Seasonal dynamics in mosquito abundance and temperature do not influence avian malaria prevalence in the Himalayan foothills

We examined seasonal prevalence in avian haemosporidians (Plasmodium and Haemoproteus) in migrant and resident birds in western Himalaya, India. We investigated how infection with haemosporidians in avian hosts is associated with temporal changes in temperature and mosquito abundance along with host abundance and life‐history traits (body mass). Using molecular methods for parasite detection and sequencing partial cytochrome b gene, 12 Plasmodium and 27 Haemoproteus lineages were isolated. Our 1‐year study from December 2008 to December 2009 in tropical Himalayan foothills revealed a lack of seasonal variation in Plasmodium spp. prevalence in birds despite a strong correlation between mosquito abundance and temperature. The probability of infection with Plasmodium decreased with increase in temperature. Total parasite prevalence and specifically Plasmodium prevalence showed an increase with average avian body mass. In addition, total prevalence exhibited a U‐shaped relationship with avian host abundance. There was no difference in prevalence of Plasmodium spp. or Haemoproteus spp. across altitudes; parasite prevalence in high‐altitude locations was mainly driven by the seasonal migrants. One Haemoproteus lineage showed cross‐species infections between migrant and resident birds. This is the first molecular study in the tropical Himalayan bird community that emphasizes the importance of studying seasonal variation in parasite prevalence. Our study provides a basis for further evolutionary study on the epidemiology of avian malaria and spread of disease across Himalayan bird communities, which may not have been exposed to vectors and parasites throughout the year, with consequential implications to the risk of infection to naïve resident birds in high altitude.     

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.     

Avian Plasmodium lineages found in spot surveys of mosquitoes from 2007 to 2010 at Sakata wetland,Japan: do dominant lineages persist for multiple years?

The ecology and geographical distribution of disease vectors are major determinants of spatial and temporal variations in the transmission dynamics of vector‐borne pathogens. However, there are limited studies on the ecology of vectors that contribute to the natural transmission of most vector‐borne pathogens. Avian Plasmodium parasites are multihost mosquito‐borne pathogens transmitted by multiple mosquito species, which might regulate the diversity and persistence of these parasites. From 2007 to 2010, we conducted entomological surveys at Sakata wetland in central Japan, to investigate temporal variation in mosquito occurrence and prevalence of avian Plasmodium lineages in the mosquito populations. A polymerase chain reaction (PCR)‐based method was used to detect Plasmodium parasites and identify the blood sources of mosquitoes. Culex inatomii and C. pipiens pallens represented 60.0% and 34.8% of 11 mosquito species collected, respectively. Our results showed that the two dominant mosquito species most likely serve as principal vectors of avian Plasmodium parasites during June, which coincides with the breeding season of bird species nesting in the wetland reed beds. Fourteen animal species were identified as blood sources of mosquitoes, with the oriental reed warbler (Acrocephalus orientalis) being the commonest blood source. Although there was significant temporal variation in the occurrence of mosquitoes and prevalence of Plasmodium lineages in the mosquitoes, the dominant Plasmodium lineages shared by the two dominant mosquito species were consistently found at the same time during transmission seasons. Because vector competence cannot be confirmed solely by PCR approaches, experimental demonstration is required to provide definitive evidence of transmission suggested in this study.     

Evidence of Culiseta mosquitoes as vectors for Plasmodium parasites in Alaska

Mosquito vectors play a crucial role in the distribution of avian Plasmodium parasites worldwide. At northern latitudes, where climate warming is most pronounced, there are questions about possible changes in the abundance and distribution of Plasmodium parasites, their vectors, and their impacts to avian hosts. To better understand the transmission of Plasmodium among local birds and to gather baseline data on potential vectors, we sampled a total of 3,909 mosquitoes from three locations in south‐central Alaska during the summer of 2016. We screened mosquitoes for the presence of Plasmodium parasites using molecular techniques and estimated Plasmodium infection rates per 1,000 mosquitoes using maximum likelihood methods. We found low estimated infection rates across all mosquitoes (1.28 per 1,000), with significantly higher rates in Culiseta mosquitoes (7.91 per 1,000) than in Aedes mosquitoes (0.57 per 1,000). We detected Plasmodium in a single head/thorax sample of Culiseta, indicating potential for transmission of these parasites by mosquitoes of this genus. Plasmodium parasite DNA isolated from mosquitoes showed a 100% identity match to the BT7 Plasmodium lineage that has been detected in numerous avian species worldwide. Additionally, microscopic analysis of blood smears collected from black‐capped chickadees (Poecile atricapillus) at the same locations revealed infection by parasites preliminarily identified as Plasmodium circumflexum. Results from our study provide the first information on Plasmodium infection rates in Alaskan mosquitoes and evidence that Culiseta species may play a role in the transmission and maintenance of Plasmodium parasites in this region.     

