Vector Abundance Research Articles

Impact of urbanization on the abundance and distribution of Anophelines population in Ghaziabad district, Uttar Pradesh, India.

In urban areas, upsurge in population has resulted in more breeding sites for malaria vectors, and hence this scenario potentially undermine malaria elimination and control programs. The change in land use due to urbanization may result in the presence and distribution of malaria vectors. Understanding potential malaria vectors is essential for current and future malaria transmission control strategies. This study investigated the effects of rapid urbanization on malaria vectors An. culicifacies s.l. and An. stephensi L. in Ghaziabad district. Ghaziabad district which presents several levels of urbanization was selected for this study. Entomological investigations were conducted seasonally from 2014-2016 in the rural, urban, and peri-urban regions. Vector incrimination study was done using ELISA (confirmation by PCR) on suspected Anopheles vectors viz. An. culicifacies, An. stephensi, An. annularis and An. subpictus. An. culicifacies showed alteration in distribution influenced by rural and agricultural land whereas An. stephensi was found to be influenced by artificial habitats and population growth. The study also confirms the association between the abundance of malaria vectors and land use change.

Spatio-temporal patterns of stomoxyine flies (Diptera: Muscidae) in a forested area of Thailand.

Understanding the distribution patterns of vector populations is crucial for comprehending the dynamics of vector-borne diseases. However, data on vector composition and abundance in areas of forest and wildlife-human interface in Thailand remain limited. This research aimed to investigate the spatio-temporal distribution and species diversity of stomoxyine flies (Diptera: Muscidae) in Salakpra Wildlife Sanctuary, Thailand's first wildlife sanctuary. A longitudinal entomological survey was conducted monthly from May 2022 to April 2023 in four habitats: core forest, grassland forest, a wildlife breeding center, and a local cattle farm. A total of 11,256 stomoxyine flies from four genera were captured. Based on morphological keys, nine species of stomoxyine flies were identified: Stomoxys pullus (29.63%), Stomoxys calcitrans (19.65%), Stomoxys indicus (16.09%), Haematostoma austeni (14.23%), Haematobia irritans exigua (8.22%), Haematobosca sanguinolenta (7.96%), Stomoxys uruma (1.98%), Stomoxys sitiens (1.75%), and Stomoxys bengalensis (0.49%). Heterogeneous variations in abundance across months and habitats were observed, in which abundance increased in the rainy season (June-October), exhibiting bimodal peaks at seasonal transitions. Human-disturbed areas, such as the cattle farm, exhibited the highest density and species diversity of stomoxyine flies. In contrast, areas with minimal human disturbance, like core forest, had low diversity and density but supported unique species, like the abundant Haematostoma austeni, which had minor populations in other types of habitats. The results of this study can be integrated into epidemiological models and lay the groundwork for more comprehensive research on vector-borne diseases at the wildlife-livestock interface to mitigate transmission risks and preserve biodiversity.

Trypanosome Infection in Cattle and Associated Vectors in Etang District of Gambella, Ethiopia.

Bovine trypanosomosis produces significant economic losses due to anemia, loss of body condition, and emaciation. The disease is transmitted biologically by tsetse flies and mechanically by biting flies such as Tabanus and Stomoxys. Therefore, this research is aimed at estimating the prevalence of bovine trypanosomosis and the apparent density of its vectors in the Etang Special District. A cross-sectional study was employed from November 2016 to April 2017 for the prevalence and entomological survey. Trypanosoma species were identified using buffy coat and Giemsa staining techniques. Besides, the entomological surveys were conducted using NGU, pyramidal, biconical, and monoconical traps. The vectors were identified to their genus level based on their morphological features like size, color, wing venation, and proboscis. A total of 457 bovine blood samples were collected and tested, of these 16 (3.50%) animals were positive for trypanosomosis. Similarly, 13 T. vivax (81.25%) and 3 T. congolense (18.75%) were the trypanosome species detected. The prevalence in the young (2.56%) and adult (3.99%) age groups was not statistically significant (P > 0.05). However, there were significant (P < 0.05) differences in prevalence between body condition scores, where poor is 6.31%, medium is 1.30%, and good is 0%. Moreover, the difference in mean PCV values between the parasitemic (20.97) and aparasitemic (28.58) groups was statistically significant (P < 0.05). Glossina flies were not found, although 1756 Tabanus and 52 Stomoxys biting flies were gathered. Accordingly, the overall apparent density of Glossina flies was zero (0), with biting flies (20.54) recorded per trap per day. Moreover, the apparent density of Tabanus and 52 Stomoxys was 39.01 and 1.18, respectively. This study confirmed that trypanosomosis and abundant mechanical vectors continue to be problems in the study area, resulting in cattle productivity losses. As a result, strategic management and prevention methods for trypanosomosis and associated vectors should be prioritized. Further investigation of vector needs to be conducted to clear out tsetse presence.

