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The physical characteristics of a nematoceran fly that evokes the image of a mosquito of the genus Anopheles Meigen (Diptera: Culicidae) has existed since the genus was defined in the early part of the twentieth century. Is that image likely to change with the recent proposal to elevate four Neotropical subgenera to generic status based on relationships generated by phylogenetic analyses of mitochondrial protein-coding genes? Reasons for retaining the traditional concept of Anopheles, with its traditionally recognized subgenera, are presented. However, as the ranking of taxa as genera or subgenera is subjective, the choice of rank of a genus-group name may be considered a subjective decision and a matter of user preference.
Medically important flies that majority of them are classified to synanthropic flies can be mechanical vectors for some of contagious diseases to human and many animals. Also some species of their larvae are cause of myiasis in human and livestock animals. The aim of this study was to determine the geographical distribution of medically important flies in Iran using Geographical Information System (GIS). All published English and Persian documents on medically important flies of Iran from reliable medical sciences resources were gathered. A database was then designed in Excel format, including all available information regarding flies. The valid data were transferred to ArcGIS 10.3 to prepare the first spatial database of medically important flies and human myiasis foci of Iran. The Iran Medical Important Flies base includes 71 papers and three PhD/MSc theses, reporting studies conducted during 1977–2017.This database contains different available data covering their faunistic and all myiasis data reports related to flies of 102 species in nine families of medical important flies in Iran.Twenty-three out of the 31 provinces of Iran, had some reports of medically important flies. However, these flies have high species diversity, wide geographical distribution and with various ecological niches in different provinces in Iran. Besides that, there are many high-risk foci of human myiasis in a number of provinces of Iran.
Immature mosquitoes alter their foraging behavior in response to variation in nutrients, predators, and temperature, with consequences on the adult stage where pathogens are transmitted. These patterns of behavior have not been described with respect to both developmental stage and environmental variation, nor has behavior been examined within an individual across instars. We hypothesized that individual larvae have distinct behavioral syndromes, and predict that the rank of foraging activity in the third instar will be correlated with foraging activity in the fourth instar for an individual across all conditions. We also hypothesized that individuals that fail to achieve adulthood forage more intensely than those that will emerge due to the need for greater resources. To examine these hypotheses, we conducted an experiment in which we exposed 96 individual Aedes aegypti L. (Diptera: Culicidae) larvae to four combinations of temperature and nutrients. We recorded larvae in the third and fourth instar, and generated time budgets of active and passive foraging behaviors. We found correlations between individual behavior in the third and fourth instar when conditions were the most stressful (cool temperatures and low nutrients). Controlling for this intra-individual behavior, there was variation between instar behaviors, but this was dependent on both temperature and nutrients. We also found that larvae that failed to pupate within 28 d before emergence foraged more intensely than those that emerged. While we found no evidence that mosquitoes have distinct behavioral syndromes in Ae. aegypti, we did find support that nutrients and temperature affect behavior differently at different instars.
Studies on the bioecology of Haemagogus leucocelaenus Dyar and Shannon 1924, Haemagogus janthinomys Dyar 1921, Aedes albopictus Skuse 1895 (Diptera: Culicidae) mosquitos are extremely important from an epidemiologic point of view, as they are known to be vectors of many important pathogens and, therefore, act as the main factor responsible for the maintenance of several zoonoses natural cycles. The present work aimed to elucidate their seasonal egg-hatching rate using the immersion method. Ovitraps were used to collect mosquito eggs from an Atlantic Forest fragment, in the State of Rio de Janeiro, Brazil, from November 2015 to November 2016. After collection, the eggs were immersed 40 times to assess their hatching rate and evaluate the number of immersions resulting in the highest hatchability during the study period. Differences in the proportion of hatched eggs between species and seasons (spring, summer, fall, winter) and in the numbers of immersions in which eggs hatched were assessed using odds ratios. Hg. leucocelaenus was the species with the highest number of eggs hatching in all sampling periods, followed by Ae. albopictus. Most Ae. albopictus eggs hatched on first immersion regardless of season. Both the numbers of eggs and the number of immersion in which the Haemagogus eggs hatched showed high variability within seasons. In spring, the proportion of eggs that hatched on the first compared to further immersions was similar, while in fall and winter a higher percentage (over 94%) of Hg. leucocelaenus eggs hatched on the first immersion; the opposite pattern was observed in the summer. These results differ from previous observations linking increased hatching to warmer months. The number of immersions in which Hg. leucocelaenus eggs hatched varied between seasons, however differences were not statistically significant. These results evidence the need for further studies to elucidate factors that influence hatching patterns.
An essential strategy to deal with mosquito-borne diseases is the control of larvae in their development sites. The mosquitoes Anopheles pseudopunctipennis (Theobald) (Diptera: Culicidae), a malaria vector, and Aedes aegypti (L.) (Diptera: Culicidae), vector of dengue, Zika, yellow fever, and chikungunya viruses, breed in very different habitats. Insecticide treatments of mosquito larvae focus mainly on their lethal effects. However, insecticide degradation or the poor dosage of larvicides will invariably lead to the sublethal exposure of a target (and nontarget) species, the nonlethal effects of these compounds may have important effects on vital insect activities, and therefore their evaluation is necessary. In this study, we assessed the survival and swimming behavior of larvae of Ae. aegypti and An. pseudopunctipennis exposed to increasing concentrations of three larvicides. We found that Ae. aegypti, was more sensitive to the larvicides than An. pseudopunctipennis, we also observed an overall decrease in the movement of those larvae of both species, which survive the treatments. This decrease might have ecological relevance in their natural habitats, increasing the chance to be predated and decreasing their ability to obtain food. Finally, this information will be valuable to assist authorities to make decisions in the implementation of further control programs.
