In recent years, human tick-borne disease occurrence has risen in Oklahoma, U.S.A., but year-round data on tick presence in frequently used recreational areas is not widely available. In this study, ticks were collected...In recent years, human tick-borne disease occurrence has risen in Oklahoma, U.S.A., but year-round data on tick presence in frequently used recreational areas is not widely available. In this study, ticks were collected monthly for one year at residential and non-residential sites in a suburban area of Oklahoma County, OK, U.S.A. At each trapping site, dry ice traps were used in both woodland and grassland areas and fabric tick drags were used in grassland areas. Four species were collected from each park: Amblyomma americanum, Amblyomma maculatum, Dermacentor variabilis, and Ixodes scapularis. Prior to this study, A. americanum was the only species with an established population in Oklahoma County. Consistent with this, A. americanum was collected in all months of the year and accounted for over 90% of ticks collected at each site. Based on our tick survey, we report that A. maculatum, D. variabilis, and I. scapularis, which were each collected in numbers greater than six within a single sampling occasion, are now each confirmed as established populations in Oklahoma County.
Yersinia pestis, a bacterial pathogen that causes sylvatic plague, is present in the prairie dogs (Cynomys spp.) of North America. Epizootics of sylvatic plague through transmission in vectors (fleas) commonly completely...Yersinia pestis, a bacterial pathogen that causes sylvatic plague, is present in the prairie dogs (Cynomys spp.) of North America. Epizootics of sylvatic plague through transmission in vectors (fleas) commonly completely extirpate colonies of prairie dogs. Wildlife managers employ a wide variety of insecticidal treatments to suppress plague and conserve prairie dog colonies. I compiled and statistically compared the available literature describing methods of plague control and their relative effectiveness in managing plague outbreaks by using meta-analyses. Natural log response ratios were used to calculate insecticide-induced vector mortality and vaccine-conferred survival increases in prairie dogs in 37 publications. Further, subgroupings were used to explore the most effective of the available vector suppression insecticides and plague suppression vaccines. After accounting for the type of treatment used and the method by which it was applied, I observed plague reduction through use of both insecticides and vaccines. Insecticides resulted in a significant reduction of the abundance of vectors by 91.34% compared to non-treated hosts (p<0.0001). Vaccines improved survival of prairie dog hosts by 4.00% (p<0.0001) compared to control populations. The use of insecticides such as deltamethrin and carbaryl is recommended to stop actively spreading epizootics, and dual antigen oral vaccines to initially suppress outbreaks.
Chagas disease is one of the main vector-borne diseases in Latin America, including Mexico. Understanding the biological parameters of the triatomine species is a crucial first step in estimating the epidemiologic import...Chagas disease is one of the main vector-borne diseases in Latin America, including Mexico. Understanding the biological parameters of the triatomine species is a crucial first step in estimating the epidemiologic importance of each group. The aim of this study was to compare the biological fitness of Meccus pallidipennis (Stål), M. bassolsae (Alejandre, Nogueda, Cortez, Jurberg, Galvão, Carcavallo) (Hemiptera: Reduviidae: Triatominae) and their laboratory hybrids, by estimating six biological parameters in order to increase the knowledge of the potential role of triatomine hybrids in the transmission of Trypanosoma cruzi to reservoir hosts. Biological parameters related to lifespan, number of blood meals to molt, mortality for each instar, percentage of females at the end of the cycle, number of eggs laid, and hatching of eggs in four cohorts of 100 specimens of M. pallidipennis, M. bassolsae, and their laboratory hybrids were evaluated and compared. In four of the six studied parameters (accumulative mortality, the percentage of females, mean number of laid eggs, and egg hatching), the hybrid cohorts had better fitness results than the parental cohorts. The increase in hybrid fitness found in our study could lead to an increase in the epidemiologic risks caused by transmission of T. cruzi to humans.