Relative importance of VECTRI model parameters in the malaria disease transmission and prevalence.

In this study, a sensitivity analysis on a VECTRI dynamical model of malaria transmission is investigated to determine the relative importance of model parameters to disease transmission and prevalence. Apart from being most climatic prone, Odisha is a highly endemic state for malaria in India. The lack in sufficient modeling studies severely impacts the malarial process studies which further hinder the possibility of malaria early warning systems and preventive measures to be undertaken beforehand. Therefore, modeling studies and investigating the relationship between malaria transmission process studies and associated climatic factors are the need of the hour. Environmental conditions have pronounced effects on the malaria transmission dynamics and abundance of the poikilothermic vectors, but the exact relationship of sensitivity for these parameters is not well established. Sensitivity analysis is a useful tool for ascertaining model responses to different input variables. Therefore, in order to perform the requisite study, a dynamical model, VECTRI, is utilized. The study period ranges from 2000 to 2013, where several sensitivity tests are performed using different model parameters such as infiltration and evaporation rate loss of ponds, degree-days for parasite development, threshold temperature for parasite development, threshold temperature for egg development in the vector, and maximum and minimum temperature for larvae survival. The experiments suggest that the lower value of minimum temperature for larvae survival (rlarv_tmin), i.e., 16°C, provides higher vector density and entomological inoculation rate (EIR) values. EIR reaches its maximum, when the threshold temperature for parasite development (rtsporo) is 22°C and degree-days for parasite development (dsporo) is 8 degree-days. No change is observed in the vector density; even when rtsporo is 30°C, values of EIR are close to 0. A successive increment of infiltration and evaporation rate loss of ponds (rwaterfrac evap126) values from 130 to 200 mm/day result in approximately 5% consistent decline in vector density and EIR. The study concludes that the most sensitive parameters are dsporo, rlarv_tmin, and rwaterfrac evap126. The VECTRI model is rather insensitive to maximum temperature for larvae survival (rlarv_tmin) for vector density and EIR variables. Further certain modifications and improvements are required in VECTRI to predict out variables like vector density and EIR more accurately in highly endemic region.

A stochastic multi-host model for West Nile virus transmission

When initially introduced into a susceptible population, a disease may die out or result in a major outbreak. We present a Continuous-Time Markov Chain model for enzootic WNV transmission between two avian host species and a single vector, and use multitype branching process theory to determine the probability of disease extinction based upon the type of infected individual initially introducing the disease into the population – an exposed vector, infectious vector, or infectious host of either species. We explore how the likelihood of disease extinction depends on the ability of each host species to transmit WNV, vector biting rates on host species, and the relative abundance of host species, as well as vector abundance. Theoretical predictions are compared to the outcome of stochastic simulations. We find the community composition of hosts and vectors, as well as the means of disease introduction, can greatly affect the probability of disease extinction.