Aedes aegypti (L.) (Diptera: Culicidae) is a vector of many medically significant viruses in the Americas, including dengue virus, chikungunya virus, and Zika virus.Traits such as longevity, fecundity, and feeding behavior contribute to the ability of Ae. aegypti to serve as a vector of these pathogens. Both local environmental factors and population genetics could contribute to variability in these traits. We performed a comparative study of Ae. aegypti populations from four geographically and environmentally distinct collection sites in Argentina in which the cohorts from each population were held at temperature values simulating a daily cycle, with an average of 25°C in order to identify the influence of population on life-history traits. In addition, we performed the study of the same populations held at a daily temperature cycle similar to that of the surveyed areas. According to the results, Aguaray is the most outstanding population, showing features that are important to achieve high fitness. Whereas La Plata gathers features consistent with low fitness. Iguazu was outstanding in blood-feeding rate while Posadas's population showed intermediate values. Our results also demonstrate that climate change could differentially affect unique populations, and that these differences have implications for the capacity for Ae. aegypti to act as vectors for medically important arboviruses.
Calliphoridae are among the first insects associated to decomposing animal remains. We have collected 1,841 specimens of three calliphorid genera: Calliphora, Lucilia, and Chrysomya, from different Lebanese localities as a first step in implementing a database of insects of forensic relevance for the country. Blow-flies are crucial for the estimation of the postmortem interval. DNA-based identification is a rapid and accurate method, often used for morphologically similar species, especially for immatures or incomplete specimens. In this study, we test the suitability of three genetic markers to identify adults and immature stages of calliphorids, viz., mitochondrial cytochrome c oxidase subunit I (COI) barcode, a region including partial sequences of mitochondrial Cyt-b-tRNAser-ND1, and second internal transcribed spacer (ITS2) region of nuclear ribosomal DNA. Forty Lebanese specimens of various developmental stages (egg, larva, wandering third instar, pupa, newly emerged adult, and mature adult) were identified among the three calliphorid genera: Calliphora, Lucilia, and Chrysomya, and compared with published sequences to confirm their specific assignation. Phylogenetic analyses showed the robustness of ITS2 and COI to identify calliphorids at species level. Nevertheless, ITS2 failed to discriminate Lucilia caesar (Linnaeus) (Diptera, Calliphoridae) from Lucilia illustris (Meigen) (Diptera, Calliphoridae), and COI had a similar issue with Lucilia sericata (Meigen) (Diptera, Calliphoridae) and Lucilia cuprina (Wiedemann) (Diptera, Calliphoridae).Thus, these two markers are complementary. This work contributes new nucleotide sequences for Lebanon. It is a first step in implementing a molecular database of forensic relevant insects for the country.
Crimean Congo hemorrhagic fever is a zoonotic disease which has emerged or re-emerged recently in Eastern Europe andTurkey.The causative agent is a virus, mainly transmitted by ticks of the species Hyalomma marginatum (Koch, 1844, Ixodida, Amblyommidae).To test potential scenarios for the control of pathogen spread, a dynamic mechanistic model has been developed that takes into account the major processes involved in tick population dynamics and pathogen spread.The tick population dynamics model represents both abiotic (meteorological variables) and biotic (hare and cattle densities) factors in the determination of processes (development, host finding, and mortality).The infection model consists of an SIRS model for the host part whereas a lifelong infectiousness was considered for ticks. The model was first applied to a zone in Central Anatolia (Turkey). Simulated dynamics represent the average reported level of infection in vectors and hosts. A sensitivity analysis to parameter value has been carried out and highlighted the role of transstadial transmission as well as acquisition of the pathogen by immature stages. Applying the model to different sites ofTurkey shows different patterns in the dynamics of acarological risk (number of infectious questing adults). This model was thereafter used to test control strategies. Simulation results indicate that acaricide treatments and decrease in hare density could have valuable effects when combined, either on the acarological risk or on the prevalence in cattle.The kind of model we have developed provides insight into the ability of different strategies to prevent and control disease spread.
Ixodes pacificus Cooley & Kohls (Acari: Ixodidae), the primary vector of Lyme disease spirochetes to humans in the far-western United States, is broadly distributed across Pacific Coast states, but its distribution is not uniform within this large, ecologically diverse region. To identify areas of suitable habitat, we assembled records of locations throughout California where two or more I. pacificus were collected from vegetation from 1980 to 2014. We then employed ensemble species distribution modeling to identify suitable climatic conditions for the tick and restricted the results to land cover classes where these ticks are typically encountered (i.e., forest, grass, scrub-shrub, riparian). Cold-season temperature and rainfall are particularly important abiotic drivers of suitability, explaining between 50 and 99% of the spatial variability across California among models. The likelihood of an area being classified as suitable increases steadily with increasing temperatures >0°C during the coldest quarter of the year, and further increases when precipitation amounts range from 400 to 800 mm during the coldest quarter, indicating that areas in California with relatively warm and wet winters typically are most suitable for I. pacificus. Other consistent predictors of suitability include increasing autumn humidity, temperatures in the warmest month between 23 and 33°C, and low-temperature variability throughout the year. The resultant climatic suitability maps indicate that coastal California, especially the northern coast, and the western Sierra Nevada foothills have the highest probability of I. pacificus presence.
Eastern Equine Encephalitis Virus (EEEV) is the most pathogenic arbovirus endemic to the United States. EEEV primarily infects birds but can be fatal to humans, horses, and some other mammals. Although EEEV transmission occurs in the Northeastern, Southeastern, and Midwestern United States, the largest number of horse and human cases have been reported in Florida, the only state where transmission occurs year round. Currently, a GIS-based risk index (RI) model is used to map EEE transmission risk to horses in Florida. This study validates that RI model using a 5-yr dataset of horse cases in Florida. RI values were similar between summer (N = 152, x = 0.59) and winter (N = 25, x = 0.66) cases, suggesting the model is effective for mapping risk during both transmission seasons.These risk values were larger and remained similar when a 100-m buffer was applied to the case locations to account for modest spatial errors in case reporting (summer x = 0.73, winter x = 0.77). In both comparisons, RI values for summer and winter cases were higher than expected at random in the Panhandle, North, and Central regions of the state, although the analysis was inconclusive in the South, where only two cases were observed.This suggests the RI map could be used to target EEEV surveillance, prevention, and control efforts in both transmission seasons in Florida.
