Journal of medical entomology最新文献

Blow flies (Diptera: Calliphoridae) play an important role in forensic entomology (using insects and other arthropods to criminal investigations). An early step for this application is accurate species identification. The 2 main approaches are morphological and molecular, but each has its limitations, making it necessary to use alternative or supplementary tools. Since outline-based geometric morphometrics (GM) is widely applied with insect identification, this study examined this method for species identification of 800 third-instar larvae of 8 blow fly species Chrysomya chani Kurahashi, Chrysomya megacephala (Fabricius), Chrysomya (Ceylonomyia) nigripes Aubertin, Chrysomya pinguis (Walker), Chrysomya (Achoetandrus) rufifacies (Macquart), Hemipyrellia ligurriens (Wiedemann), Lucilia cuprina (Wiedemann), and Lucilia porphyrina (Walker). Successful classification based on the cephaloskeleton demonstrated high reclassification scores ranging from 89% to 100%. This indicates that outline-based GM of the larval cephaloskeleton contour offers a significant advantage in identifying fly specimens. It can complement traditional methods, especially when encountering certain limitations-such as incomplete or damaged larvae-and can also help lower costs associated with molecular analyses.

Surveillance of tick-borne pathogens (TBPs) harbored by ticks and a variety of human and non-human hosts can help track the range expansion of vectors and the spread of TBPs. Countries with similar geographic landscapes, reservoir hosts, weather patterns, animal movements, and economic activities might have comparable tick and TBPs; monitoring these can help with spillover prevention and timely disease prevention efforts. We compared the countries of India, Pakistan, Sri Lanka, and Ethiopia to determine (i) tick surveillance methods, (ii) methods of tick and TBP detection, (iii) areas where important tick species are present, and (iv) areas where crucial TBPs are present. We compared these countries specifically due to comparable agricultural and animal husbandry practices, socioeconomic conditions, diversity of landscapes, flora, and fauna, transboundary movements, and relative proximity, which dictates the kinds of ticks present and conditions for pathogen dissemination. Surveillance gaps were identified, including underrepresentation of ecologically diverse or remote regions, limited human and wildlife sampling, and a lack of non-targeted pathogen detection approaches. Shared tick species (Rhipicephalus microplus, Haemaphysalis bispinosa, and Hyalomma anatolicum) and TBPs were observed across countries with similar livestock production and climates, suggesting parallel ecological drivers of tick and pathogen distribution. We discuss the geographic variation in the vector tick species, TBPs, mechanisms used for tick surveillance, and the need for integrated One Health surveillance. Future studies should delve into comparing ecological mechanisms occurring in multiple countries that might be driving the occurrence of zoonotic tick-borne diseases and prevention measures to reduce the burden of TBPs.

Mosquito-vectored disease remains a significant global public health threat. One of the most significant barriers to mosquito control is the evolution of insecticide resistance and limited number of available insecticide classes. Isoxazolines and meta-diamides are two classes of insecticides targeting the gamma-aminobutyric acid (GABA) channel, a target site currently under-utilized in mosquito adulticides. Topical assays were conducted on laboratory colonies of the yellow fever mosquito, Aedes aegypti L. (Diptera: Culicidae), and the common malaria mosquito, Anopheles quadrimaculatus Say (Diptera: Culicidae), with three isoxazolines: afoxolaner, fluralaner, and fluxametamide, the meta-diamide, broflanilide, and the pyrethroid deltamethrin, a commonly used and well-studied insecticide for adult mosquito control. The insecticides were tested against susceptible and pyrethroid resistant Ae. aegypti and susceptible An. quadrimaculatus. Broflanilide and afoxolaner were found to be the most and least toxic, respectively, and all five compounds were more toxic to Ae. aegypti than An. quadrimaculatus. Cross-resistance to afoxolaner, fluralaner, and fluxametamide, and broflanilide was low or not found in the pyrethroid resistant CKR strain. Age ratios were low to insignificant, suggesting no difference in toxicity between younger and older mosquitoes. While not as toxic as deltamethrin, the isoxazolines and meta-diamide, broflanilide, represent promising classes of insecticides that could be formulated for use against adult mosquitoes, with the advantages of a favorable mammalian toxicological profile and no cross-resistance in pyrethroid resistant strains.

