Because the vertical distribution and diversity of blood-sucking flies are poorly known, we determined the diversity, structure, and composition of culicids between vertical vegetation strata. We evaluated the influence of microclimatic variables during different times of the day over a year. We used eight CDC traps baited with CO₂ at a height of 1.5 m and 12-15 m. We conducted rank-abundance curves, similarity analysis (ANOSIM and SIMPER), and multivariate clustering with incidence and abundance data. We used GAM models to analyze the influence of strata (understory vs canopy), humidity, and temperature on insect richness and abundance. During the day, the difference between strata was mainly due to higher abundance of Wyeomyia arthrostigma and Wyeomyia ca. adelpha in the understory. During the night, the differences were mainly due to higher abundance of Culex stigmatosoma, Culex salinarius, and Aedes allotecnon in the canopy, and Wyeomyia arthrostigma in the understory. Seasonality played a role in the similarity between the strata. Diversity during the day was positively related to humidity and temperature, and nocturnal diversity increased with temperature but decreased with higher humidity. The effects of environmental factors on the spatiotemporal distribution of fly species are essential for epidemiological surveillance.

Amazonian savannas are among the most noteworthy landscape components of the coastal plain of French Guiana. Although they cover only 0.22% of the territory, they bring together a large part of the animal and plant diversity of this overseas region of France. This article outlines the results of the first study dedicated to mosquitoes (Diptera: Culicidae) of Amazonian savannas. Samplings were conducted in eight independent savannas evenly distributed along a transect of 170 km on the coastal plain of French Guiana. A total of 50 mosquito species were recorded, which is about 20% of the culicid fauna currently known in French Guiana. Among them, Culex (Melanoconion) organaboensis sp. nov. and Cx. (Mel.) zabanicus sp. nov. are newly described based on both morphological features of the male genitalia and a DNA barcode obtained from type specimens. Diagnostic characters to assist their identification are provided and their placement within the infrasubgeneric classification of the subgenus Melanoconion is discussed.

Based on historical and recent records, an updated list of 244 nominal species and three undescribed mosquitoes from Mexico is presented. Since 1990, 15 species have been recorded for the first time in Mexico: Aedes guatemala, Ae. brelandi, Ae. insolitus, Ae. melanimon, Ae. albopictus, Culex daumastocampa, Cx. metempsytus, Cx. erethyzonfer, Culiseta melanura, Limatus asulleptus, Sabethes gymnothorax, Trichoprosopon pallidiventer, Toxorhynchites moctezuma, Uranotaenia socialis, and Wyeomyia chalcocephala. Five species were discovered and described: Ae. amaterui, Ae. lewnielseni, Cx. diamphidius, Shannoniana huasteca, and Tr. mixtli. Three species were discovered without yet describing or naming them: Ae. (Protomacleaya) sp. 1, Ae. (Ochlerotatus) sp. 2, and Wyeomyia sp. 3. Five species had been removed from the Mexican mosquito fauna: Ae. stigmaticus, Cx. imitator, Onirion personatum, Sa. tarsopus, and Tx. theobaldi. With the intention of updating the checklist of the mosquito species in Mexico, historical and recent species records were reviewed, as well as the review of entomological collections, resulting in the confirmation of the presence in Mexico of Ae. thelcter, Cs. impatiens, and Orthopodomyia alba. Morphological and molecular evidence confirms the presence of Wy. jocosa, while Anopheles atropos, Psorophora confinnis, Cx. jenningsi, Mansonia indubitans, Tr. pallidiventer, and Tr. soaresi are removed from the Mexican mosquito fauna.

In the United States, there has been a steady increase in diagnosed cases of tick-borne diseases in people, most notably Lyme disease. The pathogen that causes Lyme disease, Borrelia burgdorferi, is transmitted by the blacklegged tick (Ixodes scapularis). Several small mammals are considered key reservoirs of this pathogen and are frequently-used hosts by blacklegged ticks. However, limited studies have evaluated between-species host use by ticks. This study compared I. scapularis burdens and tick-associated pathogen presence in wild-caught Clethrionomys gapperi (southern red-backed voles) and Peromyscus spp. (white-footed mice) in forested areas where the habitat of both species overlapped. Rodent trapping data collected over two summers showed a significant difference in the average tick burden between species. Adult Peromyscus spp. had an overall mean of 4.03 ticks per capture, while adult C. gapperi had a mean of 0.47 ticks per capture. There was a significant association between B. burgdorferi infection and host species with more Peromyscus spp. positive samples than C. gapperi (65.8% and 10.2%, respectively). This work confirms significant differences in tick-host use and pathogen presence between sympatric rodent species. It is critical to understand tick-host interactions and tick distributions to develop effective and efficient tick control methods.

