Journal of medical entomology最新文献

Blowfly species, which play a crucial role in forensic investigations as primary colonizers of cadavers, are influenced by environmental factors. However, most research conducted on blowfly species in South Korea remains limited to a single province. We investigated the spatiotemporal distribution of forensically relevant blowflies (Diptera: Calliphoridae) in the southern provinces of South Korea to enhance forensic entomology databases and improve postmortem interval (PMI) estimation. Overall, 3,934 adult blowflies representing 14 species across 5 genera were collected from 4 regions (Changnyeong, Pohang, Yeosu, and Jeju) over a 1-yr period using baited traps. The dominant species included Chrysomya megacephala (Fabricius), Lucilia illustris (Meigen), Lucilia caesar (Linnaeus), and Lucilia sericata (Meigen); Ch. megacephala exhibited a significantly higher abundance in Jeju than in the other regions, particularly during the warmer seasons. A self-organizing map (SOM) and principal component analysis (PCA) were employed to visualize and validate the spatiotemporal clustering of blowfly populations, confirming that seasonal factors strongly influence distribution patterns. The combination of SOM and PCA effectively distinguished seasonal and regional clustering patterns, demonstrating the influence of environmental factors on species-specific distributions. These findings emphasize the importance of considering regional and seasonal variations in forensic casework and the need to expand entomological databases to reflect geographic differences. Furthermore, the observed regional differences in species dominance underscore the need to incorporate environmental variability into forensic models to improve the accuracy of PMI estimates. This study provides fundamental data for improving forensic applications based on insect evidence, particularly PMI estimation and crime scene reconstruction.

The increased prevalence of ticks and tick-borne diseases, combined with health concerns about synthetic repellents, has prompted research into natural alternatives. Products applied to fabric have become more popular, and currently, permethrin is the only active ingredient used in fabric-applied repellents, although consumer use is restricted in Canada. We evaluated the repellency of Citriodiol (lemon eucalyptus essential oil) alone and delivered in a novel fabric spray formulation (AtlanTick Fabric Spray) against Ixodes scapularis and Dermacentor variabilis ticks. Citriodiol oil exhibited overall repellency against I. scapularis nymphs across all concentrations, and none differed significantly from DEET 25% (v/v). In horizontal assays, Citriodiol at 10% v/v (chronic assay) repelled more than 90% of nymphs up to 4 h. When delivered in a fabric spray formulation, it was more effective at repelling ticks overall. In the Y-tube assays, square assays, and human trials, the AtlanTick Fabric Spray applied on different fabric types repelled female adults of both tick species. Repellency reached 100% in square arena trials for up to 3 d post-treatment (cotton) and remained above 70% at 2 wk against I. scapularis across all fabric types. In human trials, repellency remained above 95% for up to 1 wk post-treatment for I. scapularis. For D. variabilis, repellency remained above 95% on all fabric types for 3 d post-treatment but declined after 7 d on synthetic fabrics. The new fabric spray offers an innovative alternative to permethrin-based fabric spray products for repelling ticks and reducing the spread of tick-borne diseases.

Aedes aegypti (Linnaeus, 1762) mosquitoes are the primary vectors of several arboviruses of major public health importance, including dengue virus, Zika virus, chikungunya virus, and yellow fever virus. In Haiti, Ae. aegypti mosquitoes are highly abundant and linked to the transmission and spread of these pathogens. As the use of pesticides for control of mosquitoes increases, there is heightened selection pressure for insecticide-resistant (IR) mosquitoes, mitigating the efficacy of pesticides and leading to an increased risk of continual pathogen transmission. To this end, active surveillance of resistance status can inform more effective operational control strategies. In this study, we screened 421 individual Ae. aegypti mosquitoes collected from the Ouest department of Haiti between 2018 and 2019 for the presence of IR mutations S989P, F1534C, V1016I, and V1016G. We observed IR-conferring alleles in all study sites, including a high prevalence of the homozygous resistance variant of F1534C across time, an increased prevalence of the homozygous resistance variant V1016I across time (an estimated 12.27% higher odds across time), and the absence of resistance-associated alleles for S989P. Our results indicate that pyrethroid resistance is prevalent and increasing in Ae. aegypti populations within this region of Haiti.

