Characterizing the Aedes aegypti Population in a Vietnamese Village in Preparation for a Wolbachia-Based Mosquito Control Strategy to Eliminate Dengue

Background

A life-shortening strain of the obligate intracellular bacteria Wolbachia, called wMelPop, is seen as a promising new tool for the control of Aedes aegypti. However, developing a vector control strategy based on the release of mosquitoes transinfected with wMelPop requires detailed knowledge of the demographics of the target population.

Methodology/Principal Findings

In Tri Nguyen village (611 households) on Hon Mieu Island in central Vietnam, we conducted nine quantitative entomologic surveys over 14 months to determine if Ae. aegypti populations were spatially and temporally homogenous, and to estimate population size. There was no obvious relationship between mosquito (larval, pupal or adult) abundance and temperature and rainfall, and no area of the village supported consistently high numbers of mosquitoes. In almost all surveys, key premises produced high numbers of Ae. aegypti. However, these premises were not consistent between surveys. For an intervention based on a single release of wMelPop-infected Ae. aegypti, release ratios of infected to uninfected adult mosquitoes of all age classes are estimated to be 1.8–6.7∶1 for gravid females (and similarly aged males) or teneral adults, respectively. We calculated that adult female mosquito abundance in Tri Nguyen village could range from 1.1 to 43.3 individuals of all age classes per house. Thus, an intervention could require the release of 2–78 wMelPop-infected gravid females and similarly aged males per house, or 7–290 infected teneral female and male mosquitoes per house.

Conclusions/Significance

Given the variability we encountered, this study highlights the importance of multiple entomologic surveys when evaluating the spatial structure of a vector population or estimating population size. If a single release of wMelPop-infected Ae. aegypti were to occur when wild Ae. aegypti abundance was at its maximum, a preintervention control program would be necessary to ensure that there was no net increase in mosquito numbers. However, because of the short-term temporal heterogeneity, the inconsistent spatial structure and the impact of transient key premises that we observed, the feasibility of multiple releases of smaller numbers of mosquitoes also needs to be considered. In either case, fewer wMelPop-infected mosquitoes would then need to be released, which will likely be more acceptable to householders.     

Experience‐ and age‐mediated oviposition behaviour in the yellow fever mosquito Stegomyia aegypti (=Aedes aegypti)

In repeated behaviours such as those of feeding and reproduction, past experiences can inform future behaviour. By altering their behaviour in response to environmental stimuli, insects in highly variable landscapes can tailor their behaviour to their particular environment. In particular, female mosquitoes may benefit from plasticity in their choice of egg‐laying site as these sites are often temporally variable and clustered. The opportunity to adapt egg‐laying behaviour to past experience also exists for mosquito populations as females typically lay eggs multiple times throughout their lives. Whether experience and age affect egg‐laying (or oviposition) behaviour in the mosquito Stegomyia aegypti (=Aedes aegypti) (Diptera: Culicidae) was assessed using a wind tunnel. Initially, gravid mosquitoes were provided with a cup containing either repellent or well water. After ovipositing in these cups, the mosquitoes were blood‐fed and introduced into a wind tunnel. In this wind tunnel, an oviposition cup containing repellent was placed in the immediate vicinity of the gravid mosquitoes. A cup containing well water was placed at the opposite end of the tunnel so that if the females flew across the chamber, they encountered the well water cup, in which they readily laid eggs. Mosquitoes previously exposed to repellent cups became significantly more likely to later lay eggs in repellent cups, suggesting that previous experience with suboptimal oviposition sites informs mosquitoes of the characteristics of nearby oviposition sites. These results provide further evidence that mosquitoes modify behaviour in response to environmental information and are demonstrated in a vector species in which behavioural plasticity may be ecologically and epidemiologically meaningful.     

