Avian Plasmodium infection in field‐collected mosquitoes during 2012–2013 in Tarlac,Philippines

Global warming threatens to increase the spread and prevalence of mosquito‐transmitted diseases. Certain pathogens may be carried by migratory birds and transmitted to local mosquito populations. Mosquitoes were collected in the northern Philippines during bird migration seasons to detect avian malaria parasites as well as for the identification of potential vector species and the estimation of infections among local mosquito populations. We used the nested PCR to detect the avian malaria species. Culex vishnui (47.6%) was the most abundant species collected and Cx. tritaeniorhynchus (13.8%) was the second most abundant. Avian Plasmodium parasites were found in eight mosquito species, for which the infection rates were between 0.5% and 6.2%. The six Plasmodium genetic lineages found in this study included P. juxtanucleare ‐GALLUS02, Tacy7 (Donana04), CXBIT01, Plasmodium species LIN2 New Zealand, and two unclassified lineages. The potential mosquito vectors for avian Plasmodium parasites in the Philippines were Cq. crassipes, Cx. fuscocephala, Cx. quinquefasciatus, Cx. sitiens, Cx. vishnui, and Ma. Uniformis; two major genetic lineages, P. juxtanucleare and Tacy7, were identified.     

Dynamics and diversity of mosquito vectors of Japanese encephalitis virus in Kandal province,Cambodia

The Japanese encephalitis virus (JEV) is one of the main causes of encephalitis in Asia, including Cambodia. An understanding of the interactions between JEV hosts and vectors (Diptera: Culicidae) remains rare in the context of expanding urbanization. The relative abundance, species diversity and population dynamics of potential JEV vectors were studied between August 2015 and July 2016 on a peri-urban and rural pig farm in Kandal province, Cambodia, where JEV is circulating. Five similar environments in the two farms were selected for mosquito trapping: pig farm, cattle house, river/canals, household/ponds and paddy fields. The main objective was to describe the distribution and the dynamics of the main JEV vector mosquito species. In total, 83,013 mosquitoes from 20 species were caught in rural and peri-urban areas, and 82.3% of the mosquitoes were potential JEV vector species. In peri-urban areas, Culex (Cx.) gelidus was the most abundant species, followed by Cx. vishnui subgroup and Cx. tritaeniorhynchus. In rural areas, the same species were dominant: Cx. vishnui subgroup, Cx. gelidus and Cx. tritaeniorhynchus. The vast majority of mosquitoes (95.9%) were collected in close proximity to pigs and cattle. In conclusion, JEV vectors were present at all study sites and throughout all months of the year, supporting a continuous circulation of JEV in Cambodia.     

Diversity,distribution, abundance,and feeding pattern of tropical ornithophilic mosquitoes

Bird–biting mosquitoes act as bridge vectors of diverse pathogens of emerging infectious diseases. In this study, we report for the first time the abundance, diversity, distribution, and feeding pattern of bird‐biting mosquitoes on an island where avifaunal diversity is rich. Monthly mosquito collections were done at six different habitats in three different climatic zones using bird‐baited traps over a year. Collected mosquitoes were identified using morphological and molecular tools. A total of 2,655 bird‐biting mosquitoes of eight genera and 25 species were identified. Of these, 52% were Culex species, which represents 35% of the Culex species in the country. The most abundant species were Culex sitiens, Cx. pseudovishnui, Cx. nigropunctatus and Cx. quinquefasciatus, whereas the latter two were common to all habitats. The highest abundance was reported in lowland forests (49.6%), while it was lowest in highland forests (22.3%). Highest species similarity was reported from highland forests. Seasonal variations of the most abundant species were significantly different in selected habitats (p< 0.05). Two distinct biting peaks were identified, from 06:00 to 21:00 and 22:00 to 02:00. The biting nature of identified ornithophilic mosquitoes suggests the potential vector status of these mosquitoes.     

