Journal of medical entomology最新文献

A total of 454 unique sites in western Canada were drag sampled for host-seeking Dermacentor species. Dermacentor andersoni Stiles was detected in British Columbia, Alberta, and Saskatchewan, while D. variabilis (Say) was detected in all four provinces. Dermacentor similis (Lado et al.) was collected from two sites in British Columbia. Dermacentor andersoni was detected as far east as -103.53° and as far north as 52.38° at elevations from 500 m to 1,231 m. Dermacentor variabilis was detected as far west as -110.9° and as far north as 54.78° at elevations from 200 to 1,200 m. Logistic regression indicated that prevalence of D. andersoni decreased with latitude, increased in the west, and increased with elevation to 900 m, then, declined. Prevalence of D. variabilis decreased with latitude, increased eastwards, and declined as elevation increased. Relationships with environmental variables were developed and indicated that mean winter temperature (Jan.-Mar.), summer temperature (Jul.-Sept.) and total winter precipitation affected both species. Dermacentor andersoni occurred at sites with mean winter temperatures between -10.4 °C and 1.4 °C, while most D. variabilis occurred at sites with winter temperatures between -15.0 °C and -7.9 °C. Prevalence of both species increased as summer and winter temperatures increased. Prevalence of D. andersoni also declined as total summer precipitation increased, consistent with it being a xerophilic species. Prevalence was also influenced by ecoregion and soil variables. Models had good fit, low bias, and good discrimination. Results will be useful for forecasting distribution and presence of these tick species throughout western Canada.

Culicoides biting midges (Diptera: Ceratopogonidae) and mosquitoes (Diptera: Culicidae) are important vectors of pathogens affecting ruminants. On deer farms, Culicoides species transmit bluetongue virus and epizootic hemorrhagic disease virus, while mosquitoes can cause chronic stress and even exsanguination. We evaluated the effectiveness of the insecticide -InsectGuard (0.5% permethrin), applied as a barrier treatment and pour-on, to reduce mosquito and biting midge landings on deer in Martin County, Florida. Deer simulators baited with carbon dioxide and fitted with sticky cards were used to trap landing insects. A polyethylene fence barrier treated with InsectGuard (1.34 fl oz/m2) and an untreated fence were tested against a no-barrier control. Separately, InsectGuard pour-on (1 fl oz per deer) was compared to an untreated control. The -InsectGuard-treated barrier and pour-on applications reduced landings of three Culicoides species, including Culicoides insignis Lutz, a key bluetongue virus vector, by 175-fold and 7-fold, respectively. The InsectGuard-treated barrier also reduced mosquito landings: Culex spp. (15-fold), and Psorophora spp. (6-fold). While the InsectGuard pour-on caused a dramatic reduction of C. insignis, it had no measurable effect on Culex spp., Psorophora spp., or Culicoides floridensis Beck and appeared to attract Culicoides pusillus Lutz (8-fold increase). Our findings demonstrate that permethrin-treated barriers and pour-on applications can reduce the landing and, therefore, potential infectious bites of mosquitoes and biting midges. These interventions can be incorporated as part of an integrated vector management program for deer farms to enhance control outcomes, in combination with other strategies such as adulticide sprays, habitat management, and vaccination.

Mosquitoes (Culicidae) are the most important vectors of human and animal diseases globally, making them valuable tools for the molecular surveillance of blood-borne pathogens. By screening mosquito populations, we can evaluate local disease prevalence and ascertain which vector species are involved in local transmission cycles. This study presents the first targeted mosquito-based surveillance of blood parasites in Western Australia. Over a 2-year surveillance program in Perth, Western Australia, 3,288 mosquitoes from 12 species across 5 genera were collected and screened in 461 pools. Parasite prevalence and diversity were evaluated using polymerase chain reaction screening of the Haemosporida cytochrome b gene region, and the Dirofilaria 12S rDNA gene region. Haemosporida were detected in 3.9% of mosquito pools, with 72.2% of positives found in Culex species pools. Avian Haemosporida comprised 83.3% of the total detections. Known avian Haemosporida lineages detected included 1 Haemoproteus (H. zosteropis) and 2 Plasmodium (BELL01 and MYNA02). Three novel lineages, Plasmodium CULPER01-03, were identified. Plasmodium falciparum was identified in 2 pools, and no Dirofilaria were detected. These findings indicate that Perth harbors a diverse range of avian Haemosporida, which may be regionally specific, as all lineages detected have only been identified in the Oceania region. The predominance of positive detections in the Culex pipiens species complex supports their role as the primary vectors of avian Plasmodium. This study highlights the utility of mosquito surveillance for monitoring blood-borne parasites and contributes new insight into parasite diversity and vector associations in Australia.

