Vector Population Dynamics Research Articles

Analysis of the interrelationship between precipitation and confirmed dengue cases in the city of Recife (Brazil) covering climate and public health information.

Large-scale epidemics of arboviruses, such as dengue, have heightened societal awareness regarding the necessity of combating the primary transmission vectors. Equally critical is the identification of environmental conditions and variables that influence vector population dynamics. Aedes aegypti, the primary vector of arboviruses such as dengue and Zika in Brazil, is closely associated with the climatic and geographical conditions of urban environments. This study examines the relationship between precipitation and confirmed dengue cases in Recife (Brazil), employing regression and quantile analyses to evaluate the influence of meteorological conditions on the disease's spread. The findings reveal a direct correlation between monthly averages of precipitation and confirmed cases, although this is apparent only when excluding years of epidemic peaks. The highest number of cases generally aligns with the rainy season, and the lowest with the dry season, with weak, moderate and strong precipitation events being closely linked to increased dengue incidence. However, notable discrepancies were identified: four out of six major outbreaks occurred in drier months, challenging the assumption of a straightforward relationship between rainfall and dengue incidence. These findings underscore the multifaceted nature of dengue dynamics, suggesting that while precipitation plays a significant role, other factors, including serotype circulation and broader climatic phenomena, are equally critical in driving outbreaks. This complexity highlights the need for a more comprehensive understanding of the mechanisms influencing dengue epidemics.

Dengue-mediated changes in the vectorial capacity of Aedes aegypti (Diptera: Culicidae): manipulation of transmission or infection by-product?

An arthropod's vectorial capacity summarizes its disease transmission potential. Life-history traits, such as fecundity or survival, and behavioral traits, such as locomotor activity, host-seeking and feeding behavior, are important components of vectorial capacity. Studies have shown that mosquito-borne pathogens may alter important vectorial capacity traits of their mosquito vectors, thus directly impacting their transmission and epidemic potential. Here, we compile and discuss the evidence supporting dengue-mediated changes in the yellow fever mosquito Aedes aegypti (L.), its primary vector, and evaluate whether the observed effects represent an evolved trait manipulation with epidemiological implications. Dengue infection appears to manipulate essential traits that facilitate vector-host contact, such as locomotor activity, host-seeking, and feeding behavior, but the underlying mechanisms are still not understood. Conversely, life-history traits relevant to vector population dynamics, such as survival, oviposition, and fecundity, appear to be negatively impacted by dengue virus. Overall, any detrimental effects on life-history traits may be a negligible cost derived from the virulence that dengue has evolved to facilitate its transmission by manipulating Ae. aegypti behavior and feeding performance. However, methodological disparities among studies render comparisons difficult and limit the ability to reach well-supported conclusions. This highlights the need for more standardized methods for the research into changes in virus-mediated traits. Eventually, we argue that the effects on life-history traits and behavior outlined here must be considered when assessing the epidemiological impact of dengue or other arbovirus-vector-host interactions.

Population Dynamics of Potential Insect Vectors of Xylella fastidiosa (Xanthomanadales: Xanthomonadaceae) and Other Auchenorrhyncha in Olive and Citrus Groves of Crete, Greece

This study investigated the phenology and population dynamics of potential insect vectors of Xylella fastidiosa Wells et al. and other Auchenorrhyncha species in olive and citrus groves of Chania province, Crete, Greece. Although X. fastidiosa has not been reported in Greece, its introduction could cause serious diseases in many crops, including olives and citrus. Olive groves of Olea europaea L. ‘Koroneiki’ were sampled systematically using sweep net and Malaise traps over 24 months. One citrus grove was sampled for one year using a Malaise trap. Sweep net samples were taken from the herbaceous cover, tree canopy, and field borders of olive groves. Auchenorrhyncha were more abundant on the herbaceous cover compared to the canopy and field margins. Aphrophoridae species were mostly found on the herbaceous cover and in low numbers during fall (October–December) and spring (April–May). Cicadellidae species, such as Euscelis spp., were frequently found on the herbaceous cover of both olive and citrus groves. One Aphrophoridae and several Cicadellidae species were recorded in the citrus grove. Altitude was found to influence the population abundance of some Auchenorrhyncha species in olive groves. These results provide information for effective integrated management of insect vectors and their vector-borne pathogens.