Implications of migratory and exotic birds and the mosquito community on West Nile virus transmission

Background Vector-borne diseases like West Nile virus (WNV) pose a global health challenge, with rising incidence and distribution. Culex mosquitoes are crucial WNV vectors. Avian species composition and bird community diversity, along with vector communities, influence WNV transmission patterns. However, limited knowledge exists on their impact in southwestern Spain, an area with active WNV circulation in wild birds, mosquitoes, and humans. Methods To address this, we conducted a comprehensive study investigating the contributions of migratory and exotic bird species to WNV transmission and the influence of mosquito community composition. Results Analysing 1194 serum samples from 44 avian species, we detected WNV antibodies in 32 samples from 11 species, four for the first time in Europe. Migratory birds had higher WNV exposure likelihood than native and exotic species, and higher phylogenetic diversity in bird communities correlated with lower exposure rates. Moreover, in 5859 female mosquitoes belonging to 12 species, we identified WNV competent vectors like Cx. pipiens s.l. and the Univittatus subgroup. Birds with WNV antibodies were positively associated with competent vector abundance, but negatively with overall mosquito species richness. Conclusions These findings highlight the complex interactions between bird species, their phylogenetics, and mosquito vectors in WNV transmission. Understanding these dynamics will help to implement effective disease control strategies in southwestern Spain.

Genetic characterization of the complete genome of a strain of Chikungunya virus circulating in Brazil

The Chikungunya virus (CHIKV) is a single-stranded positive-sense RNA virus that belongs to the Alphavirus genus of the Togaviridae family. It is primarily transmitted by Aedes aegypti and albopictus mosquitoes. Its genome encodes four non-structural proteins (NSP 1-4) and three structural proteins (C, E1, and E2). Four lineages of this virus have been identified, namely the West African, East African, Central and South African (ECSA), Asian (AL), and Indian Ocean Lineages (IOL). CHIKV is an endemic arbovirus circulating in 51 countries in the Americas. Clinical manifestations attributed to it include high fever, rash, myalgia, and episodes of arthralgia, which subsequently lead to chronic pain and disability, especially in the joints. Sequencing the complete genome of the Chikungunya virus is essential to understand its biology, evolution, and spread and to develop effective strategies for prevention, diagnosis, and treatment. This information is crucial for combating the disease and minimizing its impact on public health. For these reasons, the complete genome of the Chikungunya virus strain br33, identified in the northeastern city of Recife, in the state of Pernambuco, Brazil, was sequenced. The genome has a size of 11,601 nucleotides and contains coding regions for two polyproteins. A phylogenetic analysis indicates that the recent Brazilian strain of CHIKV belongs to the East, Central, and South African lineage (ECSA). This phylogenetic identification is important because this particular genotype has been associated with greater damage and clinical severity. Until 2016, the CHIKV virus was directly associated with travel, and its transmission was limited. Subsequently, the largest outbreak occurred in the state associated with the introduction of a new ECSA lineage, as identified in this study. It is highly likely that new CHIKV outbreaks will occur in the near future due to the abundance of competent vectors in Brazil and a susceptible population, exposing more than 11 million inhabitants to an increasing risk of infection.

Cassava mosaic disease and abundance of its whitefly vector in north-western Democratic Republic of Congo

Cassava mosaic disease (CMD) is rampant in the Democratic Republic of Congo (DRC). The objective of this study was to assess the significance of CMD and abundance of its whitefly (Bemisia tabaci) vector, in the North-Western provinces of the DRC. A field study was conducted in three provinces, namely Mongala, North Ubangi, and South Ubangi, of north-western DRC, during February to March 2022. One hundred cassava (Manihot esculenta Crantz) fields, aged 3 to 9 months and at intervals of about 10 Km apart, were prospected during an epidemiological survey of cassava mosaic disease. The cassava cropping system (pure culture or intercropped), and the epidemiological parameters of cassava mosaic disease (incidence, severity of CMD, abundance of whiteflies, sources of infection) were assessed. Results showed that the prevalence of CMD and abundance of whitefly vectors in DRC were significantly different among the three provinces. The incidence was low in South-Ubangi (16.49%), medium in Mongala (21.83%), and high in North-Ubangi (44.63%). The severity of the disease in north-western DR Congo is very low and remains below level a value of 3 in all the provinces covered by this study. Whitefly abundance fluctuated between 1.49 (South-Ubangi) to 5.74 (Mongala). Infected cuttings were the main source of CMD infection in all the provinces. Cassava cultivated in monoculture had the highest populations of this victory.

Spatiotemporal changes in exposition risk to leishmaniases vector in residences within a fishing tourism area of Pantanal wetland.