Aedes aegypti is the species of greatest concern for mosquito-borne disease in the Florida Keys. Previous locally transmitted dengue outbreaks in Key West (2009-2010) and Key Largo (2020) illustrate the need for an immediate and effective response plan to maintain Ae. aegypti populations below threshold levels. An important part of the Florida Keys Mosquito Control District's vector response plan is adulticide application because it can provide an immediate reduction in Ae. aegypti adults in the community. It has become apparent that in the Florida Keys, and throughout Florida, Ae. aegypti resistance to the adulticide permethrin is prevalent. This study uses the CDC bottle bioassay method to look at resistance in Ae. aegypti collected from Key Largo, Vaca Key, and Key West, FL. Resistance was found in all three populations when exposed to permethrin and Sumithrin® but not malathion. Inhibitor testing revealed that esterase and glutathione transferase activity is involved in resistance to permethrin in Key Largo and Key West Ae. aegypti populations while oxidase activity is involved in resistance to permethrin in Ae. aegypti from Vaca Key. Lack of knockdown at the diagnostic time and previous studies detecting the presence of kdr-associated allele mutations suggest knockdown resistance in all three populations. Results from this study show that there are multiple factors involved with resistance in the Ae. aegypti populations in the Florida Keys and that resistance mechanisms vary between islands. Continued surveillance will remain important so the most effective active ingredients can be used in response to future disease transmission.

Sand flies were collected from 55 locations in Jordan covering all governorates during May, 2019–October, 2019. A total of 595 sand fly specimens were collected and were identified. Eight species of genus Phlebotomus: Ph. alexandri, Ph. tobbi, Ph. perfiliewi, Ph. major syriacus, Ph. jacusieli, Ph. papatasi, Ph. sergenti, and Ph. canaaniticus were recorded in this study. DNA barcoding and molecular characterization for collected Phlebotomus sand fly species were performed. Molecular work confirmed the morphological identification. This study shows the presence of low genetic differentiation within Ph. papatasi, Ph. alexandri, and Ph. sergenti populations which could be due to high gene flow, suggesting that gene flow is not restricted by geographic distance or climate for our samples.

Scrub typhus cases are increasing in several regions of Mizoram State, India. However, there is no scientific evidence to support the occurrence of rodent hosts, vectors, or genotypes of Orientia tsutsugamushi from chigger mites in this area. Our goal was to include genotyping O. tsutsugamushi in vector mites and identification of hosts and vectors. Rodents that were caught in forests, paddy fields, and peri-domestic areas were examined for ectoparasites. Morphological and molecular techniques were used to identify rodents and ectoparasites down to the species level. Real-time and conventional polymerase chain reactions using species-specific primers targeting 47 kDa outer membrane protein and 56 kDa type-specific antigen genes were used for the detection and genotyping of O. tsutsugamushi from ectoparasites. A total of 655 rodents comprising 12 species under seven genera were captured from 64 study sites. A total of 16,379 ectoparasites were collected from rodents. Leptotrombidium deliense, Leptotrombidium fletcheri, and Leptotrombidium chiangraiensis collected from Rattus tanezumi and Rattus nitidus were identified as vectors of Orientia tsutsugamushi. Phylogenetic analysis also showed that O. tsutsugamushi detected from vector mites belongs to Karp, Gilliam/Kawasaki, and Kato-related genotypes. The present study documented multiple species of vectors and genotypes of O. tsutsugamushi in rodents, indicating a considerable diversity of vectors and pathogens in Mizoram. Leptotrombidium deliense is the major dominant species of vector mites identified, which can increase the risk of transmission of scrub typhus from rodents to humans in Mizoram State, India.

A species composition analysis of regions of Kazakhstan was carried out by examining the genetic diversity of the blood-feeding mosquito species Anopheles maculipennis complex in the northern and western regions of Kazakhstan. Mosquitoes of the species Anopheles maculipennis complex are of significant interest due to their role as vectors of malaria and other vector-borne diseases. A comprehensive genetic analysis was conducted using molecular markers. It revealed notable genetic variations within mosquito populations in some Kazakhstan regions, shedding light on the potential implications for malaria control efforts and providing valuable insights for future research in the field of vector biology and disease epidemiology.