Seasonal species composition, abundance and public health importance of mosquito vectors (Diptera: Culicidae) in Huai Tha Khoei Reservoir, Ratchaburi, Thailand

Abstract. Chaiphongpachara T, Laojuna S. 2024. Seasonal species composition, abundance and public health importance of mosquito vectors (Diptera: Culicidae) in Huai Tha Khoei Reservoir, Ratchaburi, Thailand. Biodiversitas 25: 1264-1275. Mosquitoes are vectors for pathogens that cause life-threatening diseases in humans and animals. Significant mosquito-borne diseases include malaria, dengue, chikungunya, Zika, Japanese encephalitis, and filariasis. Anthropogenic environmental changes can significantly impact the dynamics of disease vector populations, which can lead to outbreaks of mosquito-borne diseases. This study investigated the seasonal variation in species composition and abundance of mosquito vectors around the Huai Tha Khoei Reservoir in Ratchaburi Province, Thailand, across cool, hot, and rainy seasons. A total of 1363 mosquitoes, representing 30 species from five genera, were collected. In particular, 25 of these species, accounting for 83.33% of the total, were identified as vectors of human pathogens. The most dominant species across all seasons was Culex tritaeniorhynchus Giles 1901, representing 39.47% (n=538) of the total, followed by Anopheles barbirostris Wulp 1884 s.l. (14.38%, n = 196) and Culex vishnui Theobald 1901 (9.02%, n=123). The Shannon diversity index was highest during the rainy season (H’= 2.144) and lowest in the hot season (H’=1.788). This is consistent with the results of the UPGMA tree based on beta diversity, indicating that mosquito diversity in the rainy season differs significantly from that in the cool and hot seasons. The findings enhance our understanding of the impact of seasonality on mosquito vectors in this region, which is crucial for developing effective disease control strategies. Additionally, this study serves as a valuable reference for understanding the diversity of mosquito vectors in other areas.

Anopheles aquatic development kinetic and adults’ longevity through different seasons in laboratory and semi-field conditions in Burkina Faso

AbstractBackgroundAnopheles mosquitoes are ectothermic and involved in numerous pathogen transmissions. Their life history traits are influenced by several environmental factors such as temperature, relative humidity and photoperiodicity. Despite extensive investigations of these environmental conditions on vector population ecology, their impact on the different life stages of Anopheles at different seasons in the year remains poorly explored. This study reports the potential impact of these abiotic factors on the immature and adult stages of Anopheles gambiae sensu lato during different seasons.MethodsEnvironmental conditions were simulated in the laboratory using incubators to mimic the environmental conditions of two important periods of the year in Burkina Faso: the peak of rainy season (August) and the onset of dry season (December). Eggs from wild An. coluzzii and An. gambiae s.l. were reared separately under each environmental condition. For Anopheles coluzzii or An. gambiae s.l., eggs were equally divided into two groups assigned to the two experimental conditions. Four replicates were carried out for this experiment. Then, egg hatching rate, pupation rate, larval development time, larva-to-pupae development time, adult emergence dynamics and longevity of Anopheles were evaluated. Also, pupae-to-adult development time from wild L3 and L4 Anopheles larvae was estimated under semi-field conditions in December.ResultsA better egg hatching rate was recorded overall with conditions mimicking the onset of the dry season compared to the peak of the rainy season. Larval development time and longevity of An. gambiae s.l. female were significantly longer at the onset of the dry season compared than at the peak of the rainy season. Adult emergence was spread over 48 and 96 h at the peak of the rainy season and onset of dry season conditions respectively. This 96h duration in the controlled conditions of December was also observed in the semi-field conditions in December.ConclusionsThe impact of temperature and relative humidity on immature stages and longevity of An. gambiae s.l. adult females differed under both conditions. These findings contribute to a better understanding of vector population dynamics throughout different seasons of the year and may facilitate tailoring of control strategies.Graphical