Mosquito vectors play a crucial role in the distribution of avian Plasmodium parasites worldwide. At northern latitudes, where climate warming is most pronounced, there are questions about possible changes in the abundan...Mosquito vectors play a crucial role in the distribution of avian Plasmodium parasites worldwide. At northern latitudes, where climate warming is most pronounced, there are questions about possible changes in the abundance and distribution of Plasmodium parasites, their vectors, and their impacts to avian hosts. To better understand the transmission of Plasmodium among local birds and to gather baseline data on potential vectors, we sampled a total of 3,909 mosquitoes from three locations in south-central Alaska during the summer of 2016. We screened mosquitoes for the presence of Plasmodium parasites using molecular techniques and estimated Plasmodium infection rates per 1,000 mosquitoes using maximum likelihood methods. We found low estimated infection rates across all mosquitoes (1.28 per 1,000), with significantly higher rates in Culiseta mosquitoes (7.91 per 1,000) than in Aedes mosquitoes (0.57 per 1,000). We detected Plasmodium in a single head/thorax sample of Culiseta, indicating potential for transmission of these parasites by mosquitoes of this genus. Plasmodium parasite DNA isolated from mosquitoes showed a 100% identity match to the BT7 Plasmodium lineage that has been detected in numerous avian species worldwide. Additionally, microscopic analysis of blood smears collected from black-capped chickadees (Poecile atricapillus) at the same locations revealed infection by parasites preliminarily identified as Plasmodium circumflexum. Results from our study provide the first information on Plasmodium infection rates in Alaskan mosquitoes and evidence that Culiseta species may play a role in the transmission and maintenance of Plasmodium parasites in this region.
A novel rotator trap was evaluated to determine the diel activity patterns and physiological state of adult female mosquitoes in St. Augustine, FL, U.S.A. Culex nigripalpus were most active from 19:00-21:00, followed by...A novel rotator trap was evaluated to determine the diel activity patterns and physiological state of adult female mosquitoes in St. Augustine, FL, U.S.A. Culex nigripalpus were most active from 19:00-21:00, followed by 1:00-3:00, based on collections from the novel rotator trap. Furthermore, analysis of the physiological state of female mosquitoes collected by the novel rotator trap suggested that non-parous (nulliparous) host-seeking mosquitoes were more frequently active in the 21:00-23:00 and 09:00-19:00 time frames. Parous host-seeking mosquitoes were more frequently collected from 19:00-21:00 and 1:00-3:00. A low abundance of gravid females was collected by the rotator trap, so analysis of their activity periods was inconclusive. These results indicate that the novel rotated trap could be used to detect the diel activity patterns of adult mosquitoes in mosquito control programs and more testing should be conducted in the future.
Resistance to agricultural pesticides is an important and insufficiently studied concern for pest and disease vector research. We determined the malathion resistance of species in the Anopheles maculipennis mosquito grou...Resistance to agricultural pesticides is an important and insufficiently studied concern for pest and disease vector research. We determined the malathion resistance of species in the Anopheles maculipennis mosquito group in a habitat near Novosibirsk, Russia. Most of the 851 individuals we measured were members of the Anopheles messeae s.l. complex (An. messeae and An. daciae species). The LC value for malathion was 0.052 mg/L for the mixed specimens, and we failed to find any differences between species. The LC value was within the range of values for malathion resistance of Anopheles stephensi and Culex quinquefasciatus. As the main resistance mechanism to organophosphate and carbamate insecticides is a single mononucleotide substitution in the ace-1 gene, we searched for this mutation in An. messeae s.l. and An. beklemishevi by restriction analysis. This mutation was not found in 347 of the specimens. We sequenced the ace-1 gene fragment for 24 specimens from four species of the Anopheles maculipennis group, including An. messeae, An. daciae, An. atroparvus, and An. beklemishevi. These specimens harbored a nucleotide substitution in the triplet where a mutation can lead to insecticide resistance, but this substitution would make it difficult for the resistance to develop. Since the studied specimens belong to branches of the Palearctic portion of the Anopheles maculipennis group, we suspect that all other Palearctic species of this group would have difficulties harboring the ace-1 mutation that would lead to organophosphate and carbamate resistance.