Sex‐skewed trophic impacts in ephemeral wetlands

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Strategies for introducing Wolbachia to reduce transmission of mosquito-borne diseases

Certain strains of the endosymbiont Wolbachia have the potential to lower the vectorial capacity of mosquito populations and assist in controlling a number of mosquito-borne diseases. An important consideration when introducing Wolbachia-carrying mosquitoes into natural populations is the minimisation of any transient increase in disease risk or biting nuisance. This may be achieved by predominantly releasing male mosquitoes. To explore this, we use a sex-structured model of Wolbachia-mosquito interactions. We first show that Wolbachia spread can be initiated with very few infected females provided the infection frequency in males exceeds a threshold. We then consider realistic introduction scenarios involving the release of batches of infected mosquitoes, incorporating seasonal fluctuations in population size. For a range of assumptions about mosquito population dynamics we find that male-biased releases allow the infection to spread after the introduction of low numbers of females, many fewer than with equal sex-ratio releases. We extend the model to estimate the transmission rate of a mosquito-borne pathogen over the course of Wolbachia establishment. For a range of release strategies we demonstrate that male-biased release of Wolbachia-infected mosquitoes can cause substantial transmission reductions without transiently increasing disease risk. The results show the importance of including mosquito population dynamics in studying Wolbachia spread and that male-biased releases can be an effective and safe way of rapidly establishing the symbiont in mosquito populations.     

Experimental logging alters the abundance and community composition of ovipositing mosquitoes in the southern Appalachians

1. The loss of intact forest via logging can influence vector‐borne disease dynamics in part by altering the abundance or diversity of mosquito species. Using an experimental field approach, we characterised how two types of logging (clearcut and repeat‐entry shelterwood) affected temperate forest mosquito abundance and diversity in southwestern Virginia. 2.From May to September in 2008–2010, infusion‐baited gravid traps were used to collect ovipositing female mosquitoes across experimental forest plots that varied in logging treatment. Of the 29 680 collected adult female mosquitoes, the three dominant taxa captured were Aedes triseriatus (55%), Aedes japonicus (21%), and Culex pipiens/restuans (20%). 3. Logging treatment had a significant effect on the overall number of female mosquitoes caught per trap night, with lower average abundance of females on both logged treatments relative to two types of unlogged, control plots. When the three most abundant mosquito species were examined separately, logging treatment significantly influenced the abundance of both Aedes species, but did not significantly affect C. pipiens/restuans abundance. 4. Logging treatment did not influence the richness or diversity of mosquito species captured in gravid traps. However, logging treatment significantly altered the multivariate community composition of captured mosquitoes, an effect probably mediated by differential species‐specific impacts of logging on abundance. 5. Overall, the results of the present study suggest that the risk of arboviruses transmitted by container‐breeding Aedes species may be lower following a logging event in Appalachian forests because of reduced A. japonicus and A. triseriatus abundance with logging.     

Male Mosquitoes as Vehicles for Insecticide

Background

The auto-dissemination approach has been shown effective at treating cryptic refugia that remain unaffected by existing mosquito control methods. This approach relies on adult mosquito behavior to spread larvicide to breeding sites at levels that are lethal to immature mosquitoes. Prior studies demonstrate that ‘dissemination stations,’ deployed in mosquito-infested areas, can contaminate adult mosquitoes, which subsequently deliver the larvicide to breeding sites. In some situations, however, preventative measures are needed, e.g., to mitigate seasonal population increases. Here we examine a novel approach that combines elements of autocidal and auto-dissemination strategies by releasing artificially reared, male mosquitoes that are contaminated with an insecticide.

Methodology

Laboratory and field experiments examine for model-predicted impacts of pyriproxyfen (PPF) directly applied to adult male Aedes albopictus, including (1) the ability of PPF-treated males to cross-contaminate females and to (2) deliver PPF to breeding sites.

Principal Findings

Similar survivorship was observed in comparisons of PPF-treated and untreated males. Males contaminated both female adults and oviposition containers in field cage tests, at levels that eliminated immature survivorship. Field trials demonstrate an ability of PPF-treated males to transmit lethal doses to introduced oviposition containers, both in the presence and absence of indigenous females. A decline in the Ae. albopictus population was observed following the introduction of PPF-treated males, which was not observed in two untreated field sites.

Conclusions/Significance

The results demonstrate that, in cage and open field trials, adult male Ae. albopictus can tolerate PPF and contaminate, either directly or indirectly, adult females and immature breeding sites. The results support additional development of the proposed approach, in which male mosquitoes act as vehicles for insecticide delivery, including exploration of the approach with additional medically important mosquito species. The novelty and importance of this approach is an ability to safely achieve auto-dissemination at levels of intensity that may not be possible with an auto-dissemination approach that is based on indigenous females. Specifically, artificially-reared males can be released and sustained at any density required, so that the potential for impact is limited only by the practical logistics of mosquito rearing and release, rather than natural population densities and the self-limiting impact of an intervention upon them.     