The ability to determine the sex of tick nymphs has the potential to answer questions concerning tick biology and pathogen ecology. A duplex polymerase chain reaction (PCR) that was recently developed for sex determination in adult Ixodes scapularis Say ticks was used to test whether the method could be applied to determine the sex of unfed I. scapularis larvae and nymphs. We found that the duplex PCR could be used to determine the sex of immature ticks and could also be used on small tissue segments from live nymphs.

Vector management of Anopheles mosquitoes in West Africa is challenged by limited data on distribution, species diversity, seasonal abundance, and lack of reporting mechanisms from sentinel sites. To improve the epidemiological risk assessment for Anopheles-vectored diseases, this study investigated the distribution and species composition of Anopheles mosquitoes in 3 ecological zones of Ghana and compared trapping methodologies. Adult Anopheles mosquitoes were collected monthly over 6 trapping sites from 2017 to 2021 using Centers for Disease Control and Prevention light traps with incandescent and ultra-violet (UV) light sources and Biogents Sentinel (BG) traps. A generalized Linear Mixed Model with a negative binomial distribution was used with the trapping method and month of collection as fixed effects, and the year of collection and site as random effects. Out of a total of 20,222 Anopheles mosquitoes collected, the majority were from the Sudan savannah zone (66.1%), while the Forest zone had the lowest count (1.8%). The predominant Anopheles species identified was An. gambiae s.l. (67.83%). There was a significant association between season and An. gambiae s.l. (P < 0.001), with higher numbers in the wet season than in the dry season. Furthermore, An. gambiae s.l. was less likely to be collected using UV-lighted traps compared to the incandescent-lighted traps (GLMM = -1.06, P = 0.0122). The results of this study will inform the development of evidence-based vector management strategies and contribute to the efforts to reduce the burden of vector-borne diseases in Ghana and West Africa.

The study aims to develop a biolarvicide alternative to synthetic insecticides for controlling Aedes aegypti (Linnaeus, 1762), a major vector for dengue, zika virus, and chikungunya viruses. Turmeric Essential oil Pickering emulsion (TEO PE) was developed to combat mosquito populations. Research offers a unique technology to encapsulate TEO PE in hydrogel beads, enhancing its larvicidal activity. The stability of TEO was enhanced using cellulose nanocrsytals (CNCs). Characteristics of CNC, PE, and hydrogel beads were evaluated using Fourier transform infrared spectroscopy (FTIR), zeta potential, Dynamic Light Scattering (DLS), SEM, and X-ray diffraction (XRD). Hydrogel beads showed effective toxicity against A. aegypti larvae in a dose-dependent method, with significant lethal concentration. FTIR analysis confirms cellulose presence in CNC, while Zeta potential and DLS show stable PE with an average particle size of 94.4 nm. Subsequently, SEM, XRD, and UV-Vis spectroscopy were performed to evaluate the crystallinity, encapsulation and release efficacy of beads, respectively. Larvicidal activity of free TEO and TEO PE-based hydrogel beads was evaluated against third instar larvae of A. aegypti. Outcome of this study demonstrated that hydrogel beads exhibit effective larvicidal activity with mortality (P < 0.001) against the larvae with significant lethal concentration (LC) values (LC50 = 227.074 mg/l ± 7.09912, LC90 = 360.257 mg/l ± 14.0808) as compared to pure TEO (LC50 = 22.8349 mg/l ± 2.28709, LC90 = 47.8297 mg/l ± 2.22492). Histo-pathological analysis revealed extensive damage to internal membranes and midgut regions of the larvae. This approach provides enhanced stability, targeted larvicidal activity, controlled release, and a sustainable alternative to synthetic insecticides.

Paracetamol (acetaminophen) is one of the most widely used drugs worldwide. Easy access to paracetamol contributes an increase in both overdose and suicidal use. The present research examined the combined effects of paracetamol (acetaminophen) and temperature on the some growth and developmental parameters of Musca domestica (Linnaeus, 1758) (Diptera: Muscidae). Larvae were reared on diets with different concentrations of paracetamol (LD50, 2 LD50, and 3 LD50) at 3 temperatures, 20 °C, 25 °C, and 30 °C. To date, no data on the specific impact of different paracetamol concentrations on the development and growth of this species are known to have been published. Larval weights and lengths, larval and pupal durations, adult and pupal weights, and larval and pupal mortality were recorded. Our observations indicated that the developmental periods were affected by concentrations and temperature. Developmental periods were prolonged as the concentration of paracetamol increased. The total larval weight significantly differed among temperatures but temperatures did not significantly affect larval length. Larval and pupal survival significantly differed among concentrations and temperatures. The mortality rate of larvae significantly increased with increasing drug concentrations. Pupal and adult weights were significantly different among diets and temperatures. Pupal and adult weights were reduced when the paracetamol concentrations were increased. These findings demonstrate that paracetamol has significant effects on some life history parameters of Musca domestica and have important implications for forensic investigations.