Anopheles darlingi (Diptera: Culicidae) is the most important vector of malaria in South America and has already been found in peri-urban areas that commonly contain toxic nitrogenous compounds, such as ammonia. The adap...Anopheles darlingi (Diptera: Culicidae) is the most important vector of malaria in South America and has already been found in peri-urban areas that commonly contain toxic nitrogenous compounds, such as ammonia. The adaptation of mosquitoes to polluted breeding sites can increase their distribution and affect the dynamics of vector-borne diseases such as malaria. Therefore, the present study investigated the tolerance of larval instars of An. darlingi to ammonia under acute and chronic exposure conditions. Anopheles darlingi larval mortality, development time, and pupal and adult production using larvae of the 1 (L1) and 3 (L3) instar were assessed as both acute and chronic effects of exposure to different concentrations of ammonia. Lethal concentrations (LCs) for L1 larvae were lower than LCs for L3 larvae. In general, higher ammonia concentrations caused an increase in larval mortality, especially in chronically exposed L1 larvae. The larval development time in L1 and L3 was longer with chronic treatment and decreased with increasing concentrations of ammonia. The number of pupae was very low for acutely exposed L1 and L3 larvae. Likewise, the probability of adult production decreased with increasing ammonia concentrations. This is the first report on the tolerance of An. darlingi to pollutants.
The house fly, Musca domestica (L.) (Diptera: Muscidae), and the stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), are two filth flies responsible for significant economic losses in animal production. Although so...The house fly, Musca domestica (L.) (Diptera: Muscidae), and the stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), are two filth flies responsible for significant economic losses in animal production. Although some chemical control products target adults of both species, differences in mouthpart morphology and behavior necessitates distinct modalities for each. For these reasons, larvicides are an attractive means of chemical control. We assessed the potential of the polyol sweeteners erythritol and xylitol as larvicides to the house fly and stable fly. LC values of erythritol against 2 instar larvae were 34.94 mg/g media (house fly) and 22.10 mg/g media (stable fly). For xylitol, LC values were 74.91 mg/g media (house fly) and 41.58 mg/g media (stable fly). When given a choice, neither species showed a preference for ovipositing in media treated with either sweetener at various concentrations or in media without sweetener. Significantly lower development from egg to adult was observed when the 2 instar LC equivalent of each sweetener was present in the media compared to controls. Erythritol and xylitol both have larvicidal qualities, however their effective concentrations would necessitate creative product formulation and deployment methods to control all stages of developing flies.
Chagas disease represents a significant public health problem in Mexico. In the state of Hidalgo, studies on the presence of triatomines are scarce and restricted to a few locations. To determine the risk of transmission...Chagas disease represents a significant public health problem in Mexico. In the state of Hidalgo, studies on the presence of triatomines are scarce and restricted to a few locations. To determine the risk of transmission in the state of Hidalgo and stratify the vector potential, the distribution of Triatominae was surveyed from 2015 to 2016 in collaboration with primary health care services and local communities. A total of 570 specimens was collected in 278 houses in 25 municipalities. The species of Triatominae detected were T. dimidiata with 391 samples, T. mexicana with 159 samples, T. gerstaeckeri with 17 samples, and T. barberi with three samples. The samples were collected in domestic and peridomestic areas. The general index of natural infection was 9.8%. Indices of colonization and crowding were determined for species and municipality and results were variable.
A list of mosquitoes from the Nakai Nam Theun National Protected Area along the Nam Theun, Nam Mon, Nam Noy, and Nam On rivers, Nakai District, Khammuane Province, Lao People's Democratic Republic (Lao PDR) is presented....A list of mosquitoes from the Nakai Nam Theun National Protected Area along the Nam Theun, Nam Mon, Nam Noy, and Nam On rivers, Nakai District, Khammuane Province, Lao People's Democratic Republic (Lao PDR) is presented. Fifty-four mosquito taxa were identified, including 15 new records in the Lao PDR. A fragment of the mtDNA cytochrome c oxidase subunit I (COI) gene, barcode region, was generated for 34 specimens, and together with four specimens already published, it represented 23 species in eight genera. In addition, an updated checklist of 170 mosquito taxa from Lao PDR is provided based on field collections from Khammuane Province, the literature, and specimens deposited in the Smithsonian Institution, National Museum of Natural History (SI-NMNH), Washington, DC, U.S.A. This paper provides additional information about the biodiversity of mosquito fauna in Lao PDR.
