Journal of medical entomology最新文献

Tick-borne diseases in humans and animals have increased prevalence across the United States. To understand risk factors underlying tick-borne diseases it is useful to conduct regular surveillance and monitoring of ticks and the pathogens they carry, in a sustained and effective manner. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, this study aims to summarize the previously used methods for active surveillance of ticks and tick-borne pathogens, identify the existing knowledge gaps in ongoing surveillance, and highlight and guide the mechanisms required to inform those gaps for more effective and sustainable future surveillance efforts. After screening 2,500 unique studies between 1944 and 2018, we found 646 articles that performed active surveillance of hard ticks and/or their associated tick-borne pathogens of public health importance within the United States. An additional 103 articles were included for the 2019 to 2023 period. Active surveillance has been performed in ~42% of the counties (1944 to 2018) and ~23% of the counties (2019 to 2023) within the contiguous US, and states with the most coverage are in the Northeast, Upper Midwest, and along the West coast. The most reported tick was Ixodes scapularis (195 studies) and most commonly reported pathogen was Borrelia burgdorferi (143 studies). Overall, surveillance efforts have increased and become more diversified, and methods of tick and tick-borne pathogens testing have undergone changes, but those efforts are mainly concentrated in focal regions of a county. Future surveillance efforts should follow Centers for Disease Control and Prevention guidelines and target areas of United States with scarce reports of active surveillance and build collaborations and resources to increase surveillance.

In this study, we present an analysis of the male reproductive system and spermatozoa of Anopheles darlingi Root, 1926, the primary malaria vector in Brazil. The reproductive system consists of a pair of unifollicular testes, deferent ducts, a muscular ejaculatory duct, and a pair of accessory glands. The average spermatozoa length was 188 µm, with a continuous variation from 92 to 246 µm. This significant variation may be associated with the mosquito's copulatory behavior, in which females are monandrous. This scenario may reduce the selective pressure for uniformity of male gametes in this species.

Sarcosaprophagous flies are essential for the degradation of organic matter and nutrient cycling, which are critical for ecosystem health. This study assesses how anthropization influences fly assemblage diversity, abundance, and their role in organic matter degradation across different areas. Three types of substrates were used: raw chicken viscera (CV), cow dung (CD), and cooked noodles with raw eggs (NE), in areas with low (LA) and high (HA) anthropization. In each area, 5 baited traps per substrate, which allowed fly entry, and 3 unexposed controls were set. The experiment was conducted 3 times, totaling 90 baited traps and 36 controls. Flies that emerged were collected on day 21. Substrate weights were recorded at the start and end of each trial. The highest abundance of species that emerged was observed in CV-HA, while the greatest species richness was recorded in CV-LA. Significant differences in fly assemblages were observed between areas. Greater degradation of CV was recorded in HA, whereas CD showed a significant difference with control traps only in LA. Substrate degradation was positively related with fly abundance in CV-HA, and with both fly abundance and species richness in CD-LA. This study highlights the pivotal role that sarcosaprophagous flies play in organic matter decomposition, health risks related to organic waste accumulation, and nutrient cycling across anthropogenically altered environments, revealing significant variations in decomposition rates and the composition of fly assemblages. Also, we emphasize the potential of sarcosaprophagous flies as bioindicators for assessing anthropogenic impacts on ecosystems.

The western blacklegged tick, Ixodes pacificus Cooley and Kohls, is a significant public health concern due to its capacity to vector Borrelia burgdorferi sensu stricto (Spirochaetales: Spirochaetaceae), the causative agent of Lyme disease. To determine the influence of elevation on the seasonality and abundance of Ixodes pacificus nymphs in the Sierra Nevada foothills of California, we used a standardized flagging procedure to sample nymphs from rocks and logs at 16 sites during 2018 to 2020. We sampled a total of 4,720 rocks and logs during 168 surveillance events and collected 1,469 I. pacificus nymphs. Nymphal abundance was similar on rock and log substrates. Tick abundance and seasonality varied by elevation, with lower elevation sites exhibiting higher nymphal abundance and earlier seasonal activity. Nymphal activity started later and persisted longer into the summer months at higher elevation sites. Nymphal abundance on rocks and logs was not predictive of adult abundance the following year, as estimated by drag sampling for adult ticks along hiking trails within the nymph sampling areas. Overall, 4.9% and 1.4% of the tested nymphs were infected with Borrelia burgdorferi s.l. and B. miyamotoi, respectively. We found no relationship between elevation and B. burgdorferi s.l. infection prevalence, although fewer nymphs were tested from higher elevation sites. These findings advanced our understanding of I. pacificus nymphal abundance and distribution and helped improve assessment of public health risks associated with tick exposure in the Sierra Nevada foothills.

