Journal of medical entomology最新文献

There is growing interest in insecticide resistance in the mosquito, Aedes albopictus (Skuse), as its potential for spreading diseases is increasing as urbanization and control efforts intensify. Here we review the presence and diversity of mutations in the voltage-sensitive sodium channel (Vssc) gene associated with pyrethroid resistance and report on additional surveys of these mutations in new populations with an analysis of their spread. The known diversity of these mutations has increased in recent years including the identification of 26 non-synonymous mutations, although phenotypic data associating mutations with resistance remain limited. We provide data on mutations in several new locations including those in Timor Leste, Indonesia, and Vanuatu. We use population genomic data from ddRAD analyses of target populations with the 1534C mutation to identify single nucleotide polymorphisms (SNPs) associated with the mutant to test for clustering of SNPs based on the presence of the 1534C mutation rather than population origin. Our findings suggest spread of resistance alleles via genetic invasion, which is further supported by patterns from a genome-wide principal components analysis. These data point to movement of resistance alleles across wide areas with likely impacts on local control options.

The field of veterinary entomology is dominated by research concerning insects and arthropods that negatively impact the health of domestic animals. A curated selection of peer-reviewed research which was highlighted at the 2022 Joint Meeting between the Entomological Society of America, the Entomological Society of Canada, and the Entomological Society of British Columbia, which prioritized exploring entomology through the lens of art, science, and culture are summarized. Articles are categorized into (i) biting and non-biting flies, (ii) ectoparasites, and (iii) review articles, with the overall goal of showcasing innovative methodologies, addressing overlooked questions in veterinary entomology, and highlighting comprehensive reviews. While not exhaustive, the selected studies represent a myriad of arthropods, methodologies, and perspectives, to inspire future scientists with diverse research avenues and emphasize the continual evolution and importance of entomological studies in today's world.

In efforts to intensify malaria control through vector control and hasten the progress towards elimination, the impact of control interventions needs to be evaluated. This requires sampling vector population using appropriate trapping methods. The aim of this article is to critically review methods of sampling malaria vectors and their reliability in estimating entomological indicators of malaria transmission in Africa. The standard methods are human landing catch (HLC), pyrethrum spray catch, and pit shelter for sampling host-seeking, indoor resting, and outdoor resting malaria vectors, respectively. However, these methods also have drawbacks such as exposure of collectors to infective mosquito bites, sampling bias, and feasibility issue. Centers for Disease Control and Prevention (CDC) light traps placed beside human-occupied bed nets have been used as an alternative to the HLC for sampling host-seeking malaria vectors. Efforts have been made to evaluate the CDC light traps against HLC to generate a conversion factor in order to use them as a proxy estimator of human biting rate and entomological inoculation rates in Africa. However, a reproducible conversion factor was not found, indicating that the trapping efficiency of the CDC light traps varies between different geographical locations. Several other alternative traps have also been developed and evaluated in different settings but most of them require further standardization. Among these, human-baited double net trap/CDC light trap combination and mosquito electrocuting trap have the potential to replace the HLC for routine malaria vector surveillance. Further research is needed to optimize the alternative sampling methods and/or develop new surveillance tools based on vector behavior.

Biting midges in the genus Culicoides Latreille (Diptera: Ceratopogonidae) are known to transmit many pathogens of veterinary and medical concern. Although much work has been done globally and in certain regions of North America, Culicoides spp. research in rural Appalachia is limited. To begin characterizing the distribution and community structure of Culicoides spp. in Appalachia, we surveyed 2 distinct sites in the Ridge and Valley ecoregion of northeastern Tennessee, USA, from April 2021-September 2021. Culicoides spp. were sampled using 2 methods: Centers for Disease Control ultraviolet LED light traps and potential larval habitat substrate collection (coupled with water chemistry values). Site 1 was dominated by natural features, and Site 2 was a beef cattle operation. During 96 trap nights, a total of 1,568 Culicoides were collected, representing 24 species. Site 1 yielded the highest diversity, with 24 species, while Site 2 yielded 12 species. Overall, the most abundant species in light traps were C. stellifer Coquillett (44%), C. bergi Cochrane (18%), C. haematopotus Malloch (12%), and C. debilipalpis Lutz (11%). From substrate sampling, 8 species were identified. Culicoides haematopotus was the most abundant and was collected during each sampling period. Water chemistry values taken at the time of substrate collection were not significantly related to which Culicoides spp. emerged from a given substrate. Our results indicate a diverse community of Culicoides spp. in our study area, however, further work is needed to identify Culicoides species composition across a variety of landscapes in Appalachia and inform research on vector presence and associated vector disease dynamics.