Molecular Epidemiology of Japanese Encephalitis Virus in Mosquitoes in Taiwan during 2005–2012

Japanese encephalitis (JE) is a mosquito-borne zoonotic disease caused by the Japanese encephalitis virus (JEV). Pigs and water birds are the main amplifying and maintenance hosts of the virus. In this study, we conducted a JEV survey in mosquitoes captured in pig farms and water bird wetland habitats in Taiwan during 2005 to 2012. A total of 102,633 mosquitoes were collected. Culex tritaeniorhynchus was the most common mosquito species found in the pig farms and wetlands. Among the 26 mosquito species collected, 11 tested positive for JEV by RT-PCR, including Cx. tritaeniorhynchus, Cx. annulus, Anopheles sinensis, Armigeres subalbatus, and Cx. fuscocephala. Among those testing positive, Cx. tritaeniorhynchus was the predominant vector species for the transmission of JEV genotypes I and III in Taiwan. The JEV infection rate was significantly higher in the mosquitoes from the pig farms than those from the wetlands. A phylogenetic analysis of the JEV envelope gene sequences isolated from the captured mosquitoes demonstrated that the predominant JEV genotype has shifted from genotype III to genotype I (GI), providing evidence for transmission cycle maintenance and multiple introductions of the GI strains in Taiwan during 2008 to 2012. This study demonstrates the intense JEV transmission activity in Taiwan, highlights the importance of JE vaccination for controlling the epidemic, and provides valuable information for the assessment of the vaccine''s efficacy.     

Irrigation scheme or mosquito hazard: a case study in Mwea Irrigation Scheme

A survey of the mosquito fauna in the Mwea-Tebere Irrigation Scheme in Kenya was conducted between 1984 and 1985. Two genera, Anopheles and Culex were found indoors in large numbers. The major species were Anopheles gambiae s.l., Anopheles pharoensis, and Culex quinquefasciatus, comprising 66% and 21% of the total catch, respectively. The large numbers of mosquitoes found resting indoors showed seasonal population fluctuations. The seasonal population increases observed were due to the availability of larval breeding conditions over a long period of time and to man-made environmental changes. These changes included irrigation canals and rice paddies. The irrigation canals and rice paddies were flooded from August till December, thus linking the flooding effects of the two rainy seasons. This enabled mosquitoes to breed continuously for up to 9 months per year.     

Population dynamics of mosquitoes (Diptera: Culicidae) and their disease-harboring rates in Gyeonggi province,South Korea

Population dynamics and species composition of mosquitoes were monitored in a suburban residential area and rural areas, including a migratory bird refuge area and a cattle farm area, from 2017 to 2019. Mosquitoes were collected every two weeks using one BG sentinel trap and two black-light traps in a suburban residential area and a migratory bird refuge area, and one black-light trap in a cattle farm area from March to November. From the surveillance, a total of 13,267, 9,697 and 6,688 mosquitoes were collected in 2017, 2018, and 2019, respectively. The peak of the mosquito population was observed in August and September in both the suburban residential area and rural areas. In general, Culex pipiens pallens was the dominant species in the suburban residential area, whereas Aedes vexans nipponii and Anopheles spp. were the most dominant in the rural areas. Collected mosquitoes were pooled into groups for each collection site and species to investigate flavivirus harboring. Three pools were positive for Japanese encephalitis virus type V, one pool was positive for Chaoyang virus, and six pools were positive for Culex flavi virus from the 731 pools tested. When total numbers of collected mosquitoes were further analyzed by linear regression analysis for their interaction with ambient temperature and relative humidity, the number of mosquitoes were significantly affected by the ambient temperature. In contrast, relative humidity was significantly affecting the total number of mosquitoes only for the migratory bird refuge area.     