Muscid Flies (Diptera: Muscidae) are of great forensic importance due to their wide distribution, ubiquitous and synanthropic nature. They are frequently neglected as they tend to arrive at the corpses later than the flesh flies and blow flies. Moreover, the lack of species-level identification also hinders investigation of medicolegal purposes. To overcome the difficulty of morphological identification, molecular method has gained relevance. Cytochrome c oxidase subunit I (COI) gene has been widely utilized. Nonetheless, to achieve correct identification of an unknown sample, it is important to survey certain muscid taxa from its geographic distribution range. Accordingly, the aim of this study is to contribute more geographically specific. We sequenced the COI gene of 51 muscid specimens of 12 species, and added all correct sequences available in GenBank to yield a total data set of 125 COI sequences from 33 muscid species to evaluate the COI gene as a molecular diagnostic tool.The interspecific distances were extremely high (4.7–19.8%) in either the standard barcoding fragment (658 bp) or the long COI sequence (1,019–1,535 bp), demonstrating that these two genetic markers were nearly identical in the species identification. However, the intraspecific distances of the long COI sequences were significantly higher than the barcoding region for the conspecific species that geographical locations vary greatly.Therefore, genetic diversity presented in this study provides a reference for species identification of muscid flies. Nevertheless, further investigation and data from more muscid species are required to enhance the efficacy of species-level identification using COI gene as a genetic marker.
The Simulium aureum group (Diptera: Simuliidae), also known as subgenus Eusimulium Roubaud, is a monophyletic, Holarctic taxon of bird-feeding black flies with a reduced chromosome number of two and remarkably similar external structure in all life stages. We analyzed the banding patterns of the polytene chromosomes to understand the composition of this species group along the northern coast of the Black Sea where two little-known nominal species have their type localities. Our analyses link the names Simulium krymense (Rubtsov) and Simulium maritimum (Rubtsov) with unique chromosomal characters, indicate that both are male chiasmate, and reveal the presence of Simulium angustipes Edwards along the northern coast of the Black Sea for the first time. We show that S. krymense has a banding sequence most similar to the hypothesized ancestral form of the S. aureum group, and that the entire group is derived from within the Simulium vernum group, rendering the latter group and its encompassing subgenus, Nevermannia Enderlein, paraphyletic.
Mosquitoes are intensely studied as vectors of disease-causing pathogens, but we know relatively less about microbes that naturally reside in mosquitoes. Profiling resident bacteria in mosquitoes can help identify bacterial groups that can be exploited as a strategy of controlling mosquito populations. High-throughput 16S rRNA gene sequencing and traditional culture-based methods were used to identify bacterial assemblages in Culex quinquefasciatus Say (Diptera: Culicidae) in a tissue- and stage-specific design. In parallel, wild host Cx. quinquefasciatus was compared with our domestic strain. 16S rRNA genes survey finds that Cx. quinquefasciatus has taxonomically restricted bacterial communities, with 90% of its bacterial microbiota composed of eight distinctive bacterial groups: Nocardioidaceae (Actinomycetales), Microbacteriaceae (Actinomycetales), Flavobacteriaceae, Rhizobiales, Acetobacteraceae, Rickettsiaceae, Comamondaceae (Burkholderiales), and Enterobacteriaceae. Taking into account both metagenome- and culture-based methods, we suggest three bacterial groups, Acetobacteraceae, Flavobacteriaceae, and Enterobacteriaceae, as candidates for mutualists in Cx. quinquefasciatus. Members of these three bacterial families have been studied as mutualists, or even as symbionts, in other insect groups, so it is quite possible they play similar roles in mosquitoes.
Anopheles subpictus Grassi is considered a secondary malaria vector in parts of Asia.The current study determined some ecological and bionomical characteristics of this species in southeastern Iran. The temporal patterns of abundance, resting behavior, blood feeding activity, host selection, adult susceptibility to insecticides and larval habitats were investigated. Most adults were collected by pyrethrum space-spray collection, followed by pit shelters and outlet window traps, respectively. The abdominal condition index of gravid to blood fed females resting outdoors was more than one, thereby showing exophilic resting behavior. Only 25% of engorged females tested positive for human blood, even though most of the samples were collected from houses. The host seeking activity of An. subpictus was bimodal with peaks at 22–2300 h and 03–0400 h. Also, the relative abundance showed peaks in March and December.The results of susceptibility tests showed a resistance of field strains to DDT. Future studies are needed to investigate the possible role of this species in malaria transmission in southeastern Iran.
The mosquito fauna (Diptera: Culicidae) from two remote localities along the Araçá River, within the Municipality of Barcelos, towards the northern border of the Brazilian State of Amazonas, were sampled using CDC, Shannon, Malaise, and Suspended traps, along with net sweeping and immature collections. During June 2010, 111 collections yielded more than 23,500 mosquitoes distributed in 15 genera, representing 119 different species, together with eight morphospecies, which may represent undescribed new taxa. Among the species collected, there is one new distributional record for Brazil and nine new distributional records for the State of Amazonas.With the highest number of species, the genus Culex Linnaeus also had the largest number of individuals followed by Aedes Meigen with the second highest number of species. The most abundant species was Culex (Melanoconion) gnomatos Sallum, Hutchings & Ferreira followed by Culex (Melanoconion) portesi Senevet & Abonnenc, Culex (Culex) mollis Dyar & Knab, Aedes (Ochlerotatus) fulvus (Wiedemann), Culex (Melanoconion) pedroi Sirivanakarn & Belkin, Culex (Melanoconion) crybda Dyar, Aedes (Ochlerotatus) nubilus (Theobald), and Anopheles (Anopheles) peryassui Dyar & Knab. The epidemiological implications of mosquito species found are discussed and are compared with other mosquito inventories from the Amazon region. As the first standardized mosquito inventory of the Araçá River, with the identification of 127 species level taxa, the number of mosquito species which have been collected along the northern tributaries of the middle Rio Negro Basin (i.e., Padauari and Araçá Rivers) increased significantly.