The emergence of insecticide resistance in mosquitoes necessitates the exploration and validation of sustainable biological strategies for controlling mosquitoes in their natural habitats. We assessed the predatory effect of Utricularia aurea Lour (Lamiales: Lentibulariaceae), an aquatic carnivorous plant found in the Indian subcontinent, Japan, and Australia, on 4 instars of Anopheles stephensi Liston, Culex quinquefasciatus Say, and Aedes aegypti Linn (Diptera: Culicidae), in the laboratory and field settings. In the laboratory setting, predation of larvae by U. aurea was highest during the first hour when it predated 45%, 61%, and 58% of first instars of An. stephensi, Cx. quinquefasciatus, and, Ae. aegypti, respectively, and, within 12 h, U. aurea preyed upon ~95% of the first, second, and third instars of the 3 mosquito species, ~80% of the fourth instars of An. stephensi and Ae. aegypti, and ~60% of fourth instars of Cx. quinquefasciatus. The predatory effect of U. aurea varied with mosquito species and instar. Broadly, predation risk declined with the increase of the instar size. In the field setting, at the end of 16 days, U. aurea predated 76% and 71% of the immature An. stephensi and Ae. aegypti, respectively. Our findings suggest U. aurea can be utilized as a potential biocontrol agent for controlling mosquito larvae in natural habitats; however, the current claim warrants additional investigations in a variety of natural habitats.

Malaria vector surveillance tools often incorporate features of hosts that are attractive to blood-seeking females. The recently developed host decoy trap (HDT) combines visual, thermal, and olfactory stimuli associated with human hosts and has shown great efficacy in terms of collecting malaria vectors. Synthetic odors and yeast-produced carbon dioxide (CO2) could prove useful by mimicking the human odors currently used in HDTs and provide standardized and easy-to-use olfactory attractants. The objective of this study was to test the attractiveness of various olfactory attractant cues in HDTs to capture malaria vectors. We compared 4 different odor treatments in outdoor field settings in southern Benin and western Burkina Faso: the standard HDT using a human, HDT with yeast-produced CO2, HDT with an artificial odor blend, and HDT with yeast-produced CO2 plus artificial odor blend. In both experimental sites, the standard HDT that incorporated a real human produced the greatest catch of Anopheles gambiae s.l (Diptera: Culicidae). The alternatives tested were still effective at collecting target vector species, although the most effective included CO2, either alone (Benin) or in combination with synthetic odor (Burkina Faso). The trap using synthetic human odor alone caught the fewest An. gambiae s.l. compared to the other baited traps. Both Anopheles coluzzii and Anopheles gambiae were caught by each trap, with a predominance of An. coluzzii. Synthetic baits could, therefore, represent a more standardized and easier-to-deploy approach than using real human odor baits for a robust vector monitoring strategy.

Mosquito-borne diseases can pose significant burdens. In many countries, they pose a risk to national economies and the well-being of humans and animals. To mitigate this, mosquito surveillance is crucial to assess the real and potential transmission of mosquito-borne diseases. Between 2020 and 2023, mosquito larvae were collected from both indoor and outdoor breeding sites in urban and rural areas of 4 municipalities of Santiago and Boavista Islands in Cabo Verde. Mosquitoes were identified morphologically and by polymerase chain reaction-based techniques that targeted the mitochondrial cytochrome C oxidase subunit I sequence. During this period, 6,825 breeding sites were assessed, and of 8,094 mosquito specimens screened, 194 specimens of Culex thalassius were identified for the first time in the country in 4 municipalities of Santiago and Boavista Islands. This new finding highlights the importance of including entomological surveillance in health systems. Although this species has only been detected on a few islands, it is important to continuously monitor it to determine its distribution, spread/dispersal, density, and potential involvement in pathogen transmission.