Monitoring of local populations of the urban mosquito <Emphasis Type="Italic">Culex pipiens pipiens</Emphasis> f. <Emphasis Type="Italic">molestus</Emphasis> Forsk. (Diptera,Culicidae) in St. Petersburg

Monitoring of local populations of the urban mosquito Culex pipiens pipiens f. molestus was carried out in St. Petersburg (Russia) in 1999–2006 for the first time. It included the estimation of the autogeny rate, mean fecundity and wing length of females, sex ratio, and siphonal index of the larvae. The mosquitoes were found in 27 out of the 39 examined basements of dwelling houses in five city districts. The perennial populations can exist only in heated basements flooded with sewage or mixed waters with high level of organic pollution and temperature between 10 and 34°C. Most of the local populations are characterized by high autogeny rate: 80–100% of females lay the first egg batch without blood-feeding, ensuring a long-term existence of autonomous local populations. The mean wing length and mean fecundity varied both between and within local populations, ranging from 3.1 to 5.4 mm and from 32.9 to 105.7 eggs per female, respectively. A significant positive correlation was revealed between autogeny rate and fecundity, on the one hand, and the wing length of females, on the other hand. The latter, in its turn, is affected by the temperature and pollution of basement waters during the larval development. Monitoring of the local populations of the urban mosquito in St. Petersburg has shown them to possess high reproductive potentials, a normal sex ratio, and no infections. The sanitary, hydrotechnical (first of all drainage of basements) and mosquito control measures are necessary in order to reduce mosquito abundance and prevent their further dispersal in the city.     

Diel activity patterns of adult female mosquitoes (Diptera: Culicidae) determined by a novel rotated trap in northeastern Florida,U.S.A.

A novel rotator trap was evaluated to determine the diel activity patterns and physiological state of adult female mosquitoes in St. Augustine, FL, U.S.A. Culex nigripalpus were most active from 19:00‐21:00, followed by 1:00‐3:00, based on collections from the novel rotator trap. Furthermore, analysis of the physiological state of female mosquitoes collected by the novel rotator trap suggested that non‐parous (nulliparous) host‐seeking mosquitoes were more frequently active in the 21:00‐23:00 and 09:00‐19:00 time frames. Parous host‐seeking mosquitoes were more frequently collected from 19:00‐21:00 and 1:00‐3:00. A low abundance of gravid females was collected by the rotator trap, so analysis of their activity periods was inconclusive. These results indicate that the novel rotated trap could be used to detect the diel activity patterns of adult mosquitoes in mosquito control programs and more testing should be conducted in the future.     

Adverse ffects of covert iridovirus infection on life history and demographic parameters of Aedes aegypti

Abstract Sublethal viral infections can cause changes in the body size and demography of insect vectors, with important consequences for population dynamics and the probability that individual mosquitoes will transmit disease. This study examined the effects of covert (sublethal) infection by Invertebrate iridescent virus 6 (IIV‐6) on the demography of female Aedes aegypti and the relationship between key life history parameters in covertly infected female insects compared with healthy (control) insects or non‐infected mosquitoes that had survived exposure to virus inoculum without becoming infected. Of the female mosquitoes that emerged following exposure to virus inoculum and were offered blood meals, 29% (43/150) proved positive for covert IIV‐6 infection. The net reproductive rate (R₀) of covertly infected females was 50% lower for infected females compared to control mosquitoes, whereas non‐infected exposed females had an R₀ approximately 15% lower than that of controls. Reproduction caused a significant decrease of about 13 days in mosquito longevity compared to females that did not reproduce (P < 0.001). Infected females lived 5–8 days less than non‐infected exposed females or controls, respectively (P = 0.028). Infected females and non‐infected exposed females both had significantly shorter wings than control insects (P < 0.001). There was a significant positive correlation between wing length and longevity in covertly infected female mosquitoes but not in control or non‐infected exposed mosquitoes. Longer lived females produced more eggs in all treatments. There were no significant correlations between body size and fecundity or the production of offspring. There was also no correlation between fecundity and fertility, suggesting that sperm inactivation was a more likely cause of decreased fertility in older mosquitoes than sperm depletion. We conclude that covert infection by iridescent virus is likely to reduce the vectorial capacity of this mosquito.     