Impacts of Changing Climate on Arthropod Vectors and Diseases Transmission

Climate change stands as a burgeoning global concern with profound implications. The present review seeks to present the projected impacts of climate change on disease vectors and their transmission of various human and animal diseases. The impact of climate on the prevalence of vector-borne diseases (VBDs), which significantly affect human and animal populations, is notable. The occurrence of VBDs, influenced by local epidemiological and ecological factors alongside specific climatic conditions, may exhibit fluctuations due to climate change. Particularly affected are exothermic arthropod vectors, responsible for transmitting most vectorborne diseases. The intricate interplay of temperature, precipitation, humidity, and other environmental factors significantly shapes the reproduction, development, behavior, and population dynamics of arthropod disease vectors. Also, climate change can alter the spread of pathogens within vectors, influence population dynamics, and impact the range of nonhuman vertebrate reservoirs for numerous vector-borne diseases. Predicting the precise impact of sustained climate change on these diseases poses a considerable challenge, necessitating comprehensive long-term research. These researches must encompass the effects of climate change while considering the contributions of other global change agents, including increased trade and travel, demographic shifts, civil unrests, alterations in land use, water availability, and related factors. The association between climate change and the emergence of specific diseases has been established. However, for certain diseases, the risk of local transmission is significant, while for others, pinpointing the exact influence remains elusive. Therefore, strategic adaptation and preparedness for the shifting distribution patterns of VBDs are imperative, especially in the context of Nigeria and Africa as a whole.

IxPopDyMod: an R package to write, run, and analyze tick population and infection dynamics models

Given the increasing prevalence of tick-borne diseases, such as Lyme disease, modeling the population and infection dynamics of tick vectors is an important public health tool. These models have applications for testing the effects of control methods or climate change on tick populations. There is an established history of tick population models, but code for them is rarely shared, especially not in a convenient format for others to modify and use. We present an R package, called IxPopDyMod, intended to function as a flexible and consistent framework for reproducible Ixodidae (hard-bodied ticks) population dynamics models. Here we focus on two key parts of the package: a function to create valid model configurations and a function to run a configured model and return the daily population over time. We provide three examples in appendices: one reproducing an existing Ixodes scapularis population model, one providing a novel Dermacentor albipictus model, and one showing Borrelia burgdorferi infection in ticks. Together these examples show the flexibility of the package to model scenarios of interest to tick researches.Graphical

Multiscale malaria models and their uniform in-time asymptotic analysis

In this paper, we show that an extension of the classical Tikhonov–Fenichel asymptotic procedure applied to multiscale models of vector-borne diseases, with time scales determined by the dynamics of human and vector populations, yields a simplified model approximating the original one in a consistent, and uniform for large times, way. Furthermore, we construct a higher-order approximation based on the classical Chapman–Enskog procedure of kinetic theory and show, in particular, that it is equivalent to the dynamics on the first-order approximation of the slow manifold in the Fenichel theory.

Epidemiology and Diagnostics of Cacao Swollen Shoot Disease in Ghana: Past Research Achievements and Knowledge Gaps to Guide Future Research.

Cacao swollen shoot disease (CSSD) caused by complexes of cacao swollen shoot badnaviruses (family Caulimoviridae, genus Badnavirus) remains highly prevalent and devastating in West Africa. The disease continues to impact substantially on cacao yield loss, cacao tree mortality, and decline in foreign exchange income from cacao bean sales. Currently, the disease is estimated to have a prevalence rate of over 30% in Ghana, as assessed in the ongoing third country-wide surveillance program. Although achievements from past research interventions have greatly elucidated the etiology, biology, epidemiology, diagnostics, and management of the disease, there are some outstanding knowledge gaps. The role of these information gaps and their effect on CSSD epidemiology and prevalence remain unanswered. This paper summarizes existing scientific knowledge from past research achievements that have provided elucidation on CSSD epidemiology, management options, and guided future research. The discussion highlights the need for multidisciplinary research with modern tools and institutional collaborators to holistically bring clarity on knowledge gaps on pathogen biology, virus-host--vector interactions, role of environmental and soil nutrient effects on CSSD severity, evolution pattern, role of alternative hosts on virus species diversity, vector population dynamics, and their overall impact on CSSD prevalence and integrated management in cacao plantations.