The Pacific Coast tick (Dermacentor occidentalis Marx, 1892) is a frequently encountered and commonly reported human-biting tick species that has been recorded from most of California and parts of southwestern Oregon, southcentral Washington, and northwestern Mexico. Although previous investigators have surveyed populations of D. occidentalis for the presence of Rickettsia species across several regions of California, populations of this tick have not been surveyed heretofore for rickettsiae from Baja California, Oregon, or Washington. We evaluated 1,367 host-seeking, D. occidentalis adults collected from 2015 to 2022 by flagging vegetation at multiple sites in Baja California, Mexico, and Oregon and Washington, United States, using genus- and species-specific assays for spotted fever group rickettsiae. DNA of Rickettsia 364D, R. bellii, and R. tillamookensis was not detected in specimens from these regions. DNA of R. rhipicephali was detected in D. occidentalis specimens obtained from Ensenada Municipality in Baja California and southwestern Oregon, but not from Washington. All ompA sequences of R. rhipichephali that were amplified from individual ticks in southwestern Oregon were represented by a single genotype. DNA of the Ixodes pacificus rickettsial endosymbiont was amplified from specimens collected in southwestern Oregon and Klickitat County, Washington; to the best of our knowledge, this Rickettsia species has never been identified in D. occidentalis. Collectively, these data are consistent with a relatively recent introduction of Pacific Coast ticks in the northernmost extension of its recognized range.

Three Asian longhorned ticks (Haemaphysalis longicornis) were collected on Staten Island, Richmond County, New York, in 2014-2015 as part of a tick-borne disease surveillance program conducted by the New York City Department of Health and Mental Hygiene and the Defense Centers of Public Health - Aberdeen Tick-Borne Disease Laboratory. These records mark the earliest known occurrence of H. longicornis in New York State outside of quarantine areas, predating previously reported detections by several years. Robust populations of H. longicornis were collected in subsequent years at the Staten Island site where these few ticks were found, demonstrating that small infestations have the potential to proliferate quickly. Haemaphysalis longicornis is a 3-host ixodid tick native to eastern Asia but now established in the United States, as well as Australasia and several Pacific islands. Although H. longicornis has not yet been associated with human disease transmission in the United States, it warrants attention as a potential vector, as it is demonstrated to harbor various pathogens of medical and veterinary interest across its native and introduced range.

Forest management practices designed to meet varied landowner objectives affect wildlife habitat and may interrupt the life-cycle stages of disease vectors, including the black-legged tick, Ixodes scapularis Say (Acari: Ixodidae). Ixodes scapularis transmits multiple pathogens including Borrelia burgdorferi, the causative agent of Lyme disease, which is the most common tick-borne disease in the United States. There is evidence that a range of active forest management practices (e.g., invasive plant removal, prescribed burning) can alter tick densities and pathogen transmission. However, few studies have investigated relationships between forest stand structural variables commonly manipulated by timber harvesting and tick ecology. Foresters may harvest timber to create certain forest structural conditions like the mean number of trees, or basal area, per hectare. This study used a spatially replicated experiment in a blocked design to compare forest stands with a range of overstory structures and document variations in the midstory, understory, and forest floor, as well as microclimate conditions within tick off-host habitat. Greater numbers of trees or basal area per hectare correlated with greater canopy closure but less understory cover, stabilized microclimate temperature, higher microclimate humidity, and greater I. scapularis nymph densities. A random forest model identified understory forest structure as the strongest predictor of nymph densities. There was no relationship between the number of trees or basal area per hectare and daily deer (Odocoileus virginianus Zimmermann) activity or nymphal infection prevalence. These findings provide a deeper understanding of tick-habitat associations within a forest stand and have the potential to inform forest management decisions.