To document and update the mosquito species of Tabasco, Mexico, field collection trips were conducted in the two physiographic regions of Tabasco: the coastal plain of the southern gulf and the mountains of Chiapas and G...To document and update the mosquito species of Tabasco, Mexico, field collection trips were conducted in the two physiographic regions of Tabasco: the coastal plain of the southern gulf and the mountains of Chiapas and Guatemala. Mosquitoes were collected as immature and adult stages during the dry and rainy seasons from 2014 through 2015. Additionally, the Reference Collection of Arthropods of Medical Importance (CAIM-InDRE) containing mosquitoes of Tabasco was re-examined. In total, 4,913 specimens were collected and examined, which are divided into seven tribes, 18 genera, 27 subgenera, and 104 species. Of these, one genus (Shannoniana Lane and Cerqueira), two subgenera (Georgecraigius Reinert, Harbach and Kitching, and Carrollia Lutz), and 21 species are new records for the mosquito fauna of Tabasco. Culex metempsytus Dyar is a new record for Mexico and Wyeomyia jocosa (Dyar and Knab) is removed from the Mexican mosquito fauna. Seventeen species historically reported were not found in the field collections conducted here. Taxonomic notes, new distribution limits, and comments about the medical importance of species of mosquitoes of Tabasco are discussed. Tabasco is the second state in Mexico with the largest mosquito richness (104 species), followed by Veracruz with 139 species.
The Asian bush mosquito, Aedes japonicus japonicus, and the coastal rock pool mosquito, Aedes togoi, are potential disease vectors present in both East Asia and North America. While their ranges are fairly well-documente...The Asian bush mosquito, Aedes japonicus japonicus, and the coastal rock pool mosquito, Aedes togoi, are potential disease vectors present in both East Asia and North America. While their ranges are fairly well-documented in Asia, this is not the case for North America. We used maximum entropy modeling to estimate the potential distributions of Ae. togoi and Ae. j. japonicus in the United States, Canada, and northern Latin America under contemporary and future climatic conditions. Our results suggest suitable habitat that is not known to be occupied for Ae. j. japonicus in Atlantic and western Canada, Alaska, the western, midwestern, southern, and northeastern United States, and Latin America, and for Ae. togoi along the Pacific coast of North America and the Hawaiian Islands. Such areas are at risk of future invasion or may already contain undetected populations of these species. Our findings further predict that the limits of suitable habitat for each species will expand northward under future climatic conditions.
The diversity of hard tick fauna was studied in different forest communities in 48 localities of eastern Croatia using the dragging-flagging method and by hand from ten different vertebrate hosts. A total of 2,225 specim...The diversity of hard tick fauna was studied in different forest communities in 48 localities of eastern Croatia using the dragging-flagging method and by hand from ten different vertebrate hosts. A total of 2,225 specimens comprising seven species in three genera were identified. Ixodes ricinus, the most abundant species (72.8% of all collected specimens) was recorded in 44 localities, followed by Dermacentor reticulatus in 19 localities, while the other five species (D. marginatus, H. concinna, H. inermis, I. canisuga, and I. hexagonus) were recorded in fewer localities. The highest ratio (67% of collected ticks) was in the adult stage with the predominance of females. The numbers of collected females, males, and nymphs of I. ricinus and H. concinna differed significantly. Ten new tick-host associations in Croatia were recorded. Fifty-three animals were infested with one tick species. Single species infestation with I. ricinus was found in 45.8% of animals, followed by D. reticulatus with 25.4%, D. marginatus with 10.2%, H. inermis and I. hexagonus with 3.4%, and I. canisuga with 1.7%. Coinfestation with two species of ticks were recorded in six animals. Ixodes ricinus, H. inermis, and D. reticulatus showed bimodal seasonal activity; for other species unimodal activity patterns were recorded.
In 2016, modified CO -baited encephalitis virus surveillance (EVS) traps were evaluated for flavivirus surveillance in the Northern Territory, Australia. The traps were fitted with honey-soaked nucleic acid preservation...In 2016, modified CO -baited encephalitis virus surveillance (EVS) traps were evaluated for flavivirus surveillance in the Northern Territory, Australia. The traps were fitted with honey-soaked nucleic acid preservation cards (FTA ) for mosquitoes to expectorate virus while feeding on the cards. Cards were tested for the presence of selected arboviruses, with two cards testing positive for Kunjin virus and Alfuy, while sentinel chickens tested in parallel also showed Kunjin virus activity at the same time. The results from the cards and vector mosquito feeding rates indicate that CO -baited EVS traps coupled with honey-baited FTA cards are an effective tool for broad-scale arbovirus surveillance.