Bioecological traits of spittlebugs and their implications on the epidemiology and control of Xylella fastidiosa epidemic in Apulia (Southern Italy).

Spatial-temporal dynamics of spittlebug populations, together with transmission biology, are of major importance to outline the disease epidemiology of Xylella fastidiosa (Xf) subsp. pauca in Apulian olive groves. The spread rate of Xf is mainly influenced by (i) the pathogen colonization of the host plant; (ii) the acquisition of the pathogen by the vector from an infected plant, and its inoculation to healthy plants; (iii) the vector population dynamics and abundance at different spatial scales; (iv) the dispersal of the vector. In this contribution we summarize the recent advances in research on insect vectors' traits - points (ii), (iii), (iv) - focusing on those most relevant to Xf epidemic in Apulia. Among the vectors' bioecological traits influencing Xf epidemic on olive trees, we emphasize: natural infectivity and transmission efficiency, phenological timing of both nymphal and adult stage, the role of semi-natural vegetation as vectors' reservoir in the agroecosystem and landscape, preferential and directional dispersal capabilities. Despite the research on Xf vectors carried out in Europe in the last decade, key uncertainties on insect vectors remain, hampering a thorough understanding of pathogen epidemiology and the development of effective and targeted management strategies. Our goal is to provide a structured and contextualized review of knowledge on Xf vectors' key traits in Apulian epidemic, highlighting information gaps and stimulating novel research pathways on Xf pathosystems in Europe.

Evaluate the population development of green leafhopper as a tungro vector in the endemic area from long-term data

The epidemiological aspect including monitoring is a critical component of implementing an early warning system. The tungro epidemic in rice is influenced by the population dynamics of the green leafhopper vector. Likewise, rainfall and biotic factors affect the abundance of green leafhopper vectors. Long-term data are essential to explain that mechanism, so population predictions on a seasonal scale can be obtained accurately. This paper analyses weekly data on catching green leafhoppers and other arthropods in a continuous cropping system from 2013-2019. We utilize the climatic data gathered to assess the impact of climatic conditions on population dynamics. To improve the additive and homoscedasticity of the time series, we transform the data. The data are fitted in a linear model. The results showed that the green leafhopper population affected the incidence of tungro in the field. From January to December, the population dynamics of the green leafhopper can be characterized. It can assist in monthly population forecasting for the following years. Exogenous and endogenous variables, however, still need to be studied more comprehensively to identify any other predictive components that should be incorporated.

Manure and mosquitoes: life history traits of two malaria vector species enhanced by larval exposure to cow dung, whilst chicken dung has a strong negative effect