Using Bloodmeal Analysis to Assess Disease Risk to Wildlife at the New Northern Limit of a Mosquito Species

The historically southeastern mosquito species Culex erraticus has over the last 30 years undergone a marked expansion north. We evaluated this species’ potential to participate in local disease cycles in the northeastern USA by identifying the vertebrate sources of blood in Cx. erraticus specimens from New Jersey. We found that the majority of bloodmeals (92.6%) were derived from birds, followed by 6.8% from mammals (of which half were human), and a single amphibian bloodmeal from a spring peeper (0.56%). Medium- and large-sized water birds from the order Pelecaniformes made up 60.4% of the bird species and 55.9% of all identified hosts. This group of birds is known enzootic hosts of arboviruses such as eastern equine encephalitis virus, for which Cx. erraticus is a competent vector. Additionally, we screened blooded mosquitoes for avian malaria parasites and identified three different lineages of Plasmodium, including what may represent a new Plasmodium species (likely a wetland bird specialist) in bloodmeals from Green Herons, a Great Egret, and a Double-Crested Cormorant. Our results support the utility of mosquito bloodmeals as sources of information about circulating wildlife pathogens and reveal the potential of range-expanding species to intensify local zoonoses and bridge enzootic pathogens to humans.     

Ticks collected from migratory birds,including a new record of Haemaphysalis formosensis,on Jeju Island,Korea

Migratory birds may disperse parasites across ecological barriers, and recent climate change may alter the pattern of ectoparasite dispersal via changed patterns of bird migration. In order to document the parasitization of migratory birds by Ixodidae ticks on Jeju Island in Korea, we examined 934 migratory birds comprising 75 species for ticks from 2010 to 2012. In total, 313 ticks were collected from 74 migratory birds across 17 avian species and identified based on morphological keys. These ticks represented six species: Haemaphysalis flava, H. formosensis, H. longicornis, H. concinna, Ixodes turdus and I. nipponensis. Of particular note was the presence of H. formosensis, a species not previously reported to have been found in Korea, and H. concinna, which had not been previously reported on Jeju Island. The dominant tick species found were H. flava (226 ticks, 72.2 %) and I. turdus (54 ticks, 17.3 %), and ground-dwelling thrushes such as Pale thrushes (Turdus pallidus; 39 birds, 52.7 %) were the most important hosts. Although H. longicornis is the most abundant and prevalent terrestrial tick on Jeju Island, the species accounted for only 3.8 % of the total ticks collected in this study, suggesting that ticks on migratory birds may differ from the local tick fauna and that exotic ticks may be introduced via migratory birds. Therefore, long-term programs for tick and tick-borne disease surveillance are recommended to understand the role of migratory animals in the introduction of exotic species and associated pathogens and in life cycles of ticks at different stages in this region.     

The mosquitoes (Diptera: Culicidae) of Tabasco,Mexico

To document and update the mosquito species of Tabasco, Mexico, field collection trips were conducted in the two physiographic regions of Tabasco: the coastal plain of the southern gulf and the mountains of Chiapas and Guatemala. Mosquitoes were collected as immature and adult stages during the dry and rainy seasons from 2014 through 2015. Additionally, the Reference Collection of Arthropods of Medical Importance (CAIM‐InDRE) containing mosquitoes of Tabasco was re‐examined. In total, 4,913 specimens were collected and examined, which are divided into seven tribes, 18 genera, 27 subgenera, and 104 species. Of these, one genus (Shannoniana Lane and Cerqueira), two subgenera (Georgecraigius Reinert, Harbach and Kitching, and Carrollia Lutz), and 21 species are new records for the mosquito fauna of Tabasco. Culex metempsytus Dyar is a new record for Mexico and Wyeomyia jocosa (Dyar and Knab) is removed from the Mexican mosquito fauna. Seventeen species historically reported were not found in the field collections conducted here. Taxonomic notes, new distribution limits, and comments about the medical importance of species of mosquitoes of Tabasco are discussed. Tabasco is the second state in Mexico with the largest mosquito richness (104 species), followed by Veracruz with 139 species.     