Mosquito control programs deploy mosquito traps for surveillance and targeting of vector mosquitoes. The primary attractant in these traps is generally carbon dioxide (CO2), which acts as a powerful long-distance lure. Historically, dry ice and compressed gas have been accessible as lures, but they may exhibit logistical hardships (storage, safety, equipment, calibration, consistency, etc.). Additionally, the aforementioned standards can be inaccessible in remote or low-resource environments. Microbial lures have often been proposed to bridge this gap, but prior options, such as yeast, have proven inferior compared to traditional CO2 lures. However, a mycelium-based CO2 generator, the Exhale CO2 Bag, is now commercially available. Initial studies suggested this product may be suitable for mosquito surveillance. To validate this, semi-field cage assays were conducted in Florida by releasing several species of vector mosquito into enclosures to be recollected by either Biogents or United States Centers for Disease Control and Prevention (CDC)-style traps paired with the Exhale, gas cylinders, dry ice, or unbaited. Dry ice and compressed gas performed equivalently, with Exhale collecting 25% to 50% fewer mosquitoes, and unbaited traps collected 10% to 30% fewer than Exhale. Additionally, field testing in Utah, with traps deployed across rural wetlands, industrial transition areas, and urban metropolitan areas, all yielded the same result: the Exhale mycelium and unbaited traps collected an average of 35 or fewer mosquitoes, as compared to regulated gas CO2 traps collecting 1,000 to 3,000 mosquitoes in the same areas. Though some merits exist for a mycelium-based trap, the current data and recent literature fail to support this technology for host-seeking traps in existing mosquito surveillance programs.

West Nile virus (WNV) is a mosquito-borne flavivirus endemic to the United States. Several regions, including parts of the Midwest, experience sustained WNV transmission with annual local and regional outbreaks. In the upper Midwest, Culex pipiens Linnaeus and Culex restuans Theobold, play key roles in WNV circulation, with Cx. pipiens considered the primary epidemic vector responsible for human cases and Cx. restuans linked to early-season enzootic amplification. These species share ecological niches, have similar host preferences, and are morphologically difficult to distinguish. Both are implicated in WNV transmission, but species-level differentiation is not routinely prioritized for many surveillance and control programs due to logistical challenges and limited evidence to support the effort. This narrative review investigates the role of Cx. restuans in WNV transmission in the upper Midwest, focusing on distribution, morphology, vector competence, population dynamics, and vector control. We synthesize current evidence and identify knowledge gaps that may inform vector surveillance practices and contribute to more targeted WNV control strategies.

Statistical modeling of infectious disease transmission patterns has been in existence since the mid-1700s, evolving in their utility as the scientific and technological revolutions progressed. Despite the expansion of emerging mathematical and statistical methodologies over the past 250 yr, their usage has largely remained restricted to academic settings. This forum article will discuss the evolution of disease modeling techniques, the most common types of models in use today, and recommendations on how key archetypes can be incorporated into future public health practice. With the recent global impetus to predict and forecast novel pathogens, this article raises the question: Why are endemic arboviruses not included in public health modeling efforts, and how can medical entomologists promote their inclusion?

Tick-borne diseases are among the most widespread vector-borne infections, including zoonoses caused by bacterial and protozoal microorganisms. This study consisted of a serosurvey for Rickettsia spp. in 270 horses from 11 farms in the coastal region of Pernambuco, Brazil. Through the indirect immunofluorescence assay (IFA) based on antigens of five Rickettsia species, 164 (60.7%) horses were seroreactive to Rickettsia spp., with seroreactivity among farms ranging from 10 to 100%. Through molecular analysis, all 270 horse blood DNA samples tested negative by PCR assays targeting Anaplasmataceae family or genus Borrelia agents. A total of 1,852 ticks was collected from horses and identified as 1,850 Dermacentor nitens Neuman, 1897, and two Rhipicephalus microplus (Canestrini, 1888). No rickettsial DNA was amplified from horse ticks. Additionally, 48 tick specimens were collected from 14 wild vertebrates from the same study region, and identified into six species: Amblyomma fuscum Neumann, 1907, Amblyomma longirostre (Koch, 1844), Amblyomma nodosum Neumann, 1899, Amblyomma rotundatum Koch, 1844, Amblyomma varium Koch, 1844, and Ornithodoros mimon Kohls, Clifford & Jones, 1969. Twenty-five of these ticks were processed by molecular analysis, which resulted in no amplification of DNA from Anaplasmataceae, Piroplasmida, Borrelia, or Coxiella. However, three adults of A. nodosum contained DNA of Rickettsia parkeri Lackman et al., 1965 strain NOD, and two larvae of A. longirostre contained DNA of Rickettsia amblyommatis Karpathy et al. (2016). This study provides serological evidence of exposure to spotted fever group (SFG) rickettsiae in horses and reports two SFG agents infecting ticks from wildlife in Northeastern Brazil.