BackgroundMalaria vectors have a strong ecological association with rice agroecosystems, which can provide abundant aquatic habitats for larval development. Climate-adapted rice cultivation practices, such as the System of Rice Intensification (SRI), are gaining popularity in malaria-endemic countries seeking to expand rice production; however, the potential impact of these practices on vector populations has not been well characterised. In particular, SRI encourages the use of organic fertilisers (OFs), such as animal manures, as low-cost and environmentally friendly alternatives to industrially produced inorganic fertilisers. We therefore set out to understand the effects of two common manure-based OFs on the life history traits of two major African malaria vectors, Anopheles arabiensis and Anopheles gambiae sensu stricto (s.s.).MethodsLarvae of An. arabiensis and An. gambiae s.s. were reared from first instar to emergence in water containing either cow or chicken dung at one of four concentrations (0.25, 0.5, 0.75, and 1.0 g/100 ml), or in a clean water control. Their life history traits were recorded, including survival, development rate, adult production, and adult wing length.ResultsExposure to cow dung significantly increased the development rate of An. gambiae s.s. independent of concentration, but did not affect the overall survival and adult production of either species. Chicken dung, however, significantly reduced survival and adult production in both species, with a greater effect as concentration increased. Interestingly, An. arabiensis exhibited a relative tolerance to the lowest chicken dung concentration, in that survival was unaffected and adult production was not reduced to the same extent as in An. gambiae s.s. The effects of chicken dung on development rate were less clear in both species owing to high larval mortality overall, though there was some indication that it may reduce development rate. Adult wing lengths in males and females increased with higher concentrations of both cow and chicken dung.ConclusionsOur findings suggest that manure-based OFs significantly alter the life history traits of An. gambiae s.s. and An. arabiensis. In both species, exposure to cow dung may improve fitness, whereas exposure to chicken dung may reduce it. These findings have implications for understanding vector population dynamics in rice agroecosystems and may inform the use of OFs in SRI, and rice agriculture more widely, to avoid their adverse effects in enhancing vector fitness.Graphical

An eco-epidemiological model supporting rational disease management of Xylella fastidiosa. An application to the outbreak in Apulia (Italy)

Knowledge on the dynamics of Xylella fastidiosa infection is an essential element for the effective management of new foci. In this study, we propose an Eco-epidemiological Model (XEM) describing the infection dynamics of X. fastidiosa outbreaks. XEM can be applied to design disease management strategies and compare their level of efficacy. XEM is a spatial explicit mechanistic model for short-range spread of X. fastidiosa considering: i) the growth of the bacterium in the host plant, ii) the acquisition of the pathogen by the vector and its transmission to host plants, iii) the vector population dynamics, iv) the dispersal of the vector. The model is parametrized based on data acquired on the spread of X. fastidiosa subsp. pauca in olive groves in the Apulia region. Four epidemiological scenarios were considered combining host susceptibility and vector abundance. Eight management strategies were compared testing several levels of vector control efficacy, plant cutting radius, time to detection and intervention. Simulation results showed that the abundance of the vector is the key factor determining the spread rate of the pathogen. Vector control efficacy and time to detection and intervention emerged as the key factors for an effective eradication strategy. XEM proved to be a suitable tool to support decision making for the drafting and management of emergency plans related to new outbreaks.

Cambio climático y enfermedades transmitidas por vectores. Convertir el conocimiento en acción

Andalusia is particularly sensitive to climate change, not only because of extreme weather events, but also because of the impact on the population dynamics of vectors, pathogens, reservoirs and hosts, which has led to a change in the epidemiological patterns of vector-borne diseases. In order to achieve an integrated vector management for disease control, public action is necessary. This study describes the design of the initial phase of a strategy for knowledge translation about climate change and vector-borne diseases to the public, using transdisciplinary co-creation and the World Café participatory method with three discussion rounds to address strategies for three age groups (adults, adolescents and schoolchildren). The aim is to drive knowledge into action and for this purpose the underlying messages for action (strategic and instrumental) have been identified, as well as the formats of the knowledge products and the potential implementers of the strategies.

Spatio-Temporal Distribution and Species Composition of Malaria Mosquitoes in Selected Districts of Benishangul Gumuz Regional State, Western Ethiopia

