Journal of medical entomology最新文献

Kissing bugs are blood-feeding insects capable of transmitting Trypanosoma cruzi, the causative agent of Chagas disease, through their feces. In the United States, eleven species of kissing bugs have been documented, with more than 50% species carrying T. cruzi. Understanding their biology is crucial for assessing disease transmission risk; however, limited information exists on their life history in the U.S. This research focuses on the biological development of two kissing bug species Triatoma rubida (Uhler) and T. gerstaeckeri (Stål). They were collected from four locations in New Mexico and reared under laboratory conditions using an artificial feeding system with defibrinated rabbit blood. Nymphs of both species were grouped by molting date, fed biweekly, and monitored for development. Nymphs of both species required multiple blood meals to molt. However, the majority of first instars successfully molted after a single blood meal (84.29% in T. rubida and 85.71% in T. gerstaeckeri). Pre-feeding intervals ranged from 6.32 to 16.37 days in T. rubida and from 8.65 to 15.32 days in T. gerstaeckeri. The stadium duration of each instar was relatively similar between species, with both completing development. Overall, developmental times were longer than in previous studies using live animals. Feeding factors (such as extended lag times between feeding, etc.) associated with the artificial feeding system likely contributed to the prolonged nymphal development in both species in our study.

Municipalities on the lower Colorado River are seasonally overwhelmed by swarms of the net-spinning caddisfly, Smicridea fasciatella McLachlan. Nuisance caddisflies pose several public health concerns, including asthma, dermatitis, and mental anguish, and the presence of large swarms can negatively impact waterfront recreation and tourism. Here, survey responses from 123 riverfront homes in Bullhead City, Arizona, were used to assess the nuisance status of S. fasciatella and the perceived effectiveness of area-wide abatement strategies. In 2021, 68% of surveys indicated that nuisance caddisfly conditions were uniformly "intolerable" with no significant differences by location, length of residency, or participating recreational activities. Residents identified that S. fasciatella started to become a nuisance between 2015 and 2016, starting in May and ending in November each year. Proximity to swarming adults, disruption of leisure activities, and maintenance associated with sweeping expired caddisflies were among the biggest complaints. Notably, 58% selected "staying inside" as the most effective strategy to avoid direct contact with swarms, and 14% reported asthma-like symptoms from encountering large swarms or sweeping dead, dried adult caddisflies. Riverfront residents supported trout stocking and river flow manipulation as effective measures to reduce S. fasciatella populations. After three years of river flow manipulations, riverfront residents were asked again to describe nuisance caddisfly conditions, and 61% selected "tolerable", signaling improved conditions in 2024. Collectively, these data provide insights into the nuisance status and potential public health risks of S. fasciatella and support continued research of sustainable management efforts to further suppress populations to a tolerable threshold.

One of the world's least-known simuliid faunas was surveyed over a two-year period and evaluated morphologically, chromosomally, and molecularly. The number of species known from Laos increased from 8 to 31 and includes anthropophilic species and vectors of disease agents. The fauna is remarkably similar to that of Thailand; about 94% of the Laotian fauna is shared with Thailand. At the chromosomal level, species in Laos and Thailand are entirely congruent; no cryptic species were discovered. We also established the chromosomal characteristics of Simulium ubonae Thaijarern et al. to distinguish the larvae from those of its isomorphic sister species, S. fenestratum Edwards. Molecular evaluations using the mitochondrial cytochrome c oxidase I gene for 24 of 31 species indicated genetic similarity among Laotian populations and conspecificity with populations in neighboring countries. Despite streams that have suffered intense environmental assaults, the species richness per stream is high, averaging five species per stream, with as many as 11 species at one site at one point in time.

