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Disease vectoring mosquitoes are a serious threat to humans. However, till today only few mosquito repellents have been identified. The current study was conducted to evaluate the repellent potential of Carpesium abrotanoides essential oil against Aedes aegypti females by human bait technique. Essential oil was extracted by steam distillation process while the identification of chemical constituents was carried out by gas chromatography–mass spectrometry. Time span repellent bioassays of C. abrotanoides essential oil in comparison to DEET were performed at three different doses (33 µg/cm2, 165 µg/cm2, and 330 µg/cm2) under laboratory conditions. Highest repellency periods for essential oil and DEET were observed at the tested dose of 330 µg/cm2 with 315 min and 720 min, respectively. Lowest repellency period of 45 min for essential oil and 105 min for DEET was recorded at the tested dose of 33 µg/cm2. Major constituents caryophyllene (24.3%) and trans-nerolidol (12.0%) of C. abrotanoides essential oil were also evaluated as repellents at three different doses (330 µg/cm2, 165 µg/cm2, and 33 µg/cm2) against Ae. aegypti. Surprisingly, trans-nerolidol completely inhibited Ae. aegypti landings for 45 min when tested at 330 µg/cm2. However, caryophyllene did not completely inhibit Ae. aegypti landing even after immediate application at the tested dose of 330 µg/cm2. At the tested dose of 330 µg/cm2, the mixture (trans-nerolidol + caryophyllene) completely inhibited Ae. aegypti landing for 60 min indicating the synergistic effect of caryophyllene. Hence, C. abrotanoides as well as its major constituent, especially trans-nerolidol, have potential