Sylvatic yellow fever virus is transmitted by mosquitoes Haemagogus and Sabethes genera, which predominantly inhabit forested areas but can also be found near human dwellings in rural zones. In Paraguay, outbreaks of the disease were reported between 2007 and 2008, prompting the initiation of systematic sampling starting from those years to monitor the vectors transmitting the yellow fever virus. This study aims to identify the primary vector species and determine their geographic distribution in Paraguay, based on administrative divisions and ecoregions. Sampling was conducted in 17 departments, the capital district of Asunción and in 7 ecoregions in daylight hours using manual aspirators and entomological nets. Sampling was sporadic (2008-2016) and regular, risk-based from 2017. The collected data were georeferenced and processed using QGIS software. A total of 288 observations were documented, with a higher prevalence in the departments of Alto Paraná (26.74%), San Pedro (21.18%), and Caaguazú (12.50%). Sixteen species were identified, 9 of which belong to the genus Sabethes (89.58%) and 3 to the genus Haemagogus (10.42%). In the Western region or Chaco, only Hg. spegazzinii was found, while species of the genus Sabethes predominated in the Eastern region. The results further indicate that the ecoregions of the Atlantic Forest of Alto Paraná and the Cordillera de los Altos show the highest concentration of these vectors. This study represents the first compilation of the geographic distribution of Haemagogus and Sabethes mosquitoes in Paraguay and makes significant contributions to national surveillance by identifying three priority ecoregions for yellow fever monitoring. The information provided is essential for delineating risk areas and strengthening prevention and control strategies for sylvatic yellow fever, particularly in vulnerable zones.

Climate change is reshaping Arctic ecosystems, heightening the risk of vector-borne diseases caused by pathogens such as California serogroup (CSG) viruses, including Jamestown Canyon virus (JCV) and Snowshoe Hare virus (SSHV). Despite their emerging public health threat, data on Arctic mosquito populations and CSG virus prevalence remain limited. To address this gap, we conducted a 3-yr mosquito surveillance program at 8 sites across northern Canada and the United States, engaging local community members in mosquito collection through a standardized protocol using a butterfly net. From 4,038 sampled mosquitoes, we identified 18 species-17 of which were from the genus Aedes Meigen, 1818. We also reported new distribution records for Aedes euedes Howard, Dyar, & Knab, 1913, Aedes implicatus Vockeroth, 1954, and Aedes spencerii (Theobald, 1901). JCV was detected in 10 mosquito species across 7 sites, while SSHV was detected in just one species at a single site. Notably, JCV was found in Ae. euedes, Aedes impiger (Walker, 1948), and Aedes pionips Dyar, 1919 for the first time in North America. JCV was detected in Cambridge Bay, Nunavut, where only 3 Arctic mosquito species were present, none of which are recognized as potential JCV vectors. This finding raises the possibility of undocumented vector species or a previously unrecognized transmission role for Arctic mosquitoes. The broad distribution of JCV across species and locations suggests widespread enzootic transmission, underscoring the need to reassess the potential of Arctic mosquitoes as disease vectors in a rapidly changing climate.

Malaria continues to be a major public health issue in Ghana, contributing significantly to hospital outpatient visits. Vector control remains central to malaria prevention; however, the growing resistance of malaria vectors to insecticides presents a major obstacle to control and elimination efforts. This review examined the evolution of insecticide resistance in Ghana from 2001 to 2024, summarising resistance mechanisms across the country's bioclimatic zones to inform evidence-based vector control strategies aligned with Ghana's malaria elimination goals. A systematic literature search was conducted using PubMed, Google Scholar, and Scopus databases to identify studies on insecticide resistance in major malaria vectors. A total of 41 articles were retrieved, and data were analysed using Microsoft Excel 365 and GraphPad Prism v.9.1.2. Pyrethroids were the most frequently studied insecticides, particularly in the Coastal (48%, n = 17), Forest (37.1%, n = 13), and Sahel (14.3%, n = 5) zones. An increasing trend of pyrethroid resistance in Anopheles gambiae s.l. was observed across all transmission zones, with the vgsc-L995F mutation being the most reported resistance mechanism. Temporal analysis revealed significant differences in resistance levels over time across all zones. Resistance to dual-active ingredients (piperonyl butoxide + pyrethroid) was also detected nationwide. Notably, there are limited studies on An. funestus susceptibility and metabolic resistance driven by copy number polymorphisms or vgsc variants. Given these gaps, the application of genomic surveillance and whole genome sequencing is essential for identifying locally relevant resistance mechanisms to guide future vector control interventions in support of Ghana's malaria elimination efforts.