Miranda Municipality of Mato Grosso do Sul, borders the Pantanal wetland, a famous fishing destination visited by tourists from all over the world, and is a location where visceral leishmaniasis has been reported. To assess the risk of Leishmania infantum transmission, we studied the sandfly community, focusing on known vector and parasite presence. We conducted light trap collections twice per month at nine sites within the city (including two forested areas) for one year. We collected a total of 12,727 sand flies, 10,891 males and 1,836 females belonging to 11 species: Brumptomyia avellari, Evandromyia aldafalcaoae, Ev. evandroi, Ev. lenti, Ev. sallesi, Ev. walkeri, Lu. longipalpis, Nyssomyia whitmani, Psathyromyia bigeniculata, Pa. hermanlenti and Pa. punctigeniculata. Lutzomyia longipalpis, the proven vector of Leishmania infantum, was captured each month, and was the most abundant species observed, accounting for more than 99% of sand flies captured in most sites, especially where chicken coops were present. Evidence of Leishmania infantum infection was detected in 0.40% of Lu. longipalpis tested. We developed a generalized mixed multilevel model for Lu. longipalpis, that includes within-year seasonality, location of capture (indoors vs. outdoors), vector abundance, and sex ratio. The VL vector was abundant both inside and outside houses. Large numbers of Lu. longipalpis were observed in outdoor sites where domestic animals were present but were absent from forest sites. Our findings suggest high vector populations and Le. infantum presence in a city where tourists could be exposed to visceral leishmaniasis, with significant implications for more surveillance and control activities.

Aedes albopictus distribution in Ibagué, Colombia: Potential risk of arboviral outbreaks

Aedes albopictus is a vector for arboviruses, such as dengue, Zika, chikungunya, and yellow fever. The first A. albopictus reports on the American continent date back to 1985. It has spread rapidly throughout Colombia since its first report in 1998 due to its ecological and physiological adaptation capability. To determine A. albopictus distribution in the 13 communes of Ibagué, Colombia. Samples were collected between May and November 2022 in the 13 communes of Ibagué. Vacuum sampling and sweep-netting entomological nets were used in areas with abundant vegetation. The mosquitoes were transported to the Laboratorio de Investigaciones en Parasitología Tropical at the Universidad del Tolima for taxonomic determination. We identified 708 A. albopictus specimens distributed throughout Ibague’s 13 communes. The highest vector abundance occurred in communes 10, 11, 7, 8, 2, and 9; communes 3, 4, 5, 6, 12, and 13 had a relative abundance of around 3%, while commune 1 had 2% of relative abundance. Aedes albopictus is distributed throughout all the communes of Ibague. Its dispersion has probably been favored by this region’s environmental and social conditions. We recommend annual monitoring of these vectors populations and molecular characterization of the found arboviruses. Ascertaining this mosquito’s distribution throughout the city will enable focusing entomological control strategies and preventing future arbovirus outbreaks.

Leafhoppers as vectors of phytoplasma diseases in Canadian berry crops: a review in the face of climate change

Abstract Climate change has facilitated the introduction, establishment, and movement of invasive species in northern regions, enabling the colonization of previously unsuitable areas. While the responses of insects to these changes have been increasingly studied, our understanding of how such alterations impact trophic interactions still requires further research to make reliable predictions about the spread of diseases in a warming world. Phytoplasmas, a group of obligate parasitic unculturable Mollicutes, primarily rely on leafhoppers (Hemiptera: Cicadellidae) for transmission, spread, and survival. Phytoplasmas are associated with over 600 diseases affecting more than 1,000 plant species, including berries, grapevines, and other small fruits. In North America, diseases such as grapevine yellows, blueberry stunt, and strawberry green petal diseases have been linked to phytoplasma strains transmitted by known leafhopper species. However, the number of phytoplasma diseases has significantly increased in North America over the past decade, suggesting the presence of unidentified vectors or an abundance of leafhopper vectors. This short review provides an overview of the current knowledge on leafhoppers as vectors of phytoplasmas to berries, focusing on the last decade’s research in Canada. This paper also explores the potential implications of climate change on this pathosystem, including the anticipated range expansion of leafhopper species, changes in phytoplasma acquisition and transmission, and the risk of new leafhopper-transmitted plant-pathogen introductions through the arrival of new leafhopper species.