Aedes aegypti (Linnaeus) are rapidly spreading across the globe. Evidence suggests that a Type I hypersensitivity reaction, characterized by IgE-mediated mast cell degranulation, may enhance the blood-feeding behavior of Ae. aegypti. Chymases, the mast cell-specific proteases, may play a critical role in this process. To investigate the role of mouse chymase mast cell protease-4 (mMCP-4) on mosquito blood feeding, we incubated bone marrow-derived mast cells with serum from mice sensitized by female Ae. aegypti bites and subsequently challenged the cells with salivary gland proteins (SGPs) from female mosquito. And the degradation of SGPs by mMCP-4 was assessed. Then, the MCP-4 deficient mice were sensitized twice by Ae. aegypti, the first bite on day 0 and the second on day 3. Throughout these experiments, we recorded the total blood meal duration, probing time, and blood feeding of the mosquitoes and analyzed the cutaneous microbiota. We discovered that serum from sensitized mice enhanced mast cell degranulation and chymase release. And mMCP-4 degraded some SGPs, in particular, potentially cleaving the blood-feeding-related salivary protein D7. Mcpt-4 deficiency resulted in prolonged blood-feeding duration during the second exposure, without affecting initial probing behavior. Moreover, Mcpt-4-deficient mice exhibited a reduced proportion of mosquitoes achieving rapid engorgement. Skin microbiome profiling revealed that Mcpt-4 deficiency attenuated the bite-induced expansion of potentially harmful bacterial taxa, including the dominant genus Corynebacterium (Mycobacteriales: Corynebacteriaceae). These findings identify mMCP-4 as a critical mediator of mosquito blood-feeding behavior and a modulator of skin microbial ecology in response to Ae. aegypti bites.

Anopheles mosquitoes spread malaria, which is caused by Plasmodium parasite infection. In nature, both male and female mosquitoes typically ingest sugars from floral nectar; however, few studies have investigated the effects of sugars as an insecticide for mosquitoes. During our previous work, the lifespan of An. stephensi was shortened by the feeding of high concentrations of lactose. The mechanism by which lactose can shorten the lifespan of mosquitoes is still unidentified. The present study aims to evaluate the potential of lactose as an insecticide against mosquitoes. A sublethal concentration of lactose decreased the lifespan of An. stephensi but did not affect their blood-feeding ratio or the number of eggs they laid. Female Anopheles mosquitoes refused to ingest lactose-containing sugars when a lactose-free sugar is available; however, male mosquitoes ingest them. Both sexes excreted lactose from their bodies after feeding, while other sugars were completely absorbed and digested. An ingestion volume assay using food dye revealed that lactose reduces the volume of the solution in the mosquito body. Female mosquitoes forced to ingest lactose for 3 wk showed a slight change in the composition of their midgut microbiota but not in their relative quantity. These findings suggest that lactose feeding causes osmotic diarrhea-like symptoms in Anopheles mosquitoes. The use of attractive toxic sugar baits with lactose as an insecticide is expected to control male Anopheles mosquitoes.