The highest malaria transmission risk as stratified by annual parasite incidence, appears largely in Benishangul Gumuz region, the lowland and midlands of the western border with Sudan and South Sudan. The effectiveness of malaria vector control strategy depends on knowledge of factors that determine vector density and distribution, affecting adult Anopheles vector population dynamics and malaria transmission. This study aimed to investigate the spatial-temporal distribution and species composition of Anopheles mosquitos in western Ethiopia. The study was conducted in three districts of Assosa Zone (Assosa, Homosha and Bambasi), Benishangul Gumuz regional state. Adult and larva of Anopheles mosquitoes were collected using standard techniques after the long rainy season (October 2020-December 2020) and Dry season (January to February 2021). After collection, the data were analyzed using SPSS software. A total of 2063 Anopheles mosquitoes (1745 larvae and 318 adults) were collected during the study period and categorized into five Anopheles species (An. gambiae, An. funestus, An. coustani, An. ziemanni, and An. squamosus). Among all species An. gambiae s.l. (1548, 88.7%) was the predominant species while An. squamous (14, 0.8%) was the least dominant. From the three districts, the highest Anopheles mosquito specimens were collected from Bambasi (917, 52.6% larval and 126, 39.6% adult). And out of all collection months, the highest number of larvae and adult mosquitoes was collected during October. Among larval breeding habitats, pond was highly productive for Anopheles mosquitoes. Anopheles mosquitoes prefer to breed in all breeding sites, particularly temporary and sunlit habitats. Anopheles gambiae s.l. predominantly occurs during all seasons in its immature and mature stages, suggesting that malaria is a health problem in the area.

Status of Onchocerca volvulus (Spirurida: Onchocercidae) Transmission and Effect of Climatic Variables on the Vector Population Dynamics After Two Decades of Ivermectin-based Preventive Chemotherapy in the Mbam Valley (Centre Region, Cameroon).

Entomological indicators of onchocerciasis transmission and the effect of climatic variables on the vector population dynamics were investigated in two first-line villages after more than two decades of mass drug administration with ivermectin. Female blackflies were collected in two villages (Bayomen and Biatsota) using human landing method for a period of 12 months. Blackflies were dissected and entomological indices were computed. Monthly temperature, precipitation, and humidity were collected and the Spearman correlation rank test was used to assess the relationship between biting rates and climatic variables. The highest biting rates (62,280 bites/human/month in Bayomen and 42,090 bites/human/month in Biatsota) were recorded during the long rainy season (November). The Onchocerca volvulus transmission was greater during the long dry season in both villages, with a peak at the beginning of the long dry season in Biatsota (100 infective larvae/human/month), and at the middle of the long dry season in Bayomen (92 infective larvae/human/month). No correlation was found between biting rates and selected climatic variables in the two villages. This study revealed that onchocerciasis transmission is ongoing in the study area despite almost 25 years of Community-Directed Treatment with Ivermectin. In accordance with WHO recommendations, vector control should be used in combination with mass drug administration to accelerate transmission interruption of onchocerciasis. To be optimal, this vector control should be implemented during the long dry season (November to March) when water volumes are low and transmission potentials are high.

Abundance of Lutzomyia longipalpis and Nyssomyia whitmani, the Leishmania spp. vectors in northeastern of Argentina: Are spatial and temporal changing patterns consistence?

Lutzomyia longipalpis and Nyssomyia whitmani were incriminated as vectors of Leishmania sp. Spatial heterogeneity together with seasonal changes in abundance constitute important elements for the understanding of the dynamics of vector populations, and there are fundamental for the development of adequate prevention and control strategies. The aim of this work was to compare the spatial and seasonal abundance of Lu. longipalpis and Ny. whitmani at a city spatial scale between two periods separated by three years. To study the spatial distribution, we compared the abundance distribution of these species at two warm times, 2011 with 2014. Respect to inter-annual seasonal abundance changes, we compared the four seasons of the year between two periods (2011–2012 vs 2014–2016). The spatial distribution for both species were found to be distributed mainly in the same areas of the city in both periods. We change for: Respect to the seasonal pattern of abundance, we observed that seasonal patterns showed changes between periods. Our study defines the ‘where’ and ‘when’ implement the actions to mitigate leishmaniasis cases.