Mosquito (Diptera: Culicidae) populations in contrasting areas of the western regions of Burkina Faso: species diversity, abundance and their implications for pathogen transmission

BackgroundMosquitoes (Diptera: Culicidae) can have a significant negative impact on human health. The urbanization of natural environments and their conversion for agricultural use, as well as human population growth, may affect mosquito populations and increase the risk of emerging or re-emerging mosquito-borne diseases. We report on the variety and number of adult mosquitoes found in four environments with varying degrees of human impact (rural, urban, rice fields, and forest) located in a savannah zone of West Africa.MethodsMosquitoes were collected from two regions (Hauts-Bassins and Sud-Ouest) of Burkina Faso during five periods between August 2019 and June 2021. Sampling sites were grouped according to environment. Mosquitoes were collected using BG-Sentinel traps and double net traps, and Prokopack Aspirators. Statistical analyses were performed using R software version 4.1.2. Logistic regression, using generalised mixed linear models, was used to test the effect of environment on mosquito abundance and diversity. Alpha diversity analysis was also performed, using the vegan package.ResultsA total of 10,625 adult mosquitoes were collected, belonging to 33 species and five genera: Culex, Aedes, Anopheles, Mansonia, and Ficalbia. The most dominant species were Culex quinquefasciatus, Anopheles gambiae sensu lato and Aedes aegypti. Alpha diversity was similar in the two regions. Habitat had a significant effect on mosquito species richness, the Shannon index and the Simpson index. The rural environment had the highest species richness (n = 28) followed by the forest environment (n = 24). The highest number of mosquitoes (4977/10,625) was collected in the urban environment.ConclusionsThe species composition of the mosquito populations depended on the type of environment, with fewer species in environments with a high human impact such as urban areas and rice fields. Due to the diversity and abundance of the mosquito vectors, the human populations of all of the environments examined are considered to be at potential risk of mosquito-borne diseases.Graphical

Spatial–temporal vector abundance and malaria transmission dynamics in Nchelenge and Lake Mweru islands, a region with a high burden of malaria in northern Zambia

BackgroundOver a decade of vector control by indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) distribution on the mainland, and only LLINs on islands had a minimal impact on disease burden in Nchelenge district, northern Zambia. Anopheles funestus and Anopheles gambiae are vectors known only from the mainland. Understanding vector bionomics in the district is necessary for planning and targeting effective vector control. This study aimed to provide information on abundance, seasonality, and Plasmodium falciparum sporozoite infectivity of malaria vectors in Nchelenge, including islands.MethodsMosquitoes were collected in 192 CDC indoor light traps set in 56 households between January 2015 and January 2016. Morphological and molecular species identifications and P. falciparum circumsporoites by ELISA were performed. Mosquito counts and relative abundances from the islands and mainland were compared, and household factors associated with vector counts were determined.ResultsA total of 5888 anophelines were collected during the study. Of these, 5,704 were female Anopheles funestus sensu lato (s.l.) and 248 female An. gambiae s.l. The highest proportion of An. funestus (n = 4090) was from Chisenga Island and An. gambiae (n = 174) was from Kilwa Island. The highest estimated counts per trap for An. funestus s.l. were from Chisenga island, (89.9, p < 0.001) and from the dry season (78.6, p < 001). For An. gambiae the highest counts per trap were from Kilwa island (3.1, p < 0.001) and the rainy season (2.5, p = 0.007). The highest estimated annual entomological inoculation rate was from Chisenga Island with 91.62 ib/p/y followed by Kilwa Island with 29.77 ib/p/yr, and then Mainland with 19.97 ib/p/yr.ConclusionsThere was varied species abundance and malaria transmission risk across sites and seasons. The risk of malaria transmission was perennial and higher on the islands. The minimal impact of vector control efforts on the mainland was evident, but limited overall. Vector control intervention coverage with effective tools needs to be extended to the islands to effectively control malaria transmission in Nchelenge district.

Everglades virus: an underrecognized disease-causing subtype of Venezuelan equine encephalitis virus endemic to Florida, USA.