Abundance of sarcosaprophagous Calyptratae species was monitored by using baited traps and active captures with hand net. Analysis of field data collected in three protected areas in the Valdivian temperate forest of South America (Lanín National Park, Lago Puelo National Park, and Los Alerces National Park) indicated that bottle traps baited with putrescine is a reliable method to estimate local abundance of sarcosaprophagous species by comparison to the active capture method. Also, we describe and compare general patterns of sex bias for four dominant species: Sarconesia magellanica (Le Guillou), Calliphora vicina Robineau-Desvoidy, Microcerella spinigena (Rondani), and Oxysarcodexia varia (Walker). From these analyses, it can be concluded that abundance fluctuations of flies showed significant relationship between the sampling methods. This study showed that besides the expected interspecific differences in trapping efficiency, there are acute intraspecific differences of sex ratios between sampling methods.
Vector Control, Pest Management, Resistance, Repellents
Clothing treated with the pyrethroid permethrin is available in the United States as consumer products to prevent tick bites. We used tick bioassays to quantify contact irritancy and toxicity of permethrin-treated clothing for three important tick vectors of human pathogens: the blacklegged tick, Ixodes scapularis Say (Acari: Ixodidae); the lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae); and the American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae). We first demonstrated that field-collected I. scapularis nymphs from Minnesota were as susceptible as laboratory-reared nymphs to a permethrin-treated textile. Field ticks examined in bioassays on the same day they were collected displayed contact irritancy by actively dislodging from a vertically oriented permethrin-treated textile, and a forced 1-min exposure resulted in all ticks being unable to move normally, thus posing no more than minimal risk of biting, 1 h after contact with the treated textile. Moreover, we documented lack of normal movement for laboratory-reared I. scapularis nymphs by 1 h after contact for 1 min with a wide range of permethrin-treated clothing, including garments made from cotton, synthetic materials, and blends. A comparison of the impact of a permethrin-treated textile across tick species and life stages revealed the strongest effect on I. scapularis nymphs (0% with normal movement 1 h after a 1-min exposure), followed by A. americanum nymphs (14.0%), I. scapularis females (38.0%), D. variabilis females (82.0%), and A. americanum females (98.0%). Loss of normal movement for all ticks 1 h after contact with the permethrin-treated textile required exposures of 1 min for I. scapularis nymphs, 2 min for A. americanum nymphs, and 5 min for female I. scapularis, D. variabilis, and A. americanum ticks. We conclude that use of permethrin-treated clothing shows promise to prevent bites by medically important ticks. Further research needs are discussed.
Phlebotomine sand flies (Diptera: Psychodidae) are primary vectors of leishmaniasis. Greece and Turkey are both endemic for visceral and cutaneous leishmaniasis and are widely affected by the disease. Measures commonly applied for controlling sand flies rely on the use of insecticides, predominantly pyrethroids. A worldwide problem associated with the intensive use of insecticides is the development of resistance. Scarce information is available regarding the resistance status in sand fly populations. Sand flies were collected from Greece (Thessaloniki, Peloponnese, Chios island) and Turkey (Sanliurfa) and analyzed for the presence and frequency of target-site knockdown resistance mutations on the voltage-gated sodium channel (Vgsc) gene. Five sand fly species were included in the analysis: Phlebotomus perfiliewi Parrot, Phlebotomus neglectus Tonnoir, Phlebotomus simici Nitzulescu, Phlebotomus tobbi Adler and Theodor, and Phlebotomus papatasi Scopoli. Their Vgsc gene—domain II was analyzed for the presence of known pyrethroid resistance mutations. The mutation 1014F, associated with pyrethroid-resistant phenotypes, was detected in P. papatasi sand flies from Sanliurfa at an allele frequency of 48%. Homozygotes for the wild type allele 1014L (Leu/Leu) represented 36% of the population, while homozygotes for the resistant allele 1014F (Phe/Phe) and heterozygotes encompassing both alleles (Leu/Phe) each had a frequency of 32%. In all other sand fly species, only the wild type allele 1014L was detected. This is the first report for the detection of resistance mutations in the major leishmaniasis vector P. papatasi and is of major concern regarding leishmaniasis control.
Culex quinquefasciatus is a common domestic mosquito that is widespread in many areas of Thailand and serves as a southeastern vector of Japanese encephalitis. The present study investigated the acute toxicity of crude extracts and alkaloid compounds of Piper retrofractum (Piperales: Piperaceae) in Cx. quinquefasciatus third instar larvae. P. retrofractum was sequentially extracted using hexane, dichloromethane, ethyl acetate, and methanol, and the crude extracts were tested on mosquito larvae. Detoxification and neuroenzymes were analyzed to establish the mode of action. Acute toxicity was assessed on Poecilia reticulata (Cyprinodontiformes: Poeciliidae) to determine the possibility of toxicity in a nontarget species. Our results showed crude hexane extract had the highest toxicity in Cx. quinquefasciatus (0.9 ppm). Piperine and piperanine, which are alkaloid compounds from the crude hexane extract, showed LC50 values of 0.27 and 2.97 ppm, respectively, after 24 h of exposure. All the crude extracts showed low toxicity in P. reticulata compared with that in the mosquito larvae. The carboxylesterase, glutathione-S-transferase, and acetylcholinesterase activities in Cx. quinquefasciatus were reduced after treatment with all the extracts and the two alkaloid compounds.Thus, P. retrofractum shows larvicidal effects against Cx. quinquefasciatus and low toxicity for nontarget species. Thus, P. retrofractum could be a choice for controlling Cx. quinquefasciatus.
Documented resistance to traditional insecticides in the house fly, Musca domestica L. (Diptera: Muscidae), has expedited a need for alternative forms of control. One such method is the use of biological control organisms, such as the entomopathogenic fungus, Beauveria bassiana (Balsamo – Crivelli) Vuillemin (Hypocreales: Clavicipitaceae). Administering B. bassiana with a calorically rich phagostimulant such as sucrose may have the unintended effect of increasing fly vitality and thus reproduction before mortality sets in. Therefore, finding a phagostimulant with lower caloric value that can replace sucrose is valuable. Here B. bassiana was combined with the sweeteners erythritol and xylitol as potential low-calorie substitutes for sucrose. Female flies consumed as much xylitol alone as they did sucrose alone, but less erythritol than both. After 24 h of exposure, B. bassiana administered at 1 mg in erythritol and in sucrose were equally effective at reducing survival and better than xylitol. B. bassiana administered at 10 mg worked equally well at reducing survival in all three sweeteners. When exposed to 10 mg of B. bassiana in sweetener for 1 h, sucrose reduced survival more than in erythritol or xylitol, but mortality was still in excess of 97% after 8 d in all three sweeteners. Each sweetener mixed with B. bassiana worked as well in an environment with additional food sources and stimuli as they did in an environment lacking these additions. Erythritol and xylitol appear to be strong candidates to replace sucrose in baits formulated around B. bassiana.
