Journal of medical entomology最新文献

Published studies and records of species of Anopheles that occur in Thailand are reviewed and lists in public databases are revised. ITS2 and COI sequences of specimens from Thailand available in GenBank were analyzed using a phylogenetic method and compared with sequences of species from other countries. Eighty-one species of Anopheles are currently known to occur in Thailand, including the informally recognized An. aconitus species B, An. annularis species A and B, An. jeyporiensis species B, An. tessellatus species A, C, and F, and An. subpictus species C and D. Three new species complexes, the Aconitus, Jeyporiensis, and Karwari Complexes, are recognized.

Forensic entomotoxicology studies require culture media that fulfill the nutritional needs of the relevant forensic species, enabling their proper growth and development from oviposition to maturity, while minimizing biases due to the presence of xenobiotics in tissues. This study aimed to optimize a culture medium for Megaselia scalaris (Diptera: Phoridae) (Loew, 1866) to enhance oviposition by this species. A bioinformatic approach was used to determine whether M. scalaris possesses homologs of the Ir76b receptor that is activated by putrescine and cadaverine and plays a role in food source identification in other species. Supplementing the media with these amines resulted in oviposition comparable to those observed in porcine tissue without adversely affecting the growth and development of other stages of the life cycle. The Ir76b receptor was also identified in Lucilia sericata (Diptera: Calliphoridae) (Meigen, 1826), another species of forensic relevance. Optimized media similarly supported oviposition in L. sericata, suggesting the formulation's broader applicability.

Since its invasion of the United States in the 1980s, Aedes albopictus (Skuse, 1894) has become a major pest and a significant public health threat in the Southeastern United States. Despite its importance, we know little about its population genetics at fine spatial scales that correspond to the level of management units. To remedy this lack of information, we analyzed Ae. albopictus spatial variation in mosquito abundance and genetic structure in an urban-rural landscape over 2 years (2016 and 2018) in Wake County, NC, United States. We used a reduced representation sequencing method to generate between 1,100 and 30,000 single-nucleotide polymorphisms for population genetic analyses. We found spatial variation in both the abundance and genetic diversity, and significant differences in genetic divergence among sites that varied between the 2 years. The year-to-year variation in the population genetic patterns at the within-county scale suggests a dynamic system that requires extensive geographic, temporal, and genomic sampling to resolve.

Triatoma sanguisuga (LeConte, 1855), the eastern bloodsucking conenose, is an epidemiologically significant triatomine vector in the United States in that it is implicated in documented autochthonous human Chagas disease cases in the United States and can be found across a large geographic area. Despite decades of research interest, this species has proven remarkably challenging to maintain in laboratory culture, with consistent developmental arrest occurring prior to the fifth nymphal instar stage when maintained on standard blood-only feeding protocols. Here, we report a successful protocol for maintaining T. sanguisuga through complete development in laboratory culture. Adult specimens were collected from Des Allemands, Louisiana, and maintained under standard laboratory conditions with blood feeding supplemented by Drosophila artificial hemolymph media (AHL). Early nymphal development proceeded through the third instar on blood meals alone, but development consistently stalled at the fourth instar. Following initiation of AHL supplementation, the first successful fourth-to-fifth instar molt was observed approximately 3 wk later, with subsequent emergence of adult insects occurring within 17 wk. The AHL supplement was readily consumed by nymphs when offered ad libitum at room temperature. This development overcomes a significant barrier to T. sanguisuga laboratory culture and provides compelling evidence for complex nutritional requirements in triatomines beyond those met by vertebrate blood alone. Laboratory-reared T. sanguisuga cultures will enable critical research on vector competence, feeding behavior, reproductive biology, and control measures essential for understanding and managing Chagas disease transmission in North America.

Mosquito-borne diseases are a major public health concern, and exploiting the mosquito's reliance on host odors is an effective way to prevent human exposure. We evaluated the attraction of non-blood-fed female Anopheles stephensi Liston, 1901 mosquitoes (Bandar Abbas strain, laboratory population) to four chemical components found in vertebrate host odors (at 5 dilutions) and their blends using an olfactometer in laboratory conditions. When each compound was combined with CO2, three of the four tested compounds showed significant attractancy (P < 0.05) at their optimal dilutions. Hexanoic acid was the most attractive, followed by 3-methyl-1-butanol and L-lactic acid. We created five blends using the most attractive dilutions, and two of these blends significantly attracted mosquitoes in the olfactometer (P < 0.05). The most promising blend contained 3-methyl-1-butanol and hexanoic acid. This blend has potential for use in odor-baited mosquito traps, but further field research is required to evaluate its effectiveness.

The increasing resistance to insecticides, the limited availability of new insecticides for mosquito control, and the emergence of new disease threats have created an urgent need for alternative tools to manage mosquito vector populations. Mosquito parasites may serve as potential sources for these alternatives. This study aimed to investigate the ectoparasites found on both larval and adult mosquitoes to identify natural biocontrol agents that could help reduce the mosquito population. Mosquitoes were collected in 2019 using dipping and mechanical aspiration methods, human-baited bed net trap, animal-baited bed net trap, and BG-Sentinel trap with CO2 gas. All mosquitoes and their ectoparasites were identified using morphological keys. A total of 1,756 adult mosquitoes and 9,789 mosquito larvae were collected from 3 genera: Anopheles, Culiseta, and Culex. Additionally, 125 water mite larvae were collected and identified as Arrenurus. It was found that 5.5% of adult mosquitoes were infested with this mite. There was a weak but statistically significant relationship between the Anophelinae and Culicinae subfamilies and parasitism by water mites at the P = 0.05 level. Additionally, infestation by Vorticella spp. was observed on the head, thorax, abdomen, and siphon of mosquito larvae. This study represents the first research on the parasitism of water mites and Vorticella spp. on mosquitoes in central Iran. Further detailed studies are needed to enhance our understanding of the biology and ecology of these aquatic organisms that parasitize mosquitoes in Iran, as well as to assess their potential role in mosquito control.