Avian Plasmodium in Culex and Ochlerotatus Mosquitoes from Southern Spain: Effects of Season and Host-Feeding Source on Parasite Dynamics

Haemosporidians, a group of vector-borne parasites that include Plasmodium, infect vertebrates including birds. Although mosquitoes are crucial elements in the transmission of avian malaria parasites, little is known of their ecology as vectors. We examined the presence of Plasmodium and Haemoproteus lineages in five mosquito species belonging to the genera Culex and Ochlerotatus to test for the effect of vector species, season and host-feeding source on the transmission dynamics of these pathogens. We analyzed 166 blood-fed individually and 5,579 unfed mosquitoes (grouped in 197 pools) from a locality in southern Spain. In all, 15 Plasmodium and two Haemoproteus lineages were identified on the basis of a fragment of 478 bp of the mitochondrial cytochrome b gene. Infection prevalence of blood parasites in unfed mosquitoes varied between species (range: 0–3.2%) and seasons. The feeding source was identified in 91 mosquitoes where 78% were identified as bird. We found that i) several Plasmodium lineages are shared among different Culex species and one Plasmodium lineage is shared between Culex and Ochlerotatus genera; ii) mosquitoes harboured Haemoproteus parasites; iii) pools of unfed females of mostly ornithophilic Culex species had a higher Plasmodium prevalence than the only mammophylic Culex species studied. However, the mammophylic Ochlerotatus caspius had in pool samples the greatest Plasmodium prevalence. This relative high prevalence may be determined by inter-specific differences in vector survival, susceptibility to infection but also the possibility that this species feeds on birds more frequently than previously thought. Finally, iv) infection rate of mosquitoes varies between seasons and reaches its maximum prevalence during autumn and minimum prevalence in spring.     

Black light trap collections in Wangging county and Yanji city,Jilin Province,China, August 2006–2007

Adult mosquito surveillance was conducted using black light traps in August of 2006 and 2007 at Wangging county and Yanji city, Jilin Province, China to identify the distribution of anopheline mosquitoes in northern China. A total of 2459 female mosquitoes comprising three genera and eight species including Anopheles (Anopheles) lesteri, An. (Ano.) kleini, An. (Ano.) pullus, Culex inatomii, Cx. orientalis, Cx. pipiens, Cx. bitaeniorhynchus and Aedes vexans nipponii were collected. The most commonly collected species was An. kleini which had not been previously reported from China. Anopheles sinensis sensu stricto is commonly collected throughout China, but was not collected from these areas.     

The influence of mistletoes on birds in an agricultural landscape of central Mexico

Mistletoes are hemiparasitic flowering plants that function as keystone resources in forests and woodlands of temperate regions, where a positive relationship between mistletoe density and avian species richness has been observed. Mistletoes have been less studied in tropical regions and the relationship between birds and mistletoes has seldom been explored in tropical agricultural systems. Therefore, we studied the presence of infected trees and infection prevalence (i.e., number of parasitized trees/total number of trees) by Psittacanthus (Loranthaceae) mistletoes in 23 hedgerows located in an agricultural landscape of central Mexico during the dry and rainy seasons, and investigated the relationship between bird species richness and abundance and the abundance of mistletoes. We found a mean of 74 mistletoe plants per 100-m transect of only one species, Psittacanthus calyculatus. Thirty-one percent of the trees surveyed were infected and tree species differed in infection prevalence, mesquite (Prosopis laevigata) being the most infected species with 86% of the surveyed trees infected. For both seasons, we found a positive and significant association between bird species richness and number of mistletoe plants. The same pattern was observed for total bird abundance. Many resident and Neotropical migratory birds were observed foraging on mistletoes. Our results show that mistletoes are important in promoting a higher bird species richness and abundance in tropical agricultural landscapes.     

Insecticide resistance status of three vectors of Japanese encephalitis in east central India

Japanese encephalitis (JE) has been reported in different districts of Odisha state (east central India) since 1992. During 2016, a major outbreak of JE and acute encephalitis syndrome (AES) occurred in the Malkangiri district of Odisha, causing 103 deaths in children, of which 37 were caused by JE and 66 by AES. Information on insecticide resistance in JE vectors is important for the selection of appropriate insecticides for use in vector control. The present study was designed to determine the resistance status of three important vectors of JE, Culex vishnui, Culex tritaeniorhynchus and Culex bitaeniorhynchus (Diptera: Culicidae), against dichlorodiphenyltrichloroethane (DDT), malathion and deltamethrin in three districts of Odisha state affected by JE. Female adult mosquitoes were collected using mouth aspirators both indoors and outdoors in JE‐affected villages and used in susceptibility bioassays following World Health Organization guidelines. Knock‐downs were recorded every 10 min up to 1 h and mortality rates were recorded at 24 h post‐exposure. Culex vishnui and Cx. tritaeniorhynchus showed resistance to DDT, malathion and deltamethrin, whereas Cx. bitaeniorhynchus was susceptible in all study districts. The information generated by this study will be highly useful in the planning and implementing of appropriate vector control operations for the prevention and control of JE in east central India.     

