Journal of medical entomology最新文献

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.

Insecticide resistance in Aedes aegypti (Linn., 1762) and Aedes albopictus (Skuse, 1894) has hindered efforts to control dengue outbreaks. Understanding resistance profiles and underlying mechanisms is essential to guide the selection of insecticides and synergists for operational use in northern and southern Taiwan. In this study, we conducted WHO-standard insecticide susceptibility assays, synergist-insecticide bioassays, and molecular diagnostics on field-collected Aedes populations to characterize resistance phenotypes and elucidate their mechanisms. Three pyrethroid insecticides: deltamethrin, permethrin, and lambda-cyhalothrin, and two non-pyrethroids: pirimiphos-methyl (organophosphate) and bendiocarb (carbamate), were tested. Aedes aegypti exhibited resistance to all three pyrethroids and pirimiphos-methyl. High frequencies of multiple simultaneous kdr mutations (S989P, V1016G, F1534C, and D1763Y), along with cytochrome P450 monooxygenase, significantly conferred the pyrethroid resistance in Ae. aegypti. All northern Ae. albopictus populations showed resistance to pyrethroids, although susceptibility to pirimiphos-methyl and bendiocarb varied among populations. The I1532V mutation was detected at low frequency and was not associated with pyrethroid resistance in these populations. Piperonyl butoxide (PBO) restored susceptibility in most Ae. albopictus populations, indicating a significant role of cytochrome P450 monooxygenases in conferring pyrethroid resistance. Furthermore, a significant correlation was found between the frequency of insecticide applications in local areas and reduced mosquito mortality, suggesting that chemical control practices exert selective pressure on Ae. albopictus -populations. This study reveals substantial variation in both resistance phenotypes and mechanisms between Ae. aegypti and Ae. albopictus in Taiwan. These findings underscore the need for adaptive vector control strategies to mitigate resistance development and sustain the efficacy of chemical interventions.

Mosquito control interventions are constrained by the limited availability of active ingredients. While there are already very few, the development of pesticide resistance further constrains the options. Innovation in biorational active ingredients is therefore critical for managing invasive vector mosquito species such as Aedes aegypti (L.) and Ae. albopictus (Skuse). Laboratory and semifield evaluations were conducted to compare the effectiveness and efficacy of the novel compounds S-methobutene with S-methoprene against these species. Laboratory bioassays showed that technical grade S-methobutene was 5.7- to 11.5-fold more active than S-methoprene against Ae. aegypti, and 7.5- to 12.7-fold more active against Ae. albopictus. When compared at equivalent active ingredient levels, S-methobutene granules exhibited 5.7- to 10.2-fold greater activity against Ae. aegypti and 5.8- to 12.3-fold greater activity against Ae. albopictus than S-methoprene granules. In semifield microcosm trials, 1.0% S-methobutene granules achieved efficacy comparable to that of 4.25% S-methoprene granules at the same application rates, confirming the superior performance of S-methobutene at lower concentrations as observed in the laboratory assays. Enhanced bioactivity of the technical grades in laboratory bioassays and the field efficacy of the granular formulations in microcosm tests demonstrated that the novel S-methobutene outperformed S-methoprene against mosquito species Ae. aegypti and Ae. albopictus.