Leishmania infantum is one of the etiologic agents of leishmaniases in mammals. In the Americas, numerous sand fly species within the Lutzomyia genus drive Leishmania spp. transmission, such as the species complex Lutzomyia longipalpis sensu lato. It remains unknown if climatic changes could facilitate range expansion of Lu. longipalpis, creating conditions for local transmission in previously non-endemic regions. The objectives of this study were to identify the climatic and environmental variables of importance for Lu. longipalpis, current ecologically suitable area across the Americas, and determine future areas of ecological suitability under 30-year time periods. Occurrence records were obtained from GBIF, WRBU, and literature searches. Historic climate data (1981-2010) and projection data for Shared Socioeconomic Pathway 3-7.0 for time periods 2041-2070, and 2071-2100 were obtained from CHELSA, along with topographic data from EarthEnv. Using MaxEnt species distribution modelling algorithms, data were incorporated to identify areas which currently are or may become suitable for Lu. longipalpis. Ecological variables such as terrain ruggedness index, number of growing degree days at which mean daily air temperature is above >10 °C, Köppen-Geiger climate classification, and mean daily air temperature of the coldest quarter, were identified as drivers of suitability. Current regions of ecological suitability include areas from the southern United States to northern Argentina. Suitability may expand northward and increase within its current range, specifically in parts of Mexico and Brazil. Findings from this study identify climate and environmental variables impacting Lu. longipalpis distribution, and regions of potential range expansion.

Tick-borne diseases cause a high morbidity in the USA with Ixodes scapularis as the main vector, responsible for the majority of tick-borne diseases in the USA. Understanding disease dynamics requires not just human disease surveillance but also surveillance of the ticks themselves. This study collected 355 I. scapularis adults from 16 sites across Minnesota, Wisconsin and Iowa by drag cloths during 2017-2019. Ticks were tested using 16S sequencing and targeted PCR to identify human relevant tick-borne disease agents. We detected 168 Borrelia burgdorferi positive, 2 Borrelia mayonii positive, 33 Anaplasma phagocytophilum Human Active positive, 1 Anaplasma phagocytophilum Variant-1 positive, 14 Ehrlichia muris positive and 5 Borrelia miyamotoi positive ticks. These results add surveillance data on adult I. scapularis adults in the Upper Midwest.

Reliable and consistent blood feeding is crucial for maintaining mosquito colonies in the laboratory and for supporting scientific research, including vector competence studies (i.e., oral inoculation). However, artificial blood feeding systems often require costly equipment (e.g., Hemotek), and the use of live animals as hosts raises ethical concerns, limiting their practicality. In this study, we developed a simple, low-cost blood feeding system consisting of a perforated plastic pouch heated with a disposable hand warmer and evaluated its effectiveness in supporting blood feeding of 3 mosquito species: Culex quinquefasciatus Say, Aedes aegypti L., and Aedes triseriatus Say. Specifically, we compared feeding success between fresh and previously frozen bovine blood across species. Our results showed that lab-reared Cx. quinquefasciatus achieved the highest engorgement rates (up to 95.7%) across all treatments, whereas field-collected Cx. quinquefasciatus failed to feed on any blood source. Aedes aegypti and Ae. triseriatus exhibited significantly higher feeding success on fresh blood compared to previously frozen blood, with 2.1-fold and 9.7-fold increases, respectively. The perforated pouch system supported full engorgement with minimal leakage and did not require electricity or specialized equipment. These results support the utility of this method for colony maintenance of some lab-adapted mosquito species and vector competence experiments, particularly in settings with limited access to vertebrates or other blood-feeding systems.

Blow flies (Diptera: Calliphoridae) arrive to remains and deposit eggs soon after death, making them useful for estimating a minimum postmortem interval. There can be delays in blow fly arrival due to environmental conditions, concealment, or other modifications of the remains. If there is a delay in blow fly arrival, then, the time of colonization and postmortem interval will be different estimates. Field and laboratory studies were conducted to assess how delays in insect accessibility influence blow fly oviposition behavior by allowing small pigs to decompose indoors with insect activity excluded prior to exposing them to blow flies. The aged treatments included were 24-, 48-, 72-, 96-h along with fresh controls. This research assessed oviposition sites, time to oviposition, and number of eggs laid by Phormia regina Meigen in the laboratory. The field component of this research also looked at initial colonizing species of the aged treatments in addition to time to oviposition and oviposition sites. Phormia regina laid the largest number of eggs on the 48-h treatments and had the shortest time to oviposition on the 48- and 72-h treatments. The 48-h treatment also had the greatest number of unique oviposition sites compared to other treatments. The results of this study indicate that P. regina may prefer to colonize aged remains. More research on this topic could clarify how the postmortem interval estimation should be adjusted when there is a delay in insect colonization.