An Integrative Eco-Epidemiological Analysis of West Nile Virus Transmission

West Nile disease, caused by the West Nile virus (WNV), is a mosquito-borne zoonotic disease affecting humans and horses that involves wild birds as amplifying hosts. The mechanisms of WNV transmission remain unclear in Europe where the occurrence of outbreaks has dramatically increased in recent years. We used a dataset on the competence, distribution, abundance, diversity and dispersal of wild bird hosts and mosquito vectors to test alternative hypotheses concerning the transmission of WNV in Southern France. We modelled the successive processes of introduction, amplification, dispersal and spillover of WNV to incidental hosts based on host–vector contact rates on various land cover types and over four seasons. We evaluated the relative importance of the mechanisms tested using two independent serological datasets of WNV antibodies collected in wild birds and horses. We found that the same transmission processes (seasonal virus introduction by migratory birds, Culex modestus mosquitoes as amplifying vectors, heterogeneity in avian host competence, absence of ‘dilution effect’) best explain the spatial variations in WNV seroprevalence in the two serological datasets. Our results provide new insights on the pathways of WNV introduction, amplification and spillover and the contribution of bird and mosquito species to WNV transmission in Southern France.     

Birds as hosts of ixodid ticks (Acarina,Ixodidae)

rophic relations between ixodid ticks of the world fauna parasitizing as adults on birds are analyzed. These ticks include 60 out of 650 species of the family Ixodidae and belong to the genera Ixodes, Haemaphysalis, and Amblyomma. Relations between birds and ticks of the genus Ixodes are most ancient. Colonial marine birds seem to be the first hosts of ixodid ticks in the class of birds. Trophic specialization of ticks is not associated with bird taxa, because in most cases no tick specificity is caused by either phylogenetic features of hosts, or specific environmental conditions.     

Preliminary report of knockdown resistance in Culex pipiens pallens and Aedes koreicus from Korea

Pyrethroid insecticides have been effective and powerful for controlling mosquitoes. However, abuse of these insecticides increases the number of resistant mosquitoes. In this study, Culex pipiens pallens and Aedes koreicus were collected from an artificial reservoir in the vicinity of a populated area in Korea, which is also a migratory bird catchment area. To monitor resistance to pyrethroid insecticides in mosquitoes, genomic DNA from the collected mosquitoes was sequenced for the kdr mutation in the voltage‐gated sodium channel (VGSC) gene. As a result, three samples with homozygous resistance (17.6%) and one with heterozygous resistance (5.9%) were found among 17 Cx. pipiens pallens specimens. One of the samples had a unique sequence at the amplified VGSC region. Of the 15 Ae. koreicus, no insecticide resistant individuals were found. In Korea, this is the first report of kdr genetic traits in Ae. koreicus and Cx. pipiens pallens and of a unique VGSC allele in Cx. pipiens pallens. Further investigation is needed to monitor the kdr resistance of these species in Korea and to determine how the unique sequence found in Cx. pipiens pallens is related to insecticide resistance.     

Seasonal abundance and habitat use of bird species in and around Wondo Genet Forest,south‐central Ethiopia

