Journal of medical entomology最新文献

Tick-borne diseases constitute the predominant vector-borne health threat in North America. Recent observations have noted a significant expansion in the range of the black-legged tick (Ixodes scapularis Say, Acari: Ixodidae), alongside a rise in the incidence of diseases caused by its transmitted pathogens: Borrelia burgdorferi Johnson (Spirochaetales: Spirochaetaceae), Babesia microti Starcovici (Piroplasmida: Babesiidae), and Anaplasma phagocytophilium Zhu (Rickettsiales: Anaplasmataceae), the causative agents of Lyme disease, babesiosis, and anaplasmosis, respectively. Prior research identified environmental features that influence the ecological dynamics of I. scapularis and B. burgdorferi that can be used to predict the distribution and abundance of these organisms, and thus Lyme disease risk. In contrast, there is a paucity of research into the environmental determinants of B. microti and A. phagocytophilium. Here, we use over a decade of surveillance data to model the impact of environmental features on the infection prevalence of these increasingly common human pathogens in ticks across New York State (NYS). Our findings reveal a consistent northward and westward expansion of B. microti in NYS from 2009 to 2019, while the range of A. phagocytophilum varied at fine spatial scales. We constructed biogeographic models using data from over 650 site-year visits and encompassing more than 250 environmental variables to accurately forecast infection prevalence for each pathogen to a future year that was not included in model training. Several environmental features were identified to have divergent effects on the pathogens, revealing potential ecological differences governing their distribution and abundance. These validated biogeographic models have applicability for disease prevention efforts.

Numerous tick species are undergoing significant range expansion in Canada, including several Dermacentor spp Koch (Acari: Ixodidae). With the recent description of Dermacentor similis Lado in the western United States, additional research is required to determine the current range of this species. Five hundred ninety-eight Dermacentor spp. were collected from companion animals in the western Canadian provinces of British Columbia, Alberta, and Saskatchewan. Ticks were morphologically identified to species, followed by PCR and gel electrophoresis of the ITS-2 partial gene target (n = 595). Ninety-seven percent (n = 579/595) generated valid banding patterns. The banding pattern for the majority (74%, n = 206/278) of Dermacentor spp. from southern British Columbia was consistent with D. variabilis (Say), while 26% (n = 72/278) was consistent with D. andersoni Stiles. For samples from Alberta, 38% (n = 3/8) had banding patterns consistent with D. variabilis and 63% (n = 5/8) with D. andersoni. All (n = 293) ticks from Saskatchewan had banding patterns consistent with D. variabilis. After the description of D. similis was published, DNA sequencing of mitochondrial (16S rDNA gene, COI gene) and nuclear (ITS-2) markers was used to confirm the identity of 40 samples. Twenty-seven samples that had banding patterns consistent with D. variabilis from British Columbia were confirmed to be D. similis. One sample from Alberta and five from Saskatchewan were confirmed to be D. variabilis and seven samples from British Columbia were D. andersoni. The ITS-2 amplicons were not useful for differentiating between D. variabilis and D. similis. These results provide evidence of D. similis in western Canada and highlight that sequences of the mitochondrial genes are effective for distinguishing D. andersoni, D. variabilis, and D. similis.

Several methods of mosquito collection are used for the surveillance of the primary La Crosse virus (LACV) vectors, Aedes triseriatus (Say, 1823), Ae. albopictus (Skuse, 1895), and Ae. japonicus (Theobald, 1901). However, little is known about how the choice of collection method may confound inferences made from LACV vector surveillance data. Therefore, the objective of this study was to investigate potential biases in the surveillance of LACV vectors using the Biogents BG-Sentinel 2 (BGS), CDC-Light Trap (CDC-LT), Biogents Gravid Aedes Trap (BG-GAT), and standard oviposition cup (ovicup). The traps were deployed simultaneously at 10 sites in Knovxille, Tennessee, USA for 20 consecutive weeks. Surveillance results differed widely among the traps, demonstrating a strong potential for trap biases in LACV vector surveillance. The BGS and CDC-LT were effective for collecting Ae. albopictus but were not sensitive to the presence of Ae. triseriatus or Ae. japonicus. The ovicup was the best trap for detecting Ae. triseriatus, while the BG-GAT was the only trap that regularly collected Ae. japonicus. Surveillance conducted with the CDC-LT or BGS indicated that Ae. albopictus was dominant at all sites, but the ovicup and BG-GAT suggested a much larger relative abundance of Ae. triseriatus and Ae. japonicus, respectively. Aedes albopictus and Ae. triseriatus collected in the BG-GAT were significantly larger than those collected from the BGS and CDC-LT, indicating that the traps sampled different sub-populations. A multi-method surveillance approach is recommended to reduce potential biases when conducting surveillance of LACV vectors.