The eastern gray squirrel (Sciurus carolinensis Gmelin) is a widely distributed rodent in North America, including introduced populations in western regions. Despite being widespread in urban and suburban ecosystems, their role as reservoirs for tick-borne pathogens has been understudied compared to other wildlife hosts. This study investigates the prevalence of ectoparasites and tick-borne pathogens in eastern gray squirrels across suburban habitats in Centre County, Pennsylvania, United States. Over 2 yr, squirrels were trapped across 5 sites and examined for ectoparasites. Ticks were the most common ectoparasites identified, followed by lice, fleas, and mites (in order of prevalence). Ixodes scapularis Say was the only tick species identified. The head, particularly the ears, was the most frequently infested body region. In addition to ectoparasite surveillance, we assessed the presence of tick-borne pathogens in squirrels and pathogens in ticks. Squirrels were RNA-positive for Borrelia burgdorferi ([Johnson, Schmid, Hyde, Steigerwalt & Brenner]), Anaplasma phagocytophilum (Foggie, 1949), Borrelia miyamotoi (Franca, 1910) Fukunaga, Babesia microti, and Rickettsia rickettsii (Wolbach, 1919). ELISA screened 61 serum samples collected from individual squirrels for antibodies to the Borrelia burgdorferi VlsE and Anaplasma P44 proteins. Sixty-two and 17% were positive for antibodies to VlsE and P44, respectively, indicating past or current infection. The data presented collectively contribute to our better understanding of pathogen exposure in eastern gray squirrels. The results highlight the potential role of the eastern gray squirrel in vector ecology and the epidemiology of tick-borne diseases. Enhanced surveillance efforts in peridomestic areas are warranted and may mitigate zoonotic risks to humans and domestic animals.

Blow flies (Diptera: Calliphoridae) are crucial in forensic investigations due to their association with both living and dead humans and other animals. Additionally, their interactions with various resources and potential as vectors of pathogens of humans and other animals, thus, make them potential tools for biosurveillance. This study investigated the potential of monitoring volatile organic compounds (VOCs) emitted by blow flies exposed to Salmonella as a method for pathogen surveillance. Adult blow flies (Cochliomyia macellaria) were exposed, or not, to Salmonella enterica. Following exposure, VOCs released by the blow flies were collected and analyzed using gas chromatography-mass spectrometry (GC-MS). Results indicate a treatment by time interaction (P < 0.01). Indicator species analysis identified a single compound significantly associated with S. enterica exposure (P = 0.02), Nonane, 2,2,4,4,6,8,8-heptamethyl, potentially indicating an immune system response. Given a compound indicating exposure was detected, future research should determine if more replicates could detect more differences after Salmonella ingestion. This research highlights the potential of blow flies as biosurveillance tools and the potential value of volatiles for assessing their exposure to pathogens.

Amblyomma kappa Kwak, 2024 (Acari: Ixodidae) is synonymized with Amblyomma formosanum Schulze, 1933. Availability of the name A. formosanum is justified, and a morphological comparison is presented.

CRISPR/Cas systems have the potential to revolutionize DNA detection of vector-borne pathogens with highly specific and user-friendly assays. One such system, named DNA Endonuclease Targeted CRISPR Trans Reporter (DETECTR), uses a guide RNA (gRNA) and Cas enzyme to bind to and cut DNA targets. Following cutting, Cas12a exhibits non-specific collateral cleavage of single-stranded DNA (ssDNA). A ssDNA reporter in the reaction allows the trans-cleavage activity to be harnessed as an amplified output signal upon recognition of the target by the Cas12a/gRNA complex. We developed a DETECTR assay to detect Borrelia burgdorferi sensu stricto, the primary Lyme disease pathogen in the United States, in blacklegged ticks (Ixodes scapularis) collected from forests in southern Vermont. We compared DETECTR to gel electrophoresis of PCR-amplified products and used quantitative real-time PCR (qPCR) of a different B. burgdorferi primer set for independent confirmation. We found that 123/125 of the samples had identical results for DETECTR and gel electrophoresis. Both assays identified the same 33 B. burgdorferi-positive samples and the same 90 B. burgdorferi-negative samples. On a subset of eight samples, we tested DETECTR using lateral flow test strips and obtained identical results to those obtained with the fluorescence-based DETECTR. The sensitivity of DETECTR was lower than qPCR, which detected nine additional B. burgdorferi-positive samples. When qPCR is not available, the DETECTR assay offers a robust alternative to gel electrophoresis that is more user-friendly and requires less time. Due to the highly specific nature of the assay, DETECTR provides additional confidence that a B. burgdorferi target is present.