The habitat use and seasonal migratory pattern of birds in Ethiopia is less explored as compared to diversity studies. To this end, this study aimed at investigating the patterns of distribution related to seasonality and the effect of habitat characteristics (elevation, slope, and average vegetation height) on habitat use of birds of Wondo Genet Forest Patch. A stratified random sampling design was used to assess the avian fauna across the four dominant habitat types found in the study area: natural forest, wooded grassland, grassland, and agroforestry land. A point transect count was employed to investigate avian species richness and abundance per habitat type per season. Ancillary data, such as elevation above sea level, latitude and longitude, average vegetation height, and percent slope inclination, were recorded with a GPS and clinometers per plot. A total of 33 migratory bird species were recorded from the area, of which 20 species were northern (Palearctic) migrants while 13 were inter‐African migrants. There was a significant difference in the mean abundance of migratory bird species between dry and wet seasons (t = 2.13, p = .038, df = 44). The variation in mean abundance per plot between the dry and wet seasons in the grassland habitat was significant (t = 2.35, p = .051, df = 7). In most habitat types during both dry and wet seasons, omnivore birds were the most abundant. While slope was a good predictor for bird species abundance in the dry season, altitude and average vegetation height accounted more in the wet season. The patch of forest and its surrounding is an important bird area for migratory, endemic, and global threatened species. Hence, it is conservation priority area, and the study suggests that conservation coupled with ecotourism development is needed for its sustainability.     

Seasonal Incidence and Diversity Pattern of Avian Communities in the Bangalore University Campus,India

The present study deals with the species abundance, diversity and species richness of avian communities in the Bangalore University Campus (BUC), Bengaluru, India. One hundred and six species of birds belonging to 42 families under 68 genera were recorded. Shannon–Wiener’s and Fisher’s alpha diversities, species evenness, species richness of bird communities, number of bird species and percentage of population density of birds between various seasons in the BUC differed significantly between the study years. Of these bird species, the relative abundance (6.96 %) and species distribution ratio (0.070) of Psittacula krameri were highest, whereas relative abundance (0.04 %) and species distribution ratio (0.002) of Coracias benghalensis were lowest. The existing 32 species of flowering plants/trees belonging to 29 genera under 14 families in the campus are used for perching by birds. Moreover 29 species of flowering plants/trees belonging to 24 genera under 16 families depend on birds for pollination and/or seed dispersal. Occurrence of greater bird diversity and abundance of avian communities were recorded highest in the winter season in the BUC premises. In the different seasons, the BUC had varying community structure of birds between the study years. BUC suffers from numerous threats namely grass cutting, fire and grazing of domestic animals. Conservation methods needed for habitat management are restoration of vegetation and wetlands, and increase plant and tree diversity to protect the ecosystem of BUC habitat and to preserve its diversity of avifauna.     

Mosquito vectors of the 1998-1999 outbreak of Rift Valley Fever and other arboviruses (Bagaza, Sanar, Wesselsbron and West Nile) in Mauritania and Senegal

Following an outbreak of Rift Valley fever (RVF) in south-eastern Mauritania during 1998, entomological investigations were conducted for 2 years in the affected parts of Senegal and Mauritania, spanning the Sénégal River basin. A total of 92 787 mosquitoes (Diptera: Culicidae), belonging to 10 genera and 41 species, were captured in light traps. In Senegal, Culex poicilipes (41%) and Mansonia uniformis (39%) were the most abundant species caught, whereas Aedes vexans (77%) and Cx. poicilipes (15%) predominated in Mauritania. RVF virus was isolated from 63 pools of Cx. poicilipes: 36 from Senegal in 1998 and 27 from Mauritania in 1999. These results are the first field evidence of Cx. poicilipes naturally infected with RVFV, and the first isolations of this virus from mosquitoes in Mauritania - the main West African epidemic and epizootic area. Additional arbovirus isolates comprised 25 strains of Bagaza (BAG) from Aedes fowleri, Culex neavei and Cx. poicilipes; 67 Sanar (ArD 66707) from Cx. poicilipes; 51 Wesselsbron (WSL) from Ae. vexans and 30 strains of West Nile (WN) from Ma. uniformis, showing differential specific virus-vector associations in the circulation activity of these five arboviruses.     

The distribution of mosquitoes (Diptera,Culicidae) in the Republic of Azerbaijan

The mosquito fauna in the territory of the Republic of Azerbaijan comprises 24 species from 7 genera. The dominant species are Anopheles sacharovi, Culex pipiens, Aedes caspius, and Ae. geniculatus in the forest area, and Coquillettidia richiardii in the lowlands, where there are swamps overgrown with reeds.