhanced mosquito survival but lowered lifetime reproduction. Immune- challenge did not impact either fitness component. Combining fecundity and survival to estimate the population- scale intrinsic rate of increase (r), we found that, contrary to the mosquito adaptation hypothesis, mosquito fitness decreased if blood feeding was delayed following an immune challenge. Conclusions: Our data provide no support for the idea that malaria-induced suppression of blood feeding is an adaptation by mosquitoes to reduce the impact of immune challenge. Alternatively, the behavioral alterations may be neither host nor parasite adaptations, but rather a consequence of constraints imposed on feeding by activation of the mosquito immune response, i.e. non-adaptive illness-induced anorexia. Future work incorporating field conditions and different immune challenges could further clarify the effect of altered feeding on mosquito and parasite fitness.

Data from: Epigenetic alterations and decreasing insecticide sensitivity of the Asian tiger mosquito Aedes albopictus

A range of environmental factors, including chemicals, can affect epigenetic processes in organisms leading to variations in phenotype. Thus, epigenetics displays an important environmentally responsive element. The transgenerational impact of environmental stressors on DNA methylation and phenotype was the focus of this study. The influence of two known DNA methylation-changing agents, the phytoestrogen genistein and the fungicide vinclozolin, on the overall DNA methylation level in the Asian tiger mosquito Aedes albopictus was investigated. The experiment comprised four generations in a full life-cycle design with an exposed parental generation and three consecutive non-exposed offspring generations. Application of the methylation agents to the parental generation of the study led to an alteration of the global DNA methylation level of the exposed individuals and those in two subsequent generations. The phenotypic variability of the offspring generations was assessed by examining their insecticide sensitivity. Here, a significant decrease in sensitivity (p<0.01) towards the model insecticide imidacloprid revealed alterations of the mosquito's phenotype in two subsequent generations. Thus, the evaluation of A. albopictus from an epigenetic perspective can contribute important information to the study of the high adaptability of this invasive disease vector to new environments, and its underlying mechanisms.

FIGURE 148 in Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission

FIGURE 148. Aedes (Stegomyia) albopictus.

FIGURE 147 in Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission

FIGURE 147. Aedes (Stegomyia) albopictus.

FIGURE 145 in Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission

FIGURE 145. Aedes (Stegomyia) aegypti.

FIGURE 143 in Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission

FIGURE 143. Aedes (Stegomyia) albopictus.

FIGURE 141 in Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission

FIGURE 141. Aedes (Stegomyia) albopictus.

FIGURE 140 in Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission

FIGURE 140. Ochlerotatus (Gymnometopa) mediovittatus (PS, pecten spine).

FIGURE 133 in Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission

FIGURE 133. Aedes (Stegomyia) albopictus.

FIGURE 139 in Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission

FIGURE 139. Ochlerotatus (Gymnometopa) mediovittatus.

FIGURE 132 in Pictorial keys for the identification of mosquitoes (Diptera: Culicidae) associated with Dengue Virus Transmission

FIGURE 132. Aedes (Stegomyia) aegypti.