Everglades virus (EVEV) is subtype II of the Venezuelan equine encephalitis virus (VEEV) complex (Togaviridae: Alphavirus), endemic to Florida, USA. EVEV belongs to a clade that includes both enzootic and epizootic/epidemic VEEV subtypes. Like other enzootic VEEV subtypes, muroid rodents are important vertebrate hosts for EVEV and certain mosquitoes are important vectors. The hispid cotton rat Sigmodon hispidus and cotton mouse Peromyscus gossypinus are important EVEV hosts, based on natural infection (virus isolation and high seropositivity), host competence (experimental infections), and frequency of contact with the vector. The mosquito Culex (Melanoconion) cecedei is the only confirmed vector of EVEV based upon high natural infection rates, efficient vector competence, and frequent feeding upon muroid rodents. Human disease attributed to EVEV is considered rare. However, cases of meningitis and encephalitis are recorded from multiple sites, separated by 250 km or more. Phylogenetic analyses indicate that EVEV is evolving, possibly due to changes in the mammal community. Mutations in the EVEV genome are of concern, given that epidemic strains of VEEV (subtypes IAB and IC) are derived from enzootic subtype ID, the closest genetic relative of EVEV. Should epizootic mutations arise in EVEV, the abundance of Aedes taeniorhynchus and other epizootic VEEV vectors in southern Florida provides a conducive environment for widespread transmission. Other factors that will likely influence the distribution and frequency of EVEV transmission include the establishment of Culex panocossa in Florida, Everglades restoration, mammal community decline due to the Burmese python, land use alteration by humans, and climate change.

Distribution of Aedes mosquito species along the rural–urban gradient in Lambaréné and its surroundings

BackgroundAedes albopictus and Aedes aegypti are known for their potential as vectors of dengue (DENV) and chikungunya (CHIKV) viruses. However, entomological surveys are mostly carried out during epidemics. In Gabon where outbreaks of both viruses have occurred, there is no vector control program targeting these arboviruses. Therefore, we assessed the presence of Aedes species along a rural–urban gradient in Lambaréné (Gabon) and its surroundings and determined ecological factors associated to their presence.MethodsAn entomological survey was conducted in Lambaréné and its surrounding rural areas. Mosquitoes were collected with aspirators around human dwellings, and ecological and environmental data were collected from each study area. Morphological identification keys were used to identify Aedes species. RNA was extracted from pools of female mosquitoes and amplified by RT-qPCR to detect the presence of DENV and CHIKV.ResultsOverall, the most common vector collected was Aedes albopictus (97%, 4236/4367 specimens), followed by Aedes aegypti (3%, 131/4367). Albopictus vectors was more abundant in the rural area (Wilcoxon signed-rank test, Z = 627, P = 0.043) than in the urban area. In the urban area, a higher number of mosquitoes (45%) were recorded in the economic zone (zone 3) than in the historical and administrative zones (zone 1 and 2). In the rural area, the proportions of species numbers were significantly higher along the south rural transect (92%) compared to the north rural transect (Wilcoxon signed-rank test, Z = 43, P ˂ 0.016). We also noted a high abundance of vectors in environments characterized by monocultures of Hevea brasiliensis (Hevea) and Manihot esculenta (cassava) (Kruskal–Wallis H-test, H = 25.7, df = 2, P < 0.001). Finally, no mosquito pools were positive for either DENV or CHIKV.ConclusionAedes albopictus was the dominant vector across the study sites due to its high invasiveness capacity. This presence re-affirms the potential for local transmission of both DENV and CHIKV, as indicated previously by serological surveys conducted in our study area, even though no transmission was detected during the current study. These findings underscore the need for regular arbovirus surveillance in the study region, with the aim of supporting vector control efforts in the event of outbreaks.Graphical

Determination of sporozoite infection rate of indoor resting female Anopheles mosquitoes in Gombe South, Gombe State, Nigeria