Culex quinquefasciatus is an important mosquito vector responsible for the transmission of filarial worms, arthropod-borne viruses like Oropouche, St. Louis encephalitis, and West Nile and protozoans that cause avian malaria. Due to insecticide resistance documented in Cx. quinquefasciatus populations worldwide, integrated vector management programs can benefit from new strategies to control this species. The In2Care Mosquito Station (In2Care station), a commercially available dissemination station containing pyriproxyfen (PPF) and Beauveria bassiana spores, has been shown to be effective against skip-ovipositing Aedes aegypti and Aedes albopictus in previously conducted semifield and field trials. To determine the potential of Cx. quinquefasciatus adult females to autodisseminate PPF and if the In2Care station could be used for Cx. quinquefasciatus control, we assessed its efficacy in a semifield setting against wild Cx. quinquefasciatus. We found that the In2Care station was attractive to gravid Cx. quinquefasciatus females, with a significantly higher percentage of egg rafts laid in the In2Care station compared to alternative ovipots. Adult females successfully autodisseminated PPF from the In2Care station to surrounding ovipots, leading to a significant increase in mosquito emergence inhibition. Additionally, adult Cx. quinquefasciatus exposure to B. bassiana spores significantly reduced mosquito survivorship. These results suggest that the In2Care station may be effective against Cx. quinquefasciatus in addition to Ae. aegypti and Ae. albopictus. Additional field evaluations are needed to assess impacts at the population level.

Host-seeking behavior of Culicoides species was examined from 2018 to 2019 in West Bengal, India, which elucidated diel activity, feeding success, attack rate, biting rate, and preferential landing of adult Culicoides on the cattle. A comparative assessment was done between the light trap and the aspirator. The host-seeking experiment involved a substantial timeframe of 297 h of catch collections over 27 nights. The number of adult Culicoides captured in the light trap was 1.3 times higher than the aspirator collections. The species in light trap catch were Culicoides oxystoma Kieffer Culicoides peregrinus Kieffer, and Culicoides fulvus Sen and Das Gupta (Diptera: Ceratopogonidae). However, only C. oxystoma and C. peregrinus were collected using the aspirator. The findings related to feeding success, attack rate, and biting rate carried significant implications for the vectorial potential of C. oxystoma and C. peregrinus. The light trap data suggest that Culicoides species displayed crepuscular behavior, while the aspirator collections peaked 1 h before sunrise, between 04:00 and 05:00 h, and gradually declined. A separate study evaluated the exophily and endophily of Culicoides in 2016 at Memari in West Bengal. To delve into the indoor-outdoor activity, 264 trap collections were made in 4 combinations: Light trap operated in the presence and absence of cattle, placed outdoors and indoors. The study revealed that the outdoor prevalence of midges was 14 times higher than the indoor. There was a 6-time increase in the prevalence of adult Culicoides in the presence of cattle, indicating a preference for outdoor locations for feeding.

A previous laboratory study using Haemaphysalis longicornis Neumann (Acari: Ixodidae) ticks of North American origin showed that larvae could acquire the Lyme disease spirochete, Borrelia burgdorferi sensu stricto (s.s.) (Spirochaetales: Spirochaetaceae) while feeding to completion on infected mice. However, the infection was lost during the molt to the nymphal stage. Nonetheless, questing H. longicornis nymphs and adults collected by drag sampling in the northeastern United States have been reported infected with B. burgdorferi s.s. DNA; occasionally these ticks appeared to be partially engorged. This raises the question of whether H. longicornis ticks can (i) acquire B. burgdorferi s.s. during an interrupted, partial blood meal on an infected host and (ii) transmit spirochetes while completing the blood meal on a second host. In this laboratory study, we demonstrated that H. longicornis nymphs could acquire B. burgdorferi s.s. from infected Mus musculus mice during a partial blood meal. Borrelia burgdorferi s.s. was detected by a multiplex polymerase chain reaction amplicon sequencing assay in 2 of 32 (6.3%) nymphs allowed to remain attached to infected mice for 48 h but, paradoxically, not in any of 25 nymphs that remained attached to infected mice for 72 h. Unfortunately, due to the low percentage of infected nymphs, we were not able to examine if such partially fed, infected nymphs were able to transmit B. burgdorferi s.s. while completing their blood meal on a second, naïve host.