Effects of global warming on mosquitoes & mosquito‐borne diseases and the new strategies for mosquito control

Global warming has shortened mosquitoes’ lifecycle period and increased the disease transmission rates by mosquito vectors. We reviewed only three mosquito‐borne diseases: malaria, dengue fever, and the Japanese encephalitis. Billions of people get infected with those diseases and millions of people die every year. Although we struggle to find the most effective way to control mosquitoes using various methods (including pesticides), mosquito‐borne diseases are still among the most serious problems being faced. This paper, therefore, reviews the strategies for controlling mosquitoes. The use of pesticides to control mosquitoes might have more negative effects on humans and environments than benefits. Although the development of genetically modified (GM) mosquitoes raises new hopes for effective mosquito control, it will take longer to assess the risks to humans and environments. Furthermore, there has been concern about the possible adverse effects from the release of GM mosquitoes into the environment. The various mosquito traps may not be as effective at controlling only female mosquito populations. Therefore, new strategies for the control of mosquitoes are vital. The smart mosquito counter device was developed by Korean Centre for Disease Control (KCDC) in 2013. The mosquito pest control office is able to set up the appropriate mosquito control strategies by using quantitative mosquito information. The smart device will bring mosquito control in line with modern smart generation technology and the device will also soon be able to identify different mosquito species. This new strategy will change the methods of mosquito control and will provide beneficial effects toward sustainable nature and human health.     

The effect of rainstorms on adult Anopheles funestus behavior and survival

We describe the effect that the passage of a cold front, with a subsequent heavy rainstorm ten days later, had on a population of Anopheles funestus mosquitoes collected exiting houses or in light-traps from a village in southern Mozambique. Temperature effects explained 40% (r=0.634; p <0.001) of the variation in numbers of males collected and 19% of the variation in gravid females collected (r=0.437; p=0.033). The age structure of mosquitoes varied according to distance from the breeding site (χ(2) = 64.1, df 6, p <0.001). The proportion of parous insects that were caught in the light-traps with sacs (χ(2) = 6.33, d.f. 2, p=0.042) and young insects that had mated before being collected (χ(2) = 13,3, d.f. 2, p=0.001) were reduced on the night of the rain but this effect was short lived. It is concluded that the effect of rain on mosquito populations depends on the kind of water body used for larval development.     

Modelling Allee effects in a transgenic mosquito population during range expansion

ABSTRACT

Mosquitoes are vectors for many diseases that cause significant mortality and morbidity. As mosquito populations expand their range, they may undergo mate-finding Allee effects such that their ability to successfully reproduce becomes difficult at low population density. With new technology, creating target specific gene modification may be a viable method for mosquito population control. We develop a mathematical model to investigate the effects of releasing transgenic mosquitoes into newly established, low-density mosquito populations. Our model consists of two life stages (aquatic and adults), which are divided into three genetically distinct groups: heterogeneous and homogeneous transgenic that cause female infertility and a homogeneous wild type. We perform analytical and numerical analyses on the equilibria to determine the level of saturation needed to eliminate mosquitoes in a given area. This model demonstrates the potential for a gene drive system to reduce the spread of invading mosquito populations.     

Age-Dependent Effects of Oral Infection with Dengue Virus on Aedes aegypti (Diptera: Culicidae) Feeding Behavior,Survival, Oviposition Success and Fecundity

Background

Aedes aegypti is the main vector of dengue, a disease that is increasing its geographical range as well as incidence rates. Despite its public health importance, the effect of dengue virus (DENV) on some mosquito traits remains unknown. Here, we investigated the impact of DENV-2 infection on the feeding behavior, survival, oviposition success and fecundity of Ae. aegypti females.

Methods/Principal Findings

After orally-challenging Ae. aegypti females with a DENV-2 strain using a membrane feeder, we monitored the feeding behavior, survival, oviposition success and fecundity throughout the mosquito lifespan. We observed an age-dependent cost of DENV infection on mosquito feeding behavior and fecundity. Infected individuals took more time to ingest blood from anesthetized mice in the 2^nd and 3^rd weeks post-infection, and also longer overall blood-feeding times in the 3^rd week post-infection, when females were around 20 days old. Often, infected Ae. aegypti females did not lay eggs and when they were laid, smaller number of eggs were laid compared to uninfected controls. A reduction in the number of eggs laid per female was evident starting on the 3^rd week post-infection. DENV-2 negatively affected mosquito lifespan, since overall the longevity of infected females was halved compared to that of the uninfected control group.