Infected female Anopheles mosquitoes are the culprits of malaria. The abundance and distribution of malaria vectors in communities contribute significantly in malaria transmission. Understanding the magnitude and intensity of sporozoite infection rates is very sensitive and powerful indices for describing the epidemiology of malaria which will aid in strategizing malaria control programme. The present study determines the sporozoite infection rates of female Anopheles mosquitoes in the four Local Government Areas (LGA) of Gombe South, Gombe State, Northeastern Nigeria. Mosquitoes were collected using Pyrethrum Spray Catch (PSC) and were dissected to check the presence of sporozoites. Out of the 1,860 female Anopheles mosquitoes dissected, 665(35.8%) were infected with sporozoites. The highest infection rate was observed from Kaltungo LGA 145(41.7%), followed by Billiri LGA 182(36.3%), and 205(35.4%) was recorded from Balanaga. The lowest infectivity rate was observed from Shongom LGA 133(30.9%), p&lt;0.005 which is highly significant statistically. With regards to monthly distribution of sporozoites, the highest infection rate was recorded in December (64.7%), January 60.0%, (64.5%), and August (60.7%) from Balanga, Billiri, Kaltungo and Shongom LGA respectively. Meanwhile the least was observed in July (2.8%), December (7.7%), April (20.0%), and March (11.6%) from Balanga, Billiri, Kaltungo and Shongom LGA respectively, p&lt;0.005 which is highly significant statistically. However, (0.0%) sporozoite infection was obtained in September and March from Billiri, Kaltungo and Shongom LGA respectively. The present study therefore recommends malaria vector control through community based efforts by destruction of mosquitoes breeding sites, use of insect’s repellents, environmental sanitation and application of oil in stagnant water in order to reduce vectors population.

Spatial analyses of Plasmodium knowlesi vectors with reference to control interventions in Malaysia

BackgroundMalaria parasites such as Plasmodium knowlesi, P. inui, and P. cynomolgi are spread from macaques to humans through the Leucosphyrus Group of Anopheles mosquitoes. It is crucial to know the distribution of these vectors to implement effective control measures for malaria elimination. Plasmodium knowlesi is the most predominant zoonotic malaria parasite infecting humans in Malaysia.MethodsVector data from various sources were used to create distribution maps from 1957 to 2021. A predictive statistical model utilizing logistic regression was developed using significant environmental factors. Interpolation maps were created using the inverse distance weighted (IDW) method and overlaid with the corresponding environmental variables.ResultsBased on the IDW analysis, high vector abundances were found in the southwestern part of Sarawak, the northern region of Pahang and the northwestern part of Sabah. However, most parts of Johor, Sabah, Perlis, Penang, Kelantan and Terengganu had low vector abundance. The accuracy test indicated that the model predicted sampling and non-sampling areas with 75.3% overall accuracy. The selected environmental variables were entered into the regression model based on their significant values. In addition to the presence of water bodies, elevation, temperature, forest loss and forest cover were included in the final model since these were significantly correlated. Anopheles mosquitoes were mainly distributed in Peninsular Malaysia (Titiwangsa range, central and northern parts), Sabah (Kudat, West Coast, Interior and Tawau division) and Sarawak (Kapit, Miri, and Limbang). The predicted Anopheles mosquito density was lower in the southern part of Peninsular Malaysia, the Sandakan Division of Sabah and the western region of Sarawak.ConclusionThe study offers insight into the distribution of the Leucosphyrus Group of Anopheles mosquitoes in Malaysia. Additionally, the accompanying predictive vector map correlates well with cases of P. knowlesi malaria. This research is crucial in informing and supporting future efforts by healthcare professionals to develop effective malaria control interventions.Graphical

Spatiotemporal organization of cryptic North American Culex species along an urbanization gradient.