Consequences of chronic infections with three different avian malaria lineages on reproductive performance of Lesser Kestrels (Falco naumanni)

We studied the consequences of chronic infections by three different lineages of avian malaria, two Plasmodium (RTSR1, LK6) and one Haemoproteus (LK2), on reproductive performance of Lesser Kestrels (Falco naumanni). Malaria infections in male and female parents had no effect on clutch size, hatching success or nesting success. However, when only successful nests were considered, we found that males parasitized by LK6 raised a lower number of fledglings, suggesting that the level of parental effort by males may be limited by this particular lineage of Plasmodium. This effect was not evident in females, probably due to the higher investment of males during the chick rearing period in this species. Overall, we have found that chronic stages of specific malaria lineages have certain negative consequences on host reproductive performance, highlighting the importance of considering genetic differences among malaria parasites to study their consequences on natural bird populations.     

Malaria infection increases bird attractiveness to uninfected mosquitoes

The epidemiology of vector‐borne pathogens is largely determined by the host‐choice behaviour of their vectors. Here, we investigate whether a Plasmodium infection renders the host more attractive to host‐seeking mosquitoes. For this purpose, we work on a novel experimental system: the avian malaria parasite Plasmodium relictum, and its natural vector, the mosquito Culex pipiens. We provide uninfected mosquitoes with a choice between an uninfected bird and a bird undergoing either an acute or a chronic Plasmodium infection. Mosquito choice is assessed by microsatellite typing of the ingested blood. We show that chronically infected birds attract significantly more vectors than either uninfected or acutely infected birds. Our results suggest that malaria parasites manipulate the behaviour of uninfected vectors to increase their transmission. We discuss the underlying mechanisms driving this behavioural manipulation, as well as the broader implications of these effects for the epidemiology of malaria.     

Haemosporidian infections in skylarks (<Emphasis Type="Italic">Alauda arvensis</Emphasis>): a comparative PCR-based and microscopy study on the parasite diversity and prevalence in southern Italy and the Netherlands

Changes in agricultural management have been identified as the most probable cause for the decline of Skylark (Alauda arvensis) populations in Europe. However, parasitic infections have not been considered as a possible factor influencing this process. Four hundred and thirty-four Skylarks from the Southern Italy and the Netherlands were screened for haemosporidian parasites (Haemosporida) using the microscopy and polymerase chain reaction (PCR)-based methods. The overall prevalence of infection was 19.5%; it was 41.8% in Italian birds and 8.3% in Dutch birds. The prevalence of Plasmodium spp. was 34.1% and 6.5% in Skylarks from Italy and Netherlands, respectively. Approximately 15% of all recorded haemosporidian infections were simultaneous infections both in Italian and Dutch populations. Six different mitochondrial cytochrome b (cyt b) lineages of Plasmodium spp. and three lineages of Haemoproteus tartakovskyi were found. The lineage SGS1 of Plasmodium relictum was the most prevalent at both study sites; it was recorded in 24.7% of birds in Italy and 5.5% in the Netherlands. The lineages SYAT05 of Plasmodium vaughani and GRW11 of P. relictum were also identified with a prevalence of <2% at both study sites. Two Plasmodium spp. lineages (SW2 and DELURB4) and three H. tartakovskyi lineages have been found only in Skylarks from Italy. Mitochondrial cyt b lineages SYAT05 are suggested for molecular identification of P. vaughani, a cosmopolitan malaria parasite of birds. This study reports the greatest overall prevalence of malaria infection in Skylarks during the last 100 years and shows that both Plasmodium and Haemoproteus spp. haemosporidian infections are expanding in Skylarks so it might contribute to a decrease of these bird populations in Europe.     