Conclusions

The DENV-2 strain tested significantly affected Ae. aegypti traits directly correlated with vectorial capacity or mosquito population density, such as feeding behavior, survival, fecundity and oviposition success. Infected mosquitoes spent more time ingesting blood, had reduced lifespan, laid eggs less frequently, and when they did lay eggs, the clutches were smaller than uninfected mosquitoes.     

A network-patch methodology for adapting agent-based models for directly transmitted disease to mosquito-borne disease

Mosquito-borne diseases cause significant public health burden and are widely re-emerging or emerging. Understanding, predicting, and mitigating the spread of mosquito-borne disease in diverse populations and geographies are ongoing modelling challenges. We propose a hybrid network-patch model for the spread of mosquito-borne pathogens that accounts for individual movement through mosquito habitats, extending the capabilities of existing agent-based models (ABMs) to include vector-borne diseases. The ABM are coupled with differential equations representing ‘clouds’ of mosquitoes in patches accounting for mosquito ecology. We adapted an ABM for humans using this method and investigated the importance of heterogeneity in pathogen spread, motivating the utility of models of individual behaviour. We observed that the final epidemic size is greater in patch models with a high risk patch frequently visited than in a homogeneous model. Our hybrid model quantifies the importance of the heterogeneity in the spread of mosquito-borne pathogens, guiding mitigation strategies.     

Mosquitoes of Western Yunnan Province,China: Seasonal Abundance,Diversity, and Arbovirus Associations

Objective

The western borderland between Yunnan Province, China, and Myanmar is characterized by a climate that facilitates year-round production of mosquitoes. Numerous mosquito-transmitted viruses, including Japanese encephalitis virus circulate in this area. This project was to describe seasonal patterns in mosquito species abundance and arbovirus activity in the mosquito populations.

Methods

Mosquitoes were collected in Mangshi and Ruili cities of Dehong Prefecture near the border of China and Burma in Yunnan Province, the Peoples Republic of China in 2010. We monitored mosquito species abundance for a 12-month period using ultraviolet light, carbon dioxide baited CDC light and gravid traps; and tested the captured mosquitoes for the presence of virus to evaluate mosquito-virus associations in rural/agricultural settings in the area.

Results

A total of 43 species of mosquitoes from seven genera were collected, including 15 Culex species, 15 Anopheles spp., four Aedes spp., three Armigeres spp., one Mimomyia spp., two Uranotaenia spp. and three Mansonia spp.. Species richness and diversity varied between Mangshi and Ruili. Culex tritaeniorhynchus, Culex quinquefasciatus, Anopheles sinensis and Anopheles peditaeniatus were the most abundant species in both sampling sites. Ultraviolet light traps collected more specimens than CDC light traps baited with dry ice, though both collected the same variety of mosquito species. The CDC gravid trap was the most effective trap for capture of Culex quinquefasciatus, a species underrepresented in light trap collections. A total of 26 virus strains were isolated, which included 13 strains of Japanese encephalitis virus, four strains of Getah virus, one strain of Oya virus, one strain from the orbivirus genus, and seven strains of Culex pipien pallens densovirus.

Conclusions

The present study illustrates the value of monitoring mosquito populations and mosquito-transmitted viruses year-round in areas where the climate supports year-round adult mosquito activity.     

Non-larvicidal effects of Bacillus thuringiensis israelensis and Bacillus sphaericus on oviposition and adult mortality of Culex quinquefasciatus Say (Diptera: Culicidae).

Two microbial mosquito larvicides, Bacillus thuringiensis ssp. israelensis (Bti) and Bacillus sphaericus (Bsph), have been shown to be highly effective in controlling mosquito larvae and have been used in larvicidal programs for many years. In exploring other modes of action of these agents, we studied the ovipositional response of Bsph susceptible and resistant Culex quinquefasciatus to aqueous suspensions of Bti and Bsph water dispersible granules (WDG). We quantified the level of mortality of adult mosquitoes caused by exposure to Bti and Bsph suspensions during oviposition. Significantly lower numbers of egg rafts were laid and collected from the treatments than the control regimen. There was an inverse relationship between Bacillus product concentrations and oviposition. As the concentration of Bti or Bsph increased from 0.0 to 2.0 mg/L, treated waters received progressively fewer egg rafts. In addition to the negative effects of Bacillus on oviposition, both male and female adult mosquitoes suffered high mortality on landing and imbibing on Bti and Bsph suspensions, the extent of mortality directly proportional to concentration. These two microbial agents used solely as mosquito larvicides thus have the additional benefits of reducing mosquito oviposition and killing adult mosquitoes, especially gravid females that come in contact with the treated water either for oviposition or drinking. Reducing the number of gravid females may also result in reduced transmission rates of pathogens. The combined effects of reduced oviposition and adult mortality could result in higher control potential of these microbial agents.     