Anopheles farauti (Laveran, 1902) is a major malaria vector in the Southwest Pacific region that is showing behavioural resistance to indoor insecticide-based vector control. This study utilised fluorescent dust-based mark release recapture (MRR) experiments to quantify the dispersal characteristics of An. farauti through a non-village natural ecosystem in tropical north Queensland, Australia. Good quality adult mosquitoes were collected from the field using a Fan Box Traps (FBT), with initial parity dissections of this material showing a daily survival rate of 0.68 during the wet season and 0.75 during the dry season. We then performed 51 separate mosquito MRR releases (19,889 marked An. farauti) during the wet and dry seasons between 2015 and 2017. Mosquito recaptures utilised three collection systems: human landing catches (HLC), FBTs and a bespoke mosquito catch barrier system (MCB). Most of the 308 (1.55%) marked An. farauti were recaptured by the MCB (78%), while the rest (22%) were recaptured by either our CO2 baited FBT and HLC. The longest flight distance was 3.51 km and An. farauti was estimated to travel approximately 73 m per day with HLCs collecting approximately 14 times more mosquitoes than the CO2 baited FBT. This data provides novel insights into the movement and survival of An. farauti in a natural ecosystem, suggesting longer flight distances than documented and different survival rates between the wet and dry seasons. These parameters will be important for modelling pathogen transmission dynamics, potential mosquito gene drive spread, and contribute to future malaria control strategies in the Southwest Pacific.

Rhipicephalus sanguineus (Latreille) is a species complex of ticks that are important vectors of many diseases to humans and other animals. In Arizona, the ranges of the 2 primary genetic variants-the temperate and the tropical lineages-overlap. The temperate and tropical lineages of R. sanguineus s.l. have divergent strains of the obligate Coxiella-like endosymbiont; however, it is unknown whether the microbiomes of the temperate and tropical lineages are otherwise different. There is growing evidence that non-pathogenic bacteria may be important components of vector-borne disease dynamics, even at low abundance. This research utilized a blocking primer to prevent sequencing of Coxiella to enable a closer examination of bacterial community structure of R. sanguineus s.l. ticks in Arizona. There were many commonalities among bacterial genera found within R. sanguineus s.l. ticks across the state, but no clear distinctions in bacterial community composition based on lineage, sex, female engorgement level, or collection location. Keywords: acarology, insect-symbiont interaction, microbiology, medical entomology.

Culicoides Latreille biting midges are best known for their blood-feeding behaviors and pathogen transmission. However, biting midges also feed on sugar resources for energy, an area of study that has received little attention. In this study, we examined the impact of supplementing blood feeding with access to either water or sugar (10% sucrose) on midge fecundity, fertility, and progeny development. Culicoides sonorensis Wirth & Jones were provided either sucrose or water prior to a blood meal and subsequently either sucrose or water after the blood meal, resulting in 4 treatments. Individual females and F1 progeny were tracked to investigate metrics associated with reproductive and progeny success. Access to sucrose prior to a blood meal increased adult survival and resulted in a 12.9% increase in the proportion of females successfully taking a blood meal. Females provided access to sucrose after a blood meal produced eggs 2.1 d later than females provided water only after a blood meal. Significant results were found for proportion of egg hatch, juvenile period length, and F1 female wing length, but results were variable by trial. Availability of natural sugar sources in midge habitats could impact several variables used to calculate the vectorial capacity of biting midges, including survival, blood feeding rate, and vector density. This study emphasizes the need to incorporate sugar ecology into our understanding of vector-borne disease epidemiology. These results also suggest there is potential for using attractive toxic sugar baits as an effective means of control for this vector genus.