Recluse spiders are arachnids of potential medical significant due to their necrotic venom. However, in areas populated by the brown recluse, Loxosceles reclusa, bites and necrosis are rare. In Florida, USA, public media reports and medical case studies have propagated three misconceptions about recluse spiders: breeding populations are widespread in Florida, USA; recluse spiders readily bite when encountered; and verified recluse spider bites inevitably produce necrotic wounds. Here, in onsite investigations of 220 Florida properties with alleged infestations of recluse spiders reported to the USDA or the Florida Brown Recluse Project, we found breeding populations of the invasive Mediterranean recluse (L. rufescens) at only 19 sites. In experimental bite assays including non-injurious pressure or pinching to jaws, legs, or abdomen, brown recluse and Mediterranean spiders exhibited negligible bite responses (median = 0%). In contrast, wolf spiders exhibited significant defensive bite responses (median = 80%). Lastly, only one verified bite was reported by an adult female, which did not result in necrosis. In conclusion, our field survey and behavioral assays challenge three long-standing myths specific to Florida. Recluse spiders are scarce. Recluse spiders are reluctant to bite. Recluse spiders are unlikely to account for most necrotic skin wounds attributed to them. In the final analysis, the risk to humans has been overstated, warranting a reevaluation of their role in suspected necrotic lesions by the medical community and the public.

Chrysomya megacephala (Fabricius, 1794), also known as the oriental latrine fly, is a synanthropic blow fly of medical importance worldwide. Understanding the flight capacity of C. megacephala adults with different day-ages and genders provides a scientific basis for understanding its distribution and potentially effective control. In this study, we used a flight mill to conduct continuous 24-h tethered-flight experiments using unmated male and female adults of C. megacephala at day-ages 1, 5, 9, 13, 17, 21, 25, 29, and 33 under controlled conditions of 25 °C, relative humidity 40%, and light intensity of 565 lux. The results showed that total flight distance was significantly affected by gender. Females exhibited superior flight capacity compared to males, reaching a peak at day-age 29 with a median total flight distance of 12 km. Additionally, the longest total flight distance of an adult female was also recorded at day-age 29, reaching 35.5 km, suggesting strong dispersal potential of C. megacephala adults. In males, the median total flight distance peaked at day-age 9, reaching 4 km, while the longest individual total flight distance was observed at day-age 5, reaching 18 km. These findings demonstrate significant differences in flight capacity between genders and day-ages, providing a scientific basis for assessing the dispersal risk and developing control strategies for fly-borne pathogens, as well as insights into the reproductive and flight behavioral adaptations of this species.

The In2Care Mosquito Station has shown promise as a method of reducing populations of multiple mosquito species, including Aedes aegypti (L.), under semifield and/or field conditions. However, successful field studies have been conducted primarily in geographically isolated areas, where reinvasion of mosquitoes from nearby areas is minimal or absent. To assess the efficacy of In2Care station deployment within nonisolated urban environments, we conducted long-term, label-rate In2Care deployment within a residential neighborhood (Pleasant Street Historical District) in the urban center of Gainesville, FL. A total of twenty-two surveillance sites were distributed equally between our designated treatment zone and control zone. Following a 4-wk baseline period, on 4 May 2023, a total of 160 In2Care stations were deployed within the 13.35-acre treatment zone. When compared to the control zone, no impact was observed on female Ae. aegypti or mosquito egg abundance within the treatment zone following the deployment of In2Care stations. Additionally, no shift in the parity rates of females were recorded, indicating that together, the presence of In2Care stations did not affect Ae. aegypti abundance or age structure. These results indicate that In2Care deployment at a density of 12 stations/acre may not be effective for reducing mosquitoes in nonisolated settings, where reinvasion from surrounding areas is likely.

Parasites are quite likely the most diverse guild of species on earth. Nevertheless, they remain under-documented despite their impact on the health and ecology of nearly every other species. Natural history collections offer a powerful, underutilized resource for uncovering the hidden diversity of parasites, particularly by preserving specimens that reveal unexpected host-parasite associations. Ticks, although known for their broad host range among terrestrial vertebrates, have never been documented parasitizing fish. Here, the author reports the first known instance of ticks associated with a fish host: 2 female Amblyomma sp. ticks were discovered on an electric eel, Electrophorus varii  de Santana et al. 2019. One specimen was removed and identified as Amblyomma cajennense sensu stricto (Fabricius, 1787). While likely an instance of opportunistic feeding, this collection record nonetheless greatly broadens the known feeding habits and associations between ticks and their hosts. This observation highlights the value of museum collections in revealing rare interactions that challenge established understandings in host-parasite ecology.