High prevalence and lineage diversity of avian malaria in wild populations of great tits (Parus major) and mosquitoes (Culex pipiens)

Avian malaria studies have taken a prominent place in different aspects of evolutionary ecology. Despite a recent interest in the role of vectors within the complex interaction system of the malaria parasite, they have largely been ignored in most epidemiological studies. Epidemiology of the disease is however strongly related to the vector's ecology and behaviour, and there is a need for basic investigations to obtain a better picture of the natural associations between Plasmodium lineages, vector species and bird hosts. The aim of the present study was to identify the mosquito species involved in the transmission of the haemosporidian parasites Plasmodium spp. in two wild populations of breeding great tits (Parus major) in western Switzerland. Additionally, we compared Plasmodium lineages, based on mitochondrial DNA cytochrome b sequences, between the vertebrate and dipteran hosts, and evaluated the prevalence of the parasite in the mosquito populations. Plasmodium spp. were detected in Culex pipiens only, with an overall 6.6% prevalence. Among the six cytochrome b lineages of Plasmodium identified in the mosquitoes, three were also present in great tits. The results provide evidence for the first time that C. pipiens can act as a natural vector of avian malaria in Europe and yield baseline data for future research on the epidemiology of avian malaria in European countries.     

Climate change increases the risk of malaria in birds

Malaria caused by Plasmodium parasites is one of the worst scourges of mankind and threatens wild animal populations. Therefore, identifying mechanisms that mediate the spread of the disease is crucial for both human health and conservation. Human‐induced climate change has been hypothesized to alter the geographic distribution of malaria pathogens. As the earth warms, arthropod vectors may display a general range expansion or may enjoy longer breeding season, both of which can enhance parasite transmission. Moreover, Plasmodium species may directly benefit for elevating temperatures, which provide stimulating conditions for parasite reproduction. To test for the link between climate change and malaria prevalence on a global scale for the first time, I used long‐term records on avian malaria, which is a key model for studying the dynamics of naturally occurring malarial infections. Following the variation in parasite prevalence in more than 3000 bird species over seven decades, I show that the infection rate by Plasmodium is strongly associated with temperature anomalies and has been augmented with accelerating tendency during the last 20 years. The impact of climate change on malaria prevalence varies across continents, with the strongest effects found for Europe and Africa. Migration habit did not predict susceptibility to the escalating parasite pressure by Plasmodium. Consequently, wild birds are at an increasing risk of malaria infection due to recent climate change, which can endanger both naïve bird populations and domesticated animals. The prevailing avian example may provide useful lessons for understanding the effect of climate change on malaria in humans.     

Environmental,geographical and time-related impacts on avian malaria infections in native and introduced populations of house sparrows (Passer domesticus), a globally invasive species

Aim

The increasing spread of vector-borne diseases has resulted in severe health concerns for humans, domestic animals and wildlife, with changes in land use and the introduction of invasive species being among the main possible causes for this increase. We explored several ecological drivers potentially affecting the local prevalence and richness of avian malaria parasite lineages in native and introduced house sparrows (Passer domesticus) populations.

Location

Global.

Time period

2002–2019.

Major taxa studied

Avian Plasmodium parasites in house sparrows.

Methods

We analysed data from 2,220 samples from 69 localities across all continents, except Antarctica. The influence of environment (urbanization index and human density), geography (altitude, latitude, hemisphere) and time (bird breeding season and years since introduction) were analysed using generalized additive mixed models (GAMMs) and random forests.

Results

Overall, 670 sparrows (30.2%) were infected with 22 Plasmodium lineages. In native populations, parasite prevalence was positively related to urbanization index, with the highest prevalence values in areas with intermediate urbanization levels. Likewise, in introduced populations, prevalence was positively associated with urbanization index; however, higher infection occurred in areas with either extreme high or low levels of urbanization. In introduced populations, the number of parasite lineages increased with altitude and with the years elapsed since the establishment of sparrows in a new locality. Here, after a decline in the number of parasite lineages in the first 30 years, an increase from 40 years onwards was detected.