Pathogens can be influenced by the microbiome of their hosts. Therefore, characterizing the microbiome of hosts, particularly vectors, may help explain pathogen transmission patterns and facilitate the development of novel transmission-blocking approaches. Borrelia burgdorferi is a bacterium that is transmitted by blacklegged ticks (Ixodes scapularis) in the eastern and upper midwestern United States and causes Lyme disease in humans. Borrelia burgdorferi has been hypothesized to be susceptible to exclusion from the midgut of blacklegged ticks by other bacteria, however, blacklegged tick microbiomes have not been characterized across the entire geographic range of the tick. Here we compare the microbiomes of whole nymphal blacklegged ticks infected and uninfected with B. burgdorferi collected at three sites across the state of Delaware that have a high-incidence of Lyme disease. Infected and uninfected ticks did not differ in alpha diversity of their microbiomes and had similar microbiome compositions after removing B. burgdorferi from the analysis. Tick microbiomes varied among sampling locations in terms of both alpha and beta diversity, demonstrating that the tick microbiome can differ over small spatial scales. We also found at least one tick infected with the emerging pathogen B. miyamotoi. Further investigation of blacklegged tick microbiomes throughout their ranges and within specific tick tissues are needed to fully document the effect of microbiomes on B. burgdorferi infection in ticks.

The mating behavior of five species in the mosquito genus Wyeomyia from locations in Panama, Venezuela, and the U.S.A. were video recorded in the laboratory. They represent at least four putative subgenera. There were four objectives: to determine whether they engage in courtship on a substrate, whether genital courtship is involved, how their courtships differ from other courting members of the tribe Sabethini, and how divergent the mating behaviors of these Wyeomyia species are from each other. Their mating behaviors were remarkably similar in most respects. They all mated on either vertical sticks or vertical flat surfaces, the males grasped the costal margin of the wing of the female before inverting beneath her, and the couples passed through a superficial-coupling phase, interpreted as part of genital courtship. The full-copulation phase that followed superficial coupling is presumed to allow insemination, as it does in other sabethine species studied. These Wyeomyia species differed from one another in various positions and movements of the antennae, proboscis, wings, legs, abdomen, and genitalia. Wy. arthrostigma, a species studied previously, is an outlier mainly because of its bizarre mating position. We conclude that these representatives of the genus Wyeomyia have diverged from the Sabethes spp. described so far, but they form a behaviorally coherent group.

Host preference plays an important role in the transmission cycle of mosquito-borne pathogens and can be determined by analyzing the blood meals of mosquitoes. For the present study, 398 blood-fed female mosquitoes collected throughout Germany from 2016 to 2022 were successfully examined for the origin of the blood meal, using two PCR approaches sensitive to various vertebrate groups. The first approach targeted a conserved 16S rDNA region of the cytochrome c oxidase subunit 1 gene; the second approach was only carried out if the first produced no result. The study included 27 mosquito taxa from five genera and identified 50 vertebrate species as hosts: 24 bird, 23 mammal (including humans), two reptile, and one amphibian species. Contrary to common assumptions, Culiseta morsitans/fumipennis showed regular feeding on mammals (including humans) despite its described ornithophilic nature. Similarly, Culex pipiens biotype molestus, previously thought to be highly mammalophilic, fed frequently on birds. Data on the hybrids of the Cx. pipiens biotypes confirmed an indiscriminate biting behavior. Culex pipiens biotype pipiens showed a less stringent preference for birds than expected; however, the preference among avian hosts was clearly for European blackbirds (Turdus merula). Overall, the results argue for a host selection directed by availability in addition to innate preference. These results emphasize the need for further investigations into mosquito host preferences in Germany to better understand disease transmission dynamics.

Following detection of West Nile virus in Harris County, TX, pyrethroid-based adulticides are applied to quickly to disrupt mosquito-borne disease transmission. However, populations of its primary vector, Culex quinquefasciatus, are resistant to permethrin-based adulticides in reference to the susceptible Sebring strain (SEB). Previous studies had detected high kdr allele frequencies in Cx. quinquefasciatus from the operational control areas in Harris County, TX. This mutation provides the advantage of overcoming pyrethroid exposure but may result in a fitness cost under low insecticide selection pressure. We considered that the pyrethroid resistance level may decrease during the months of December through April when adulticide applications by Harris County Mosquito and Vector Control Division are rare. We therefore collected Cx. quinquefasciatus from four areas to estimate their resistance ratio to permethrin-based adulticides using vial assays before and after three generations reared under laboratory conditions in the absence of insecticide selection. Our results demonstrated that mosquitoes from these four areas had low to moderate resistance to the permethrin-based adulticide. The PBO synergist ratio indicated that CYP450s contributed to permethrin resistance. RR₅₀s of mosquitoes from A109 before and after three months in an insecticide-free environment were not significantly different, suggesting a low probability of reducing permethrin resistance after three months without exposure to insecticides and partially explaining the current persistence of resistance populations in the field.