Control strategies in the spatial population dynamics of Aedes aegypti vector using sterile mosquitoes and insecticides

In this work, we analyze the population dynamics of the Aedes aegypti mosquito, a transmitter of various viruses such as dengue, zika, and chikungunya, in a given area, based on the use of various control techniques. To do this, we use a reaction-diffusion model that considers various environmental characteristics such as temperature and landscape shape. Initially, we do this analysis using larvicides, insecticides, and the SIT (sterile insect release) technique separately. We simulate different control scenarios using appropriate numerical methods, test combinations of these techniques, and determine the efficiency of each strategy according to the overall reduction in the number of fertilized females due to the applied technique. Subsequently, through a cost-effectiveness analysis, we verified that the release of sterile mosquitoes at the beginning of each seasonal period is the best strategy to control the population of Aedes aegypti.

Using Bayesian state-space models to understand the population dynamics of the dominant malaria vector, Anopheles funestus in rural Tanzania

BackgroundIt is often assumed that the population dynamics of the malaria vector Anopheles funestus, its role in malaria transmission and the way it responds to interventions are similar to the more elaborately characterized Anopheles gambiae. However, An. funestus has several unique ecological features that could generate distinct transmission dynamics and responsiveness to interventions. The objectives of this work were to develop a model which will: (1) reconstruct the population dynamics, survival, and fecundity of wild An. funestus populations in southern Tanzania, (2) quantify impacts of density dependence on the dynamics, and (3) assess seasonal fluctuations in An. funestus demography. Through quantifying the population dynamics of An. funestus, this model will enable analysis of how their stability and response to interventions may differ from that of An. gambiae sensu lato.MethodsA Bayesian State Space Model (SSM) based on mosquito life history was fit to time series data on the abundance of female An. funestus sensu stricto collected over 2 years in southern Tanzania. Prior values of fitness and demography were incorporated from empirical data on larval development, adult survival and fecundity from laboratory-reared first generation progeny of wild caught An. funestus. The model was structured to allow larval and adult fitness traits to vary seasonally in response to environmental covariates (i.e. temperature and rainfall), and for density dependency in larvae. The effects of density dependence and seasonality were measured through counterfactual examination of model fit with or without these covariates.ResultsThe model accurately reconstructed the seasonal population dynamics of An. funestus and generated biologically-plausible values of their survival larval, development and fecundity in the wild. This model suggests that An. funestus survival and fecundity annual pattern was highly variable across the year, but did not show consistent seasonal trends either rainfall or temperature. While the model fit was somewhat improved by inclusion of density dependence, this was a relatively minor effect and suggests that this process is not as important for An. funestus as it is for An. gambiae populations.ConclusionThe model's ability to accurately reconstruct the dynamics and demography of An. funestus could potentially be useful in simulating the response of these populations to vector control techniques deployed separately or in combination. The observed and simulated dynamics also suggests that An. funestus could be playing a role in year-round malaria transmission, with any apparent seasonality attributed to other vector species.

The Establishment and Spread of a Newly Introduced Begomovirus in a Dry Tropical Environment Using Tomato Yellow Leaf Curl Virus as a Case Study.

Early detection of tomato yellow leaf curl virus (TYLCV) in a previously unaffected tomato production district in Australia allowed its spread to be evaluated spatially and temporally. The population dynamics of the TYLCV vector, Bemisia argentifolii (silverleaf whitefly, SLW), were also evaluated. The district is a dry tropical environment with a clear break to commercial production during the summer wet season. The incidence of TYLCV within crops and its prevalence through the district was influenced by weather, location, vector movements, and the use of Ty-1 virus-resistant hybrids. Rainfall had an important influence, with late summer and early autumn rain suppressing the levels of SLW and, by contrast, a dry summer supporting faster population growth. The use of Ty-1 hybrids appears to have reduced the incidence of TYLCV in this district. There was limited use of Ty-1 hybrids during 2013, and by season end, crops had moderate levels of SLW and high virus incidence. The 2015 and early 2016 season had high SLW populations, but TYLCV incidence was lower than in 2013, possibly due to the widespread adoption of the Ty-1 hybrids reducing virus spread. This study provides valuable epidemiology data for future incursions of begomoviruses, and other viruses spread by SLW.