Main conclusions

Urbanization was related to parasite prevalence in both native and introduced bird populations. In invaded areas, altitude and time since bird introduction were related to the number of Plasmodium lineages found to be infecting sparrows.     

The influence of ecological factors on mosquito abundance and occurrence in Galápagos

We sampled mosquitoes across 18 sites established at different elevations and stretching from the north to the south of Isla Santa Cruz, Galápagos. Two commonly occurring species, Ae. taeniorhynchus and Cx. quinquefasciatus, were collected along with environmental variables characteristic of the trapping sites to assess their influence on mosquito abundance and occurrence in the dry season of 2015. We captured Ae. taeniorhynchus at 14 out of 18 sites and Cx. quinquefasciatus at low and high elevation sites on Santa Cruz. We utilized two generalized linear models; the first assessed the influence of environmental variables on abundances of Ae. taeniorhynchus and the second assessed the influence of these variables on the presence of Cx. quinquefasciatus. Populations of both mosquito species declined with elevation. Rainfall data were limited, as we sampled during the dry season of 2015. Distance to mangroves and maximum humidity were significant in influencing the abundance of Ae. taeniorhynchus, while maximum humidity was found to significantly influence the presence of Cx. quinquefasciatus. Both species occurred in sites where temperature, precipitation, and humidity should allow for mosquito development as well as parasitic development of the protozoan parasites that cause avian malaria. Further research involving year‐round sampling of mosquitoes and accompanying meteorological data as well as experimental studies on vector competence are required to understand disease dynamics of parasites such as avian malaria in Galápagos.     

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.     

Local parasite lineage sharing in temperate grassland birds provides clues about potential origins of Galapagos avian Plasmodium

Oceanic archipelagos are vulnerable to natural introduction of parasites via migratory birds. Our aim was to characterize the geographic origins of two Plasmodium parasite lineages detected in the Galapagos Islands and in North American breeding bobolinks (Dolichonyx oryzivorus) that regularly stop in Galapagos during migration to their South American overwintering sites. We used samples from a grassland breeding bird assemblage in Nebraska, United States, and parasite DNA sequences from the Galapagos Islands, Ecuador, to compare to global data in a DNA sequence registry. Homologous DNA sequences from parasites detected in bobolinks and more sedentary birds (e.g., brown‐headed cowbirds Molothrus ater, and other co‐occurring bird species resident on the North American breeding grounds) were compared to those recovered in previous studies from global sites. One parasite lineage that matched between Galapagos birds and the migratory bobolink, Plasmodium lineage B, was the most common lineage detected in the global MalAvi database, matching 49 sequences from unique host/site combinations, 41 of which were of South American origin. We did not detect lineage B in brown‐headed cowbirds. The other Galapagos‐bobolink match, Plasmodium lineage C, was identical to two other sequences from birds sampled in California. We detected a close variant of lineage C in brown‐headed cowbirds. Taken together, this pattern suggests that bobolinks became infected with lineage B on the South American end of their migratory range, and with lineage C on the North American breeding grounds. Overall, we detected more parasite lineages in bobolinks than in cowbirds. Galapagos Plasmodium had similar host breadth compared to the non‐Galapagos haemosporidian lineages detected in bobolinks, brown‐headed cowbirds, and other grassland species. This study highlights the utility of global haemosporidian data in the context of migratory bird–parasite connectivity. It is possible that migratory bobolinks bring parasites to the Galapagos and that these parasites originate from different biogeographic regions representing both their breeding and overwintering sites.     