Geographic ranges of ticks and tick-borne pathogens within North America are shifting due to environmental changes and human-driven activities, with species of public health concern presenting a multifaceted risk to human health. Innovative strategies and continued collaboration to control tick populations are needed to combat this growing threat. We conducted a scoping review of the literature to describe the nature of applied tick control research conducted in North America (Canada, Mexico, and the United States) to date, with the goal of describing key concepts and identifying gaps in this research area. A total of 244 articles met our inclusion criteria and were reviewed for patterns in applied tick control authorship and funding, study location, target species, and control methodology. Most studies (83.6%) were conducted exclusively in the United States and 75% focused on ticks of public health concern, principally Amblyomma americanum (Linnaeus, Acari: Ixodidae), Dermacentor variabilis (Say, Acari: Ixodidae), Ixodes scapularis Say (Acari: Ixodidae), and Rhipicephalus sanguineus (Latreille, Acari: Ixodidae). The majority of funding was provided through US federal agencies, predominantly the Centers for Disease Control and Prevention and the United States Department of Agriculture. Ixodes scapularis was the target of over 50% of identified articles, with the majority of research conducted within 3 states in the Northeast region of the U.S. Only 8.2% of included studies evaluated integrated tick management interventions. We note gaps in tick control research regarding (i) non-Ixodes medically relevant tick species, (ii) endemic range coverage, and (iii) control methodologies evaluated.

Bernard Greenberg was a ground-breaking scientist in the worlds of medical-veterinary and forensic entomology, studying the ability of flies to serve as a vector of human and other vertebrate pathogens. His work also extended beyond these topics, creating key studies on flies and their associated microbial ecology. These efforts led to numerous research publications and two books on flies and their associated microorganisms. Greenberg served a pioneering role in establishing the field of forensic entomology in the USA later in his career, publishing key papers and a book that are highly cited to this day. We present a review of Dr Greenberg's scientific contributions concerning flies and disease, insect/microbe interactions, and insects as forensic indicators.

Iran is a biodiversity hotspot of scorpions with 80 recorded species. Thus, scorpion envenomation is a serious public health problem in the country. Here, we used habitat suitability modeling to assess the spatial distribution of scorpions in Iran. Only 45 species had sufficient georeferenced data. We used bioclimatic variables, soil temperature layers, and 9 modeling algorithms to perform habitat suitability modeling. We employed an ensemble approach to obtain the final models. We calculated the richness map and drew distribution maps for genera with more than 1 species. Also, we assessed the scorpions' species richness inside and outside of national parks. Finally, we created a risk map of encountering a venomous scorpion. The results showed that the highest scorpion richness is in the southern and southwestern parts of Iran, especially in the coastal areas of the Persian Gulf. We observed 3 biodiversity hotspots for scorpions that are located in the south and southwestern, central parts, and eastern parts of Iran. Except for northern parts, there is a possibility of encountering a venomous scorpion in other parts of Iran. The 3 biodiversity hotspots are also the areas with the highest chance of encountering a venomous species. We found that the hotspots are not protected and are located in areas facing land-use changes. Thus, hotspots have the highest human-scorpion conflicts. Our results provide new insight into the distribution of scorpion species in Iran. Conservation actions that ensure both human safety and species richness are essential and can be achieved by halting further land degradation in scorpion habitats and providing easy-to-understand manuals for local people.

The mosquito species Aedes aegypti (Linneaus) is the vector of multiple arboviruses, including dengue, Chikungunya, Zika, and yellow fever. Risk of infections associated with these arboviruses continues to expand as the geographical range of Ae. aegypti extends into temperate regions. Although Ae. aegypti is abundant along the U.S.-Mexico border, the ecology of this mosquito species in this temperate/subtropical desert is not well understood. Our study objective was to estimate the seasonal population density in 2 urban communities: Sparks, El Paso, Texas and Anapra, Ciudad Juárez, Chihuahua, Mexico. Estimates of the population density of adult Ae. aegypti were obtained by month (June to December) and across years (2016 to 2018) using gravid traps. Mosquitoes were collected inside and outside a total of 108 and 101 participating homes in Sparks and Anapra, respectively. We determined multiple environmental and climatic factors influencing annual population trends. Generally, an increase in the abundance of Ae. aegypti was associated with an increase in precipitation, moderate temperatures, and high humidity, while months with temperatures below 4.4°C led to near absence of adults. Across months, we found low densities of Ae. aegypti during June and July, followed by near 100-fold increases in abundance from August to October before rapidly decreasing to near zero in subsequent cold season months. Our study sheds light on population dynamics and response variables at the leading edge of Ae. aegypti range, which require the development of targeted vector control measures for this mosquito species in this and other regions.