In the present study, the effects of two spatial repellents (SR) were determined for Aedes aegypti and Ae albopictus, the main vectors of dengue, Chikungunya, and Zika fever. The modular high-throughput screening system...In the present study, the effects of two spatial repellents (SR) were determined for Aedes aegypti and Ae albopictus, the main vectors of dengue, Chikungunya, and Zika fever. The modular high-throughput screening system (HITSS) was used to evaluate the response of both species to transfluthrin and linalool SR at different concentrations. The highest spatial repellency results for Ae. aegypti were obtained by transfluthrin to 0.001% with 37.50 ± 4.33%, and for linalool to 10% with 77.50 ± 3.90%. For Ae. albopictus, the highest spatial repellency percentages for transfluthrin 0.01% were 45.00 ± 3.78%, and linalool at 1% and 10% were 56.25 ± 7.06% and 56.25 ± 6.46%, respectively. Transfluthrin caused high levels of mortality with 71.25 ± 6.66%, 79.75 ± 8.65%, and 100% to Ae. aegypti and 70.00 ± 5.98% and 98.75 ± 0.82% to Aedes albopcitus. With the results of this study, we concluded that both the transfluthrin and linalool could be used as protection measures against the bite of Ae. aegypti and Ae. albopictus in the integral strategies for the control of vectors in Mexico.
Mosquitoes use many cues to assess whether a habitat is conducive for reproduction, possibly including the presence of stimuli from aquatic macrophytes. The effect of water infusions of water hyacinth (Eichhornia crassip...Mosquitoes use many cues to assess whether a habitat is conducive for reproduction, possibly including the presence of stimuli from aquatic macrophytes. The effect of water infusions of water hyacinth (Eichhornia crassipes), water lettuce (Pista stratioles), parrotfeather (Myriophyllum aquaticum), and water pennywort (Hydrocotyle umbellata) on mosquito oviposition and attraction was investigated. Gravid Culex quinquefasciatus deposited significantly more egg rafts in water hyacinth, water lettuce, or Bermuda hay (positive control) infusions compared to water, while water pennywort and parrotfeather infusions did not differ from water. In-flight attraction responses of Cx. quinquefasciatus, Aedes aegypti, and Anopheles quadrimaculatus were evaluated. The strongest attraction of gravid Cx. quinquefasciatus and Ae. aegypti occurred in the presence of volatiles from infusions of water hyacinth and water lettuce, which were equal in attractiveness to hay infusion. Water pennywort and parrotfeather infusions were not attractive. Gravid An. quadrimaculatus were not attracted to aquatic plant volatiles. The results suggest that water hyacinth and water lettuce emit volatile chemicals that attract two of three mosquito species tested and stimulate oviposition by Cx. quinquefasciatus, demonstrating that the level of attraction of aquatic plant volatiles varies among species in ways that may have relevance to bait-based detection and control methods.
An entomological study was conducted in a Leishmania infantum focus, including the identification of the sand fly species, the detection and the characterization of Leishmania DNA in female sand flies, and blood meal ori...An entomological study was conducted in a Leishmania infantum focus, including the identification of the sand fly species, the detection and the characterization of Leishmania DNA in female sand flies, and blood meal origins in engorged sand flies. A total of 643 sand flies (31% female, 69% male) was identified based on their morphological features or molecular markers. Ten different species were identified, with Phlebotomus perniciosus, the confirmed vector of L. infantum, being the most abundant (56%), P. papatasi in 25% of sand flies, the unique vector species of L. major, and P. longicuspis in 7% of cases, the suspected second vector of L. infantum. Moreover, the infection rate was 3.4% in P. perniciousus, P. papatasi, P. longicuspis, and Sergentomya minuta. Also, L. infantum was identified in five unfed P. perniciosus and two P. longicuspis. Our results suggest the vector role of P. perniciosus and P. longicuspis in the transmission cycle of L. infantum. The DNA of four mammalian species (human, rabbit, horse, and cow) was identified in the blood meals of sand flies, suggesting that these species are potential reservoirs of leishmaniasis, though it is not yet fully elucidated (especially for MON-24 and MON-80). We suggest the existence of different transmission cycles of L. infantum involving different species of sand flies and hosts.