Interannual patterns of avian diseases in wild New Zealand avifauna near conservation areas

The past few years have seen a noticeable increase in the emergence of infectious diseases in wildlife, especially vector-borne diseases, presenting a challenge for the conservation of endangered species. One such vector-borne disease, avian malaria (Plasmodium spp.) is on the rise in New Zealand avifauna, threatening bird populations that are among the most extinction-prone in the world. Furthermore, recent reports have outlined an increase in deaths of native iconic bird species specifically due to this disease. In order to help manage breakouts of this pathogen at a local scale, we need a better understanding of potential drivers of the emergence of avian malaria in wild New Zealand avifauna. Here, we set to test the role of climatic drivers in synchronizing contacts between avian hosts and vectors, assess the temporal stability of transmission dynamics between years, and determine the role of introduced species in causing spill-over of this pathogen towards native species. Our study focused on three sites that were sampled regularly during two consecutive years in the austral summer, each site being adjacent to a breeding colony of Yellow-eyed penguins (Megadyptes antipodes). Our results reveal an overall temporal stability of avian malaria incidence patterns, with a decrease in infection throughout the austral summer for both sampled years. Moreover, we highlight a phylogenetic signal among sampled bird species, with introduced species being more heavily infected by avian malaria than their native counterparts. In contrast, we found no effect of the two climatic drivers investigated, temperature and rainfall, on mosquito abundance. Our results suggest a strong effect of alien species acting as reservoirs for diseases spilling-over towards immunologically naïve species, and provide conservation managers with a critical timeframe to control avian malaria breakouts.     

The distribution of mosquitoes across an altitudinal gradient in the Galapagos Islands

An avian malaria parasite (genus Plasmodium) has been detected consistently in the Galapagos Penguin (Spheniscus mendiculus) and less frequently in some passerines. We sampled three resident mosquito species (Aedes taeniorhynchus, Culex quinquefasciatus, and Aedes aegypti) using CDC light and gravid traps on three islands in 2012, 2013, and 2014. We sampled along altitudinal gradients to ask whether there are mosquito‐free refugia at higher elevations as there are in Hawaii. We captured both Ae. taeniorhynchus and Cx. quinquefasciatus at all sites. However, abundances differed across islands and years and declined significantly with elevation. Aedes aegypti were scarce and limited to areas of human inhabitation. These results were corroborated by two negative binomial regression models which found altitude, year, trap type, and island as categorized by human inhabitation to be significant factors influencing the distributions of both Ae. taeniorhynchus and Cx. quinquefasciatus. Annual differences at the highest altitudes in Isabela and Santa Cruz indicate the lack of a stable highland refuge if either species is found to be a major vector of a parasite, such as avian malaria in Galapagos. Further work is needed to confirm the vector potential of both species to understand the disease dynamics of avian malaria in Galapagos.     

A PCR test for avian malaria in Hawaiian birds

The decline of native Hawaiian forest birds since European contact is attributed to factors ranging from habitat destruction to interactions with introduced species. Remaining populations of Hawaiian honeycreepers (Fringillidae: Drepanidinae) are most abundant and diverse in high elevation refuges above the normal range of disease-carrying mosquitoes. Challenge experiments suggest that honeycreepers are highly susceptible to avian malaria (Plasmodium sp.) but resistance exists in some species. In order to detect low levels of malarial infection and quantify prevalence of Plasmodium in high elevation natural populations of Hawaiian birds, a polymerase chain reaction (PCR) based diagnostic test was developed that identifies rRNA genes of Plasmodium in avian blood samples. Quantitative competitive PCR (QC-PCR) experiments indicate that the detection limit of our test is an order of magnitude greater than that reported for human malaria DNA blot tests. Compared with standard histological methods, the PCR test detected a higher prevalence of diseased birds at mid-elevations. Malaria was detected in three species of native birds living in a high elevation wildlife refuge on the island of Hawaii and in four species from Maui. Our results show that avian malaria is more widespread in Hawaiian forests than previously thought, a finding that has important conservation implications for these threatened species.     