Mosquito-borne diseases pose a dire threat to humanity, claiming over 700,000 lives annually. At the local scale, the interplay between several environmental factors influences mosquito biology: temperature, precipitation, and temporal variations profoundly shape mosquito populations, impacting disease transmission dynamics. However, how environmental conditions modulate sugar feeding has been critically understudied. To bridge this knowledge gap, we conducted field captures across distinct ecological settings: urban and forested areas at high and low elevations. We used established mosquito trapping techniques and satellite-derived data to examine environmental parameters and mosquito abundance dynamics. Moreover, we investigated the relationship between mosquito size, sugar consumption, and environmental variables by analyzing wing length, nectar presence, and carbohydrate concentrations. Results showed a higher proportion of sugar-fed mosquitoes in urban habitats, correlated to the presence of ornamental plants on which mosquitoes can feed and associated with Aedes albopictus dominating the mosquito population (81.3% of trapped individuals). In contrast, Culex mosquitoes accounted for 87.2% of the mosquito populations at both high- and low-elevation forested sites. Altogether, our results identify an interplay between environmental and physiological factors with implications for population prediction and, by extension, mosquito control strategies.

Surveillance is crucial for monitoring tick populations and assessing disease risk. We tested the hypothesis that dry ice-baited traps with a downward-facing sticky surface and traditional drag cloths would be equally effective in capturing ticks in Texas, Oklahoma, and Wisconsin. Experiments ran for 69 to 100 d in the spring-summer of 2023 with three, 60-m-long rows of 4 traps each, spaced 20 m apart, perpendicular to 3, 60-m-long dragging transects with traps spaced 10 m on either side. Traps captured 84.2% of a total of 25,596 ticks, and 64.3% after adjusting the data to equalize the number of person-hours expended for each sampling method. For all 3 life stages of lone star ticks, Amblyomma americanum (L.), traps almost always caught the most ticks per person-hour. For larvae and nymphs of blacklegged ticks, Ixodes scapularis (Say), and adult American dog ticks, Dermacentor variabilis (Say), trapping was either superior or similar to dragging. Correlation coefficients comparing numbers caught by trapping and dragging were generally positive for all 3 species. The magnitude of dragging needed to match the total catch in 1 trap ranged from 323 m2 for D. variabilis in Wisconsin to 511 m2 for A. americanum in Oklahoma. Trapping was also more sensitive than dragging at detecting rare tick species and experienced fewer failures to detect the presence of any ticks. These findings suggest that trapping holds promise as an alternative or supplement to current surveillance methods, pending development of a cost-effective commercial trap.

Culicoides biting midges (Diptera: Ceratopogonidae) are important, yet understudied vectors of animal and human pathogens. Many biting midge species reach significantly higher densities at tree canopy height (10-20 m), compared to ground level (1 m), which may compromise the effectiveness of space spray ground adulticiding. Timing adulticide applications to coincide with the hour(s) of greatest midge density at ground level could ameliorate this issue. However, the circadian activity patterns for most vector species remain poorly understood, especially in regard to vertical movement (between ground and canopy). This study investigated the circadian flight patterns and vertical stratification of two vector species (Culicoides insignis Lutz and Culicoides stellifer [Coquillett]) using a novel hourly sampling light trap operated at ground (≈1 m) and canopy (≈11 m) heights from 1700 h to 0800 h on two Florida deer farms. Both C. insignis and C. stellifer exhibited strong vertical stratification, with significantly more midges collected in the canopy than at ground level, up to 7.4-fold and 11.5-fold differences, respectively. Peak flight activity was not crepuscular, but occurred between 0028 h and 0103 h for C. insignis, and between 2240 h and 0234 h for C. stellifer, varying somewhat by location and height. The circadian and vertical activity patterns observed here contrast with assumptions of crepuscular activity in Culicoides spp. This suggests that the current timing of ultra-low volume insecticide applications on deer farms (typically dusk) is not aligned with peak Culicoides activity (2200 h-0200 h), reducing efficacy of control measures. To optimize Culicoides control outcomes, adulticides should be applied when Culicoides activity peaks.