Comparative studies of the microbiota in whole-body mosquitoes from natural populations and laboratory-reared specimens are scarce, particularly in tropical countries like Colombia, where understanding microbial patterns is critical for effective disease control and vector management. This study examines the bacterial microbiota of Aedes aegypti by comparing field-collected mosquitoes from 3 Colombian regions (Southern Amazon, Central Andean region, and Northern Caribbean coast) with laboratory strains (Rockefeller, Otanche, and Tolima). These regions are highly endemic for dengue and are associated with lineage 1 of Ae. aegypti, known for its elevated vector competence. Using next-generation sequencing of the 16S rRNA gene with Illumina technology, we found that field-collected mosquitoes exhibited significantly higher alpha and beta diversity compared to laboratory-reared specimens. Field mosquitoes were enriched with bacterial families such as Acetobacteraceae, Lactobacillaceae, and Bacillaceae, while laboratory mosquitoes showed a greater abundance of Enterobacteriaceae. Differential abundance analysis revealed that Acetobacter and Bacillus predominated in field mosquitoes, whereas Asaia, Cedacea, and Chryseobacterium were more common in laboratory specimens. Notably, Pseudomonas and Acinetobacter were consistently abundant across all samples. Our findings suggest that environmental factors, such as habitat and diet, significantly influence the bacterial composition and diversity of Ae. aegypti in Colombia. Future research should further explore how these factors, alongside genetic components, shape mosquito-microbiota interactions and their implications for disease transmission and vector competence.

Filarial nematodes are parasitic roundworms transmitted by mosquitoes that can cause morbidity and mortality for their human and animal hosts. The filariae community, specifically infection prevalence of heartworm, Dirofilaria immitis (Filarioidea: Onchocercidae) (Leidy), and its primary mosquito vector species, has not been described in Connecticut since 1977. In light of the recent invasion and establishment of an important filariasis vector, Aedes albopictus (Diptera: Culicidae) (Skuse), we used molecular-based sequencing methods to identify filarial species infecting field-caught mosquitoes in Connecticut, United States. The filarial parasites identified include D. immitis, Aproctella sp., and Setaria sp. (Filarioidea: Setariidae). The total minimum infection rate for D. immitis for all mosquito species tested in 2020 was 0.97 [0.56 to 1.56] and in 2021 was 1.48 [0.93 to 2.24]. Aedes albopictus had the highest infection prevalence compared to other species during both years. We determined a low but persistent mosquito infection prevalence for D. immitis and suggest that Ae. albopictus is likely to be the primary vector in the region. Aproctella sp. and Setaria sp. had lower burdens compared to D. immitis. Persistent mosquito infection with filarial parasites, particularly in invasive species, poses a risk to veterinary and public health.

Mosquito-borne disease (MBD) incidence is increasing in the United States (U.S.), presenting an evolving health threat. Assessments of public perceptions have revealed limited awareness of MBDs among the U.S. population. Our team used focus groups to gain an in-depth understanding of risk perceptions regarding mosquito exposure and pesticide use, and benefit perceptions and motivators for bite prevention strategies. A total of 37 individuals participated in focus groups across 3 states: New Jersey (n = 14), New York (n = 15), and Massachusetts (n = 8). Most participants were unfamiliar with public mosquito control services and felt they were not at high exposure risk to any MBDs. Overall, participants were supportive of investing public funds for mosquito surveillance. However, participants across all focus groups expressed concerns over ecosystem health and long-term consequences of pesticide use for mosquito control. Participants in every focus group referenced a risk assessment that weighed the risk of MBD exposure against the use of chemical control: once participants perceived MBDs as negatively impacting human and/or animal health in their area, sentiment swung largely to supporting the use of pesticides. In the absence of an obvious MBD threat, participants preferred nonchemical control interventions. Participants felt communication from mosquito control agencies should be accessible, disseminated across multiple venues, and should include instructions for the public during spray events, resources for individual bite prevention, and information on control products used. Our research results can inform the development of improved, evidence-based MBD outreach and educational resources that are acceptable, actionable, and relevant to Northeast communities.