Avian malaria on Madagascar: prevalence,biodiversity and specialization of haemosporidian parasites

Previous studies about geographic patterns of species diversity of avian malaria parasites and others in the Order Haemosporida did not include the avian biodiversity hotspot Madagascar. Since there are few data available on avian malaria parasites on Madagascar, we conducted the first known large-scale molecular-based study to investigate their biodiversity. Samples (1067) from 55 bird species were examined by a PCR method amplifying nearly the whole haemosporidian cytochrome b gene (1063?bp). The parasite lineages found were further characterized phylogenetically and the degree of specialization was determined with a newly introduced host diversity index (Hd). Our results demonstrate that Madagascar indeed represents a biodiversity hotspot for avian malaria parasites as we detected 71 genetically distinct parasite lineages of the genera Plasmodium and Haemoproteus. Furthermore, by using a phylogenetic approach and including the sequence divergence we suspect that the detected haemosporidian lineages represent at least 29 groups i.e. proposed species. The here presented Hd values for each parasite regarding host species, genus and family strongly support previous works demonstrating the elastic host ranges of some avian parsites of the Order Haemosporida. Representatives of the avian parasite genera Plasmodium and Leucocytozoon tend to more often be generalists than those of the genus Haemoproteus. However, as demonstrated in various examples, there is a large overlap and single parasite lineages frequently deviate from this rule.     

Nonspecific patterns of vector, host and avian malaria parasite associations in a central African rainforest

Malaria parasites use vertebrate hosts for asexual multiplication and Culicidae mosquitoes for sexual and asexual development, yet the literature on avian malaria remains biased towards examining the asexual stages of the life cycle in birds. To fully understand parasite evolution and mechanism of malaria transmission, knowledge of all three components of the vector-host-parasite system is essential. Little is known about avian parasite-vector associations in African rainforests where numerous species of birds are infected with avian haemosporidians of the genera Plasmodium and Haemoproteus. Here we applied high resolution melt qPCR-based techniques and nested PCR to examine the occurrence and diversity of mitochondrial cytochrome b gene sequences of haemosporidian parasites in wild-caught mosquitoes sampled across 12 sites in Cameroon. In all, 3134 mosquitoes representing 27 species were screened. Mosquitoes belonging to four genera (Aedes, Coquillettidia, Culex and Mansonia) were infected with twenty-two parasite lineages (18 Plasmodium spp. and 4 Haemoproteus spp.). Presence of Plasmodium sporozoites in salivary glands of Coquillettidia aurites further established these mosquitoes as likely vectors. Occurrence of parasite lineages differed significantly among genera, as well as their probability of being infected with malaria across species and sites. Approximately one-third of these lineages were previously detected in other avian host species from the region, indicating that vertebrate host sharing is a common feature and that avian Plasmodium spp. vector breadth does not always accompany vertebrate-host breadth. This study suggests extensive invertebrate host shifts in mosquito-parasite interactions and that avian Plasmodium species are most likely not tightly coevolved with vector species.     

Host‐seeking activity and avian host preferences of mosquitoes associated with West Nile virus transmission in the northeastern U.S.A.

Mosquito host‐seeking activity was studied using a custom‐designed trap to explore: (1) at which time interval of the night adult mosquito abatement would be most effective, and (2) if there exists an avian‐specific host‐seeking preference. Overnight trials using traps baited with dry ice showed that Aedes taeniorhynchus (Wiedemann) was most active at dusk and was then captured throughout the night. In contrast, Culex spp. (Cx. pipiens (Linnaeus) and Cx. restuans (Theobald) delayed most activity until about two h after dusk and were then captured through the night. This pattern suggests that management activities directed at adult Culex spp. would be most effective if initiated well after sunset. Mosquito capture rates in traps baited with birds in net bags were significantly greater than those with empty net bags, indicating that mosquitoes were attracted to the birds and not incidentally being sucked in by the custom trap's strong fan motor (Wilcoxon matched‐pairs signed‐ranks test, n= 24, t= 30, p < 0.05). Regression analysis showed that bird weight influenced mosquito attraction (r²= 0.21, p= 0.02). Trials with paired traps that contained different native bird species showed that Gray Catbirds, Dumatella carolinensis, attracted more mosquitoes than the heavier Northern Cardinals, Cardinalis cardinalis (paired samples t‐test, t= 2.58, df= 7, p= 0.04). However, attractiveness did not differ substantially among bird species, and Gray Catbirds did not attract more mosquitoes than all other birds combined as a group. American Robins, Turdus migratorius (n = 4) were comparable in attractiveness to other bird species, but not enough American Robins were captured for a comprehensive study of mosquito avian preference.