Mosquito-only flaviviruses,isolated from <Emphasis Type="Italic">Aedes albopictus</Emphasis> in Slovenia: results of a pilot mosquito monitoring program

Autochthonous transmissions of mosquito-borne diseases were described in close proximity to Slovenia where the knowledge of mosquito species and the viruses they transmit remains very scarce. Therefore we aimed to assess the burden mosquitoes bring to the local community and to test mosquitoes for the presence of the selected zoonotic arboviruses, i. e. Dengue (DENV), West Nile (WNV) and Chikungunya (CHIKV). A pilot mosquito monitoring was conducted in 2012 within two municipalities based on adult mosquito trapping. Altogether 2007 adult mosquitoes were caught. Females of Aedes albopictus and Culex pipiens represented the majority of the total mosquito catch. In sites with more households and nearby greenery, catches of Ae. albopictus were more abundant. Highest numbers of Cx. pipiens females were caught close to a nature reserve, where many bird species stop during their migrations. Trapping results are consistent with both species’ feeding behaviour. Female mosquitoes were grouped into 58 pools according to species, location and date of catch. Real time RT-PCRs for WNV, DENV and CHIKV were performed, but no arboviral genomes were detected in any of the tested mosquito pools. However, amplicons were obtained in three pools when using generic RT-PCR markers for flaviviruses. The viruses detected were propagated and isolated in mosquito cell line C3/36 and identified with sequencing as mosquito-only flaviviruses (MOFs). The important contributions of this study are a successful first isolation of MOFs and confirmation of the presence of the invasive mosquito Ae. albopictus in Slovenia.     

Mosquito traps designed to capture Aedes aegypti (Diptera: Culicidae) females: preliminary comparison of Adultrap, MosquiTRAP and backpack aspirator efficiency in a dengue-endemic area of Brazil

In this report, the efficiency of Adultrap under field conditions is compared to a CDC backpack aspirator and to MosquiTRAP. An urban dengue-endemic area of Rio de Janeiro was selected to evaluate the efficiency of mosquito traps in capturing Aedes aegypti females. Adultrap and aspirator captured similar numbers of Ae. aegypti females, with the former showing high specificity to gravid individuals (93.6%). A subsequent mark-release-recapture experiment was conducted to evaluate Adultrap and MosquiTRAP efficiency concomitantly. With a 6.34% recapture rate, MosquiTRAP captured a higher mean number of female Ae. aegypti per trap than Adultrap (chi2 = 14.26; df = 1; p < 0,05). However, some MosquiTRAPs (28.12%) contained immature Ae. aegypti after 18 days of exposure in the field and could be pointed as an oviposition site for female mosquitoes. Both trapping methods, designed to collect gravid Ae. aegypti females, seem to be efficient, reliable and may aid routine Ae. aegypti surveillance.     

Pooled PCR testing strategy and prevalence estimation of submicroscopic infections using Bayesian latent class models in pregnant women receiving intermittent preventive treatment at Machinga District Hospital,Malawi, 2010

Background

Metarhizium anisopliae is a naturally occurring fungal pathogen of mosquitoes. Recently, Metarhizium has been engineered to act against malaria by directly killing the disease agent within mosquito vectors and also effectively blocking onward transmission. It has been proposed that efforts should be made to minimize the virulence of the fungal pathogen, in order to slow the development of resistant mosquitoes following an actual deployment.

Results

Two mathematical models were developed and analysed to examine the efficacy of the fungal pathogen. It was found that, in many plausible scenarios, the best effects are achieved with a reduced or minimal pathogen virulence, even if the likelihood of resistance to the fungus is negligible. The results for both models depend on the interplay between two main effects: the ability of the fungus to reduce the mosquito population, and the ability of fungus‐infected mosquitoes to compete for resources with non‐fungus‐infected mosquitoes.

Conclusions

The results indicate that there is no obvious choice of virulence for engineered Metarhizium or similar pathogens, and that all available information regarding the population ecology of the combined mosquito‐fungus system should be carefully considered. The models provide a basic framework for examination of anti‐malarial mosquito pathogens that should be extended and improved as new laboratory and field data become available.