An international team of scientists and veterinarians was assembled in 1999 to develop a monitoring program to determine the susceptibility of cat fleas, Ctenocephalides felis felis (Bouché) (Siphonaptera: Pulicidae), to imidacloprid. Cat flea eggs were collected, shipped to laboratories, and tested for their susceptibility to imidacloprid. Over 3,000 C. felis populations were collected from 2002 to 2017 from 10 different countries. Of these, 66.3% were collected from cats and 33.7% from dogs. C. f. felis populations (n = 2,200) were bioassayed by exposing cat flea eggs and the emerging larvae to a Diagnostic Dose (DD) of 3 ppm imidacloprid in larval rearing medium. Flea eggs hatched and developed in the untreated controls in 1,837 of the isolates (83.5%) bioassayed. Flea isolates (n = 61) that had ≥5% survival at the DD of 3 ppm were retested with a second DD of 3 ppm. None of them had ≥5% survival to the second dose of 3 ppm. Of the 1,837 valid C. felis isolates tested, there has been no evidence of a decreased susceptibility to imidacloprid over the past 17 yr. The methods outlined in this article should provide an acceptable protocol for testing many of the new active ingredients that have been registered for cat flea control.
A survey conducted from 2002 to 2012 of 759 customers from 84 veterinary practices allows us to examine the habits of dog and cat owners regarding the use of insecticides for flea control. The results indicate that the percentage of animals treated during the 12 mo prior to the survey was not very high (71% in dogs and 50% in cats), considering that 100% of animals included in the study were flea-infested. Statistical analysis shows that animals older than 4 mo are treated more frequently and that dogs are more likely to be treated than cats. Among cats, those living in houses with gardens or farms are treated at a higher rate than those that live in houses without gardens or in flats. The main variable associated with the degree of satisfaction and product loyalty is the active ingredient, and the choice of a commercial product is generally associated with high-efficacy products.The mode of application of a flea treatment does not seem to have a strong influence on pet owner satisfaction or loyalty. Likewise, we do not find a clear correlation between owners' satisfaction and loyalty, so pet owners may find the results of the selected product more or less satisfactory for reasons other than simple effectiveness. Finally, because of the complexity of the life cycle of these ectoparasites, the importance of the advice of a veterinarian when planning flea control is emphasized.
Salmonella Typhimurium (Le Minor and Popoff 1987; Enterobacteriales: Enterobacteriaceae) is a pathogen that causes gastroenteritis in humans and can be harbored by house flies. Factors influencing excretion of S. Typhimurium from infected flies have not been elucidated but are essential for assessing transmission potential. We determined the persistence and excretion of a green fluorescent protein (GFP) expressing strain of S.Typhimurium from house flies. Individual male and female flies were fed either sterile Luria-Bertani (LB) broth (controls) or cultures of “high” (~105 colony forming units [CFU]) or “low” (~104 CFU) doses of bacteria (treatments). Bacterial persistence was determined over 16 h by culturing whole-fly homogenate. Both sex and dose affected persistence between 6 and 12 h postingestion. In a separate experiment, fly excretion events were monitored during this time interval and excreta droplets were individually cultured for bacteria. Female flies had more excretion events than males across treatments. We observed interactions of fly sex and bacterial abundance (dose), both on the proportion of Salmonella-positive droplets and the CFU shed per droplet (CFU/droplet). In the low-dose treatment, males excreted a greater proportion of positive droplets than females. In the high-dose treatment, males excreted more CFU/droplet than females. High-dose male flies excreted more CFU/droplet than low-dose males, but low-dose females excreted more CFU/droplet than high-dose females. Irrespective of sex, low-dose flies excreted a greater dose-adjusted CFU (CFU droplet/CFU fed) than high-dose flies. This study demonstrates that both bacterial abundance and fly sex may influence excretion of bacteria from flies, and should be considered when assessing the risk of house fly transmission of pathogens.
This study reports a novel species of Babesia in unfed Rhipicephalus sanguineus sensu lato and its phylogenetic relationship to other species. One-hundred and forty DNA samples extracted from tick pools comprising 5,403 unfed R. sanguineus s.l. ticks were screened for Babesia. Overall Babesia infection was detected in female, male, and nymph pools with an infection rate maximum likelihood estimate (MLE) of 1.98 (CI 0.65–4.74), 0.50 (CI 0.03–2.40), and 0.07 (CI 0.01–0.21), respectively.Three adult female tick pools (MLE 1.44, CI 0.38–3.88) and one adult male pool (MLE 0.50, CI 0.03–2.40) hybridized to the catchall and Babesia genus probes but did not hybridize to any species-specific probe tested, suggesting the presence of an unidentified Babesia species. Phylogenetic analysis and sequencing revealed the newly detected Babesia isolate to form a clade distinct from fully identified canine, bovine, equine, and ovine Babesia species, with a range of 88.6–92.9% nucleotide identity.
In Thailand, leishmaniasis is an emerging vector-borne disease that has become a public health concern. In related epidemiological surveys to identify potential Leishmania vectors in the affected areas, DNA of Leishmania martiniquensis (Kinetoplastida: Trypanosomatidae) was detected in Sergentomyia (Neophebotomus) gemmea (Diptera: Psychodidae) and Sergentomyia (Parrotomyia) barraudi (Diptera: Psychodidae). Recently, a more elaborate study was conducted in the same areas that included sand fly species identification, screening sand flies for the presence of Leishmania DNA and blood meal analysis to identify potential reservoir hosts directed toward assessing the risk of human infection. Twenty-nine archived pools of sand flies collected in Hat Samran District, Trang Province were used in this study. Sand fly species were confirmed using PCR encompassing regions within the mitochondrial DNA. Leishmania DNA was detected using PCR of the heat shock protein 70 region (hsp70-PCR) and blood meal identification was performed using PCR of the cyt b gene of vertebrate mitochondrial DNA (cytbnd1-PCR) and human-specific AluYb8 repeat (AluYb8-PCR). Four sand fly species were confirmed, i.e., Phlebotomus (Anaphlebotomus) stantoni (Diptera: Psychodidae), S. barraudi, Sergentomyia (Neophlebotomus) iyengari (Diptera: Psychodidae), and S. gemmea. Leishmania siamensis was detected in one female S. iyengari. Only human blood was detected in P. stantoni and S. gemmea, while both sun skink (Mabuya multifasciata) and human blood were detected in S. iyengari. In this study, we showed that S. iyengari could be a potential vector of L. siamensis infection among humans.