Competition between mosquito species during the larval phase is a well-established mechanism structuring container mosquito communities, with invasive species often outperforming natives. We assessed the competitive outcome between 2 species that occur on the island of Puerto Rico, the historic invasive Aedes aegypti (L.) and the endemic Aedes mediovittatus (Coquillett) (Diptera: Culicidae). Trials were conducted under intra- and interspecific densities crossed with 2 amounts of 4 different leaf types serving as detrital resources for developing larvae; leaf types were representative of either urban or rural locations. Response variables included survival, male and female mass and development time, and a composite index of population growth (λ'). We also measured tannin levels in detrital environments, a secondary metabolite that can negatively influence mosquito development and survival. The co-occurrence of Ae. aegypti and Ae. mediovittatus generally did not affect survival or population growth of Ae. mediovittatus, however the converse was not true. Specifically, Ae. aegypti suffered lower survival and lower population growth in the presence of Ae. mediovittatus compared to when it was alone. Tannin concentrations did not correspond to competitive outcomes, as the highest tannin levels occurred under the detrital conditions where mosquitoes had highest growth and survival, with no evidence of differences between urban or rural leaf types. This is the first study to quantify the competitive outcomes between these species, both of which are part of the dengue transmission cycle on the island, and our findings suggest that Ae. mediovittatus is capable of outcompeting Ae. aegypti under some resource environments.

Mosquito control using pyrethrins and synthetic pyrethroids (PSP) is important for preventing vector-borne diseases. Although the benefits associated with PSP use are well-documented, public concern exists regarding potential human adverse health effects. The aim of this scoping review was to describe adverse human health effects associated with PSP use for community adult mosquito control. A literature search using the databases MEDLINE, EMBASE, Agricultural and Environmental Science Collection, CAB Abstracts, and Scopus obtained 6,154 original peer-reviewed articles published during 1 January 2000 to 22 May 2024. Articles were independently reviewed for inclusion using predetermined exclusion and inclusion criteria. Data were extracted from 10 included articles. Study designs included cohort (n = 5), cross-sectional (n = 2), and risk assessment (n = 4). One article included 2 study designs. Of the cohort studies, one was prospective and the remainder were retrospective. A causal relationship between PSP application for adult mosquito control and adverse human health impacts was not identified. No increases in acute health manifestations were reported. The 4 risk assessments estimated that PSP exposures were not above the regulatory level of concern; a meta-analysis determined the likelihood of PSP exposures exceeding the regulatory level of concern was <0.0001. The limited evidence indicated that PSP applied appropriately for control of nuisance mosquitoes or mosquitoes that transmit arboviruses do not pose acute or chronic human health risks. Continued investigation into potential human health impacts of PSP would help inform guidelines for adult mosquito control and help inform public health decision making.

Chagas disease is one of the most important vector-borne diseases in Mexico. Triatoma pallidipennis (Stål) is one of the most epidemiologically important vector species. Despite being classified as a single species, various studies (molecular, morphometric, and biological) on populations across its distribution suggested it is composed of a group of cryptic species. This study examined reproductive isolation among 5 populations of T. pallidipennis originating from the western, southern, and central regions of Mexico to help clarify the potential existence of a cryptic species complex of T. pallidipennis in Mexico. A generation of hybrids was analyzed for fertility and fecundity. Fertility rates varied from 50% to 100% in the parental crosses and from 20% to 100% in the F1 × F1 crosses. Fecundity ranged from 1.4 to 3.2 eggs/female/day in the parental crosses, which decreased to 0.9-2.9 in the F1 × F1 crosses (except in Jalisco × Morelos). The fertility of the eggs ranged from 61.4% to 85.4% in the parental crosses, dropping to 44% to 90.1% in some F1 × F1 crosses, indicating partial reproductive isolation among these populations.