Landscape heterogeneity creates diverse habitat and resources for mosquito vectors of disease. A consequence may be varied distribution and abundance of vector species over space and time dependent on niche requirements.We tested the hypothesis that landscape heterogeneity driven by urbanization influences the distribution and relative abundance of Culex pipiens, Cx. restuans, and Cx. quinquefasciatus, three vectors of West Nile virus (WNv) in the eastern North American landscape. We collected 9,803 cryptic Culex from urban, suburban, and rural sites in metropolitan Washington, District of Columbia, during the months of June-October, 2019-2021. In 2021, we also collected mosquitoes in April and May to measure early-season abundance and distribution. Molecular techniques were used to identify a subset of collected Culex to species (n = 2,461). Ecological correlates of the spatiotemporal distribution of these cryptic Culex were examined using constrained and unconstrained ordination.Seasonality was not associated with Culex community composition in June-October over three years but introducing April and May data revealed seasonal shifts in community composition in the final year of our study. Culex pipiens were dominant across site types, while Cx. quinquefasciatus were associated with urban environments, and Cx. restuans were associated with rural and suburban sites. All three species rarely coexisted.Our work demonstrates that human-mediated land-use changes influence the distribution and relative abundance of Culex vectors of WNv, even on fine geospatial scales. Site classification, percent impervious surface, distance to city center, and longitude predicted Culex community composition. We documented active Culex months before vector surveillance typically commences in this region, with Culex restuans being most abundant during April and May. Active suppression of Cx. restuans in April and May could reduce early enzootic transmission, delay the seasonal spread of WNv, and thereby reduce overall WNv burden. By June, the highest risk of epizootic spillover of WNv to human hosts may be in suburban areas with high human population density and mixed Culex assemblages that can transmit WNv between birds and humans. Focusing management efforts there may further reduce human disease burden.

Cultural control methods improve management of leafhopper vector of X-disease

X-disease, caused by the phytoplasma ‘Candidatus Phytoplasma pruni’, is currently threatening Pacific Northwest (USA) stone fruit (Prunus) production, particularly sweet cherry (P. avium). There is no cure, and infected fruit remain unmarketable throughout the tree's life. Management efforts focus on reducing transmission through infected tree removal and frequent chemical applications to control the leafhopper vectors. The increase in chemical inputs has broken down stone fruit integrated pest management techniques and is neither economically nor environmentally sustainable. To investigate sustainable vector management, we assessed the efficacy of two long-lasting cultural management techniques, kaolin clay (Surround WP) and reflective plastic geotextile (Extenday), to deter leafhoppers from trees and prevent population growth within orchards. These methods were tested against untreated control plots in Washington State commercial stone fruit blocks in 2021 and 2022. Colladonus montanus reductus (Van Duzee) was the most abundant leafhopper vector species captured in both years. In cherry blocks, Extenday consistently reduced C. m. reductus densities by 80–90%, while kaolin clay caused a 45–50% reduction in leafhoppers, but only when they were abundant (more than 10 leafhoppers per trap). Sticky cards placed at varying heights revealed that kaolin clay caused C. m. reductus to be proportionally more abundant near the ground cover than in the tree canopy regardless of overall population density. The combination of reducing C. m. reductus density and shifting their distribution into the ground cover demonstrates both plastic geotextiles and kaolin clay provide effective post-harvest strategies for X-disease vector management.

Diversity and larval habitats of mosquitoes (Diptera: Culicidae) in urban areas in Ha Noi, Vietnam

Although some mosquito-borne diseases have been thriving in Ha Noi city, Vietnam very few studies on mosquitoes have been conducted. Determining how the species composition and abundance of mosquito vectors depend on environmental resources in different habitats addresses where different types of vector control need to be applied. The present study aims to investigate the characteristics of larval habitats and to provide a composition of mosquitoes (Culicidae) in this city. Surveys of larval and adult mosquitoes were carried out from different habitats in urban areas during rainy seasons from 2018 to 2023. Overall, in almost all water containers that were surveyed (80.9%), immature mosquitoes were present. A total of 4593 mosquitoes including 3,950 larvae and 643 adults were collected from 16 sampling sites. Twelve mosquito species belonging to 6 genera were collected and identified. Aedes albopictus and Culex quinquefasciatus were the most common and abundant species, each accounting for 34% of the total collected larval specimens. Five species, Anopheles umbrosus, Culex cintellus, Armigeres subalbatus, Mansonia annulifera, and Lutzia fuscana were the first records for Ha Noi city. The species composition varied between different habitat types. Peri-domestic habitats were the most common breeding sites for mosquitoes in the study area. Noteworthy, species belonging to genus Aedes were abundant in domestic habitats created by anthropogenic materials while that of genus Culex was mainly thriving in large water bodies in both peri-domestic and natural habitats. The current results show a variation in the distribution and abundance of mosquitoes in urban areas of Ha Noi which should be considered for effective planning and implementing mosquito control programs in the city.