The American dog tick, Dermacentor variabilis (Say), is a vector of spotted fever group (SFG) rickettsiae, including Rickettsia rickettsii the causative organism of Rocky Mountain spotted fever (RMSF). In North Carolina, SFG rickettsioses (including RMSF) are a leading cause of tick-borne illness. Knowledge of the infection rate and geographic distribution of D. variabilis ticks infected with Rickettsia spp. provides information on the spatial distribution of public health risk. Accordingly, we extracted genomic DNA from adult D. variabilis collected from field habitats in 32 North Carolina counties from 2009 to 2013. A nested PCR assay of the 23S-5S intergenic spacer (IGS) region of Rickettsia coupled with reverse line blot hybridization (RLBH) with species-specific probes was used to detect and identify rickettsiae to species. Approximately half of the 532 tick DNA samples exhibited a band of the expected size on agarose gels, indicating infection with Rickettsia spp. RLBH analyses showed R. amblyommatis (formerly ‘Candidatus R. amblyommii’), R. parkeri, and R. montanensis were predominant, while other Rickettsia species detected included R. conorii-like, R. massiliae, R. rhipicephali, R. canadensis, R. bellii, and some unknown Rickettsia spp. Some ticks were infected with more than one Rickettsia species. Notably, several Rickettsia-positive ticks harbored R. rickettsii. DNA sequencing was performed on a portion of the 23S-5S IGS amplicons and the results were concordant with RLB assay results. We conclude that Rickettsia spp. are common in D. variabilis in North Carolina. Geographic patterns in the occurrence of Rickettsia-infected D. variabilis ticks across the counties sampled are discussed.
Few studies have been able to provide experimental evidence of the ability of fleas to maintain rodent-associated Bartonella infections and excrete these bacteria.These data are important for understanding the transmission cycles and prevalence of these bacteria in hosts and vectors. We used an artificial feeding approach to expose groups of the oriental rat flea (Xenopsylla cheopis Rothschild; Siphonaptera, Pulicidae) to rat blood inoculated with varying concentrations of Bartonella elizabethae Daly (Bartonellaceae: Rhizobiales). Flea populations were maintained by membrane feeding on pathogen-free bloodmeals for up to 13 d post infection. Individual fleas and pools of flea feces were tested for the presence of Bartonella DNA using molecular methods (quantitative and conventional polymerase chain reaction [PCR]). The threshold number of Bartonellae required in the infectious bloodmeal for fleas to be detected as positive was 106 colony-forming units per milliliter (CFU/ml). Individual fleas were capable of harboring infections for at least 13 d post infection and continuously excreted Bartonella DNA in their feces over the same period. This experiment demonstrated that X. cheopis are capable of acquiring and excreting B. elizabethae over several days.These results will guide future work to model and understand the role of X. cheopis in the natural transmission cycle of rodent-borne Bartonella species. Future experiments using this artificial feeding approach will be useful for examining the horizontal transmission of B. elizabethae or other rodent-associated Bartonella species to naïve hosts and for determining the viability of excreted bacteria.
First autochthonous Zika clinical case was reported in the Republic of Marshall Islands (RMI) on Majuro Atoll in February 2016. An entomological survey of mosquito larvae and adult populations was carried out in four areas of Majuro, the most populated atoll of RMI encompassing different habitats (forest, rural, or urban) including some with confirmed clinical Zika cases to evaluate which mosquito species could be involved in the Zika transmission. A total of 2,367 immature and adult mosquito specimens were collected and identified to the species level. In total, five mosquito species were detected, Aedes aegypti (Linnaeus), Aedes albopictus (Skuse), Aedes marshallensis (Stone and Bohart), Culex quinquefasciatus (Say), and Culex annulirostris (Skuse) (Diptera: Culicidae), a first record for RMI. The most abundant species was Ae. aegypti presumed to be the main vector of Zika virus followed by Ae. albopictus. Improved management of breeding containers through better public awareness and community engagement, mosquito surveillance and innovative mosquito control strategies using the sterile insect technique (SIT) and/or the incompatible insect technique (IIT) could help prevent outbreaks of arboviruses in the RMI.
Scented sugar baits deployed in California deserts detected early West Nile virus (WNV) transmission by mosquitoes, representing a potential improvement to conventional arbovirus surveillance that relies heavily on infection rates in mosquito pools. In this study, we expanded deployment of scented sugar baits into suburban Sacramento and Yolo (2015, 2016) and Riverside Counties (2016), California.The goal of the study was to determine whether scented sugar baits detect WNV and St. Louis encephalitis virus (SLEV) concurrent with mosquito infections in trapped pools in areas of high human density. Between 8 and 10% of sugar baits were WNV RNA positive in both study years across the three counties. In Riverside County, where SLEV re-emerged in 2015, 1% of sugar baits were SLEV positive in 2016. Rates of sugar bait positives were at least 100 times higher than infection rates in trapped mosquitoes in the same districts.The prevalence of sugar bait positives varied temporally and did not coincide with infections in mosquitoes collected at the same sites each week. WNV RNA positive sugar baits were detected up to 2 wk before and after concurrent surveillance detected infection in mosquito pools at the same sites. Sugar baits also detected WNV in Riverside County at locations where no WNV activity was detected in mosquito pools. Sugar baits generated between 0.8 and 1.2 WNV positives per $1,000 and can be more economical than carbon dioxide baited traps that produce 0.8 positives per $1,000. These results indicate that the sugar bait approach enhances conventional arbovirus surveillance in mosquitoes in suburban California.
With the establishment of Zika virus in the Americas, an accurate understanding of the geographic range of its primary vector, Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae), is vital to assessing transmission risk. In an article published in June 2016, Hahn and colleagues compiled county-level records in the United States for the presence of Ae. aegypti and Aedes (Stegomyia) albopictus (Skuse) (Diptera: Culicidae) reported between January 1995 and March 2016. Despite ecological suitability for both mosquito species along the Gulf Coast, Ae. aegypti was not reported in Alabama during the time interval, a result consistent with research suggesting that interactions between these two species often result in displacement of Ae. aegypti. Herein, we report the detection of Ae. aegypti populations in Mobile, Alabama, after a 26-yr absence and present findings on human perceptions of Zika virus relevant to transmission. It is unclear whether the specimens (69 out of 1074) represent a recent re-introduction or belong to a previously undetected remnant population. Sequencing of mtDNA from identified Ae. aegypti matched closest to a specimen collected in Kerala, India. A survey of residents in the surveillance area suggests high encounter rates with mosquitoes in and around homes. Despite high self-reported knowledge about Zika virus, the survey revealed gaps in knowledge regarding its transmission cycle and relative degrees of vulnerability to serious illness among segments of the human population. These findings highlight the importance of continued surveillance, vector control, and public-health education in Gulf Coast states, as well as the potential threat of Ae. Aegypti–transmitted pathogens in southern Alabama.
Haematobia irritans (L.) (Diptera: Muscidae) were netted from pastured cattle in California over two summers, with the goal of documenting on-host sex ratios and mating success as they might vary with repellent applications. Sex ratios were calculated from 100 adults per herd per date, and mating status of females (n = 30 per herd per date) was assessed by dissection of spermathecae. Flies were collected before, during, and after 2-wk treatment periods with each of two repellent-oil mixtures: a 15% mixture of fatty acids (C8, C9, C10) in mineral oil or a 2% solution of geraniol in mineral oil. During the treatment period, flies were collected 3–4 d after the prior treatment and immediately before the next treatment. A separate herd used in the second year was untreated. Overall, the proportion female was 0.65 ± 0.01 (mean ± SE) (range 0.28–0.81). Sex ratios were not altered over time by treatments with either repellent. Overall, proportion of females mated was 0.744 ± 0.018 (range 0.40–1.00). Mating status was significantly affected by the two repellent treatments, which did not differ from each other. For treatment herds, proportion mated before treatment was 0.789 ± 0.039, dropping significantly to 0.659 ± 0.038 during the treatment period, and rebounding to 0.750 ± 0.035 after treatments ceased. Treatments probably killed or repelled the existing heterogeneous fly population, and during treatment relatively more flies were unmated recent arrivals.
Ultraviolet (UV) radiation is a key limiting factor for biological pest control with entomopathogenic fungi. While little is known about the impact of UV on Metarhizium anisopliae Metchnikoff (Sorokin) (Hypocreales: Clavicipitaceae) conidia in aquatic mosquito-breeding sites, this study determined the effect of UV-B on the viability and virulence of M. anisopliae sensu lato (s.l.) strain IP 46 in the laboratory against Aedes aegypti (L.) (Diptera: Culicidae) larvae. Conidia were treated in cups under defined water depths (0, 1, 2, and 3 cm) to six different UV-B doses (0, 0.657, 1.971, 3.942, 7.884, 11.826, or 15.768 kJ m-2) at 27 ± 2°C. The ability of treated conidia to germinate up to 24 h postexposure on PDAY + benomyl + chloramphenicol medium at 25 ± 1°C was adversely affected by higher doses of UV-B radiation regardless of the water depth. Germination, however, did not fall below 70% regardless of the test conditions. In fact, conidial virulence against second-instar larvae was not affected by either the water depth (F3,84 = 0.3, P = 0.85) or any tested levels of UV-B radiation (F6,21 ≤ 1.2, P ≥ 0.39) including those distinctly higher than might be expected for tropical sites. These findings strengthen previous observations that IP 46 has significant potential for use against A. aegypti larvae, even when exposed to elevated UV-B irradiance levels in the small breeding sites that are common for this important vector.
Microsatellite loci specifically designed and optimized for secondary vectors and neglected species of mosquitoes are lacking. Cross-species transferability of microsatellite loci between close taxa has been used as a reliable option, being successfully done for Aedes taeniorhynchus Wiedemann (Diptera: Culicidae), Triatoma sordida Stål (Hemiptera: Reduviidae), and Aedes fluviatilis Lutz (Diptera: Culicidae). Nonetheless, prior to the utilization of transferred microsatellites, they must be assessed for their performance and reliability on the target species. Therefore, the goal of this study was to transfer and validate SSR primers previously developed for the Culex pipiens complex to Culex (Culex) nigripalpus Theobald (Diptera: Culicidae). Culex nigripalpus were collected in seven different locations throughout the city of São Paulo using CDC traps baited with dry ice between 2011 and 2013, yielding a total of 223 specimens. Six SSR primers were successfully transferred to Cx. nigripalpus yielding satisfactory results for allele richness, ranging from 5 to 12 alleles per locus. The expected heterozygosity values were higher than the observed heterozygosity (P < 0.05) for the loci CxqCTG10, CxqGT51, and Cxpq59. Linkage disequilibrium results were statistically significant only for the comparison between the loci CxqCA115 and CxqCTG10, and the estimation for the probability of null alleles was also low, ranging from 0 to 0.052.These results substantially validate the SSRs transference to Cx. nigripalpus as well as their subsequent use in microevolution studies comprising this species.
Canine babesiosis is an emerging tick-borne disease with a worldwide distribution, including Malaysia. While the prevalence of Babesia has been documented from dogs in Malaysia, occurrence of Babesia has been relatively little studied in their tick vectors. Accordingly, a total of 240 dogs and 140 Rhipicephalus sanguineus sensu lato (s.l.) (Acari: Ixodidae) ticks from Malaysia were molecularly screened for the presence of Babesia protozoa in the present study. Babesia gibsoni was only detected in ticks (1.4%), whereas Babesia vogeli was detected in both ticks (1.4%) and dogs (2.1%). This study highlights the detection of B. gibsoni and B. vogeli for the first time, in both adult and nymphal stages of R. sanguineus s.l. in Malaysia, suggesting the potential role of this tick species in transmitting canine babesiosis.
The mosquito fauna of Iowa has been extensively investigated over several decades, providing a wealth of information regarding species distributions, relative abundance, temporal activity patterns, and identifying vectors of medical importance. However, these investigations have had unequal coverage, leaving the mosquito fauna in some parts of the state, including southern Iowa, largely uncharacterized. With the heightened public health threat of Zika virus in the summer of 2016, greater emphasis was placed on surveying for two potential Zika virus vectors: Aedes (Stegomyia) albopictus (Skuse) and Aedes (Stegomyia) aegypti (Linnaeus). Southern Iowa became an area of interest due to the range of Ae. Albopictus, potentially extending into this part of the state. Employing CO2-baited Centers for Disease Control and Prevention light traps and BG-Sentinel traps, our targeted trapping efforts in southern Iowa did not yield either Ae. albopictus or Ae. aegypti. However, the geographical expansion of our trapping efforts did lend valuable insights into the mosquito fauna of southern Iowa. Mosquito species such as Aedes atropalpus (Coquillett), Culex erraticus (Dyar and Knab), and several Psorophora species once presumed rare or uncommon in the state were found to be more prevalent in this ecologically diverse region, augmenting our understanding of mosquito distributions in the state. Moreover, these surveillance efforts established baseline data for continued monitoring of the potential introduction and spread of invasive mosquito species in Iowa as part of an integrated mosquito management program
Hepatozoon canis has been widely reported in dogs. Its prevalence in ticks, however, has not been well-established. Here we determine the occurrence of Hepatozoon DNA in the brown dog tick Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) sensu lato (s.l.) and domestic dogs from Peninsular Malaysia using a polymerase chain reaction (PCR) assay based on amplification of the 18S ribosomal RNA coding sequence. Our results revealed a relatively low prevalence of H. canis DNA in both R. sanguineus s.l. (0.7%) and dogs (3.33%). This study represents the first report of H. canis DNA in R. sanguineus s.l. in Malaysia, highlighting the risk of this infection in dogs.
Leishmaniasis is a vector-borne disease caused by the protozoan Leishmania and it is one of the six most important infectious diseases in the world.The aim of this study was to conduct a research on the fauna and most frequented ecotopes by sandflies on islands of the Paraná River. The sandflies were collected with Falcão light traps in 10 islands in the municipalities of São Pedro do Paraná, Porto Rico, and Querência do Norte, in Paraná State, Brazil, from November 2012 to November 2014. In total, 76,145 specimens of Nyssomyia neivai, the only species found, were collected, of which 63,015 were female and 13,130, male.The largest number of sandflies was collected mainly in domiciles and peridomiciles.The islands of the Paraná River showed predominance of Ny. neivai, which is largely involved in the transmission of Leishmania and a risk of human leishmaniasis to the island inhabitants and tourists.
Wolbachia is a genus of endosymbiotic bacteria that infects 66% of all insect species. Its major impact on insects is in reproduction: sterility, production of one sex, and/or parthenogenesis. Another effect was discovered when the disease-transmitting mosquito, Aedes aegypti Linnaeus (Diptera: Culicidae), was infected with Wolbachia isolated from Drosophila: infected female mosquitoes became less capable of transmitting diseases such as dengue fever and chikungunya. This has led to releases of Ae. aegypti carrying Wolbachia in an attempt to control disease. An open question is whether there are natural Wolbachia infections of this mosquito. We assayed DNA from 2,663 Ae. aegypti from 27 countries on six continents, 230 from laboratory strains, and 72 Aedes mascarensis MacGregor (Diptera: Culicidae) for presence of Wolbachia DNA. Within the limits of our polymerase chain reaction–based assay, we found no evidence of Wolbachia, suggesting that natural infections of this endosymbiont are unlikely to occur throughout the worldwide distribution of Ae. aegypti.
Our species have altered their surroundings since its early dispersion on Earth. Unfortunately, thanks to human-modified habitats, several pest organisms such as domiciliary insects have expanded their distributions. Moreover, pest-related microorganisms may also be aided by anthropization. Pest cockroaches are globally distributed and capable of carrying several diseases. We explored if urbanization may buffer environmental conditions allowing pest insects to expand their distribution. Specifically, we suggest that human settlements may generate suitable microhabitats for synanthropic cockroaches, helping them to survive and establish with disregard to overall climatic restrictions.To test this idea we studied the distribution of pest cockroaches spanning the length of Chilean territory. Chile, along its 4270 km length north to south extent, is a country offering a formidable sampling of Earth's climatic diversity accompanied by dense urbanizations. We studied entomological collections and spatially analyzed pest cockroach distribution found in Chile and discovered that synanthropic cockroach populations are consistently concentrated near most urban developed zones of the country and not limited by overall temperature. Furthermore, health-concern pest cockroach species were widely distributed in Chilean territory, found even in its most southern urban centers as well as Easter Island. Therefore, these disease vectors could exist even in isolated and extreme climatic zones as long as urbanization provides the adequate microhabitat. We discuss the need for further research in order to assess if these distributions can be extrapolated to the pathogenic strains these pest insects may be carrying as reported in other regions of the planet.
Bagrada hilaris is an invasive stink bug present in Asia, Africa, Europe, North America, and recently found in Chile, South America. Painted bug is well known as an agricultural pest, attacking mostly Brassicaceae. First records of the painted bug B. hilaris invading homes are given from Chile, from the Metropolitan, and Valparaiso Regions, including mild and heavily infested homes. In addition, the first case ever of an adventitious bite in a human being by this species is provided and described. Additionally, first alleged cases of occupational allergy are also mentioned. The possible reasons of the occurrence of these invasions are commented and discussed. It is concluded that the invasions may be due because of the lack of food plant sources in nearby wild and agroecosystems; forcing the bugs to migrate to closely located cities. As a result, it is recommended to extend education and control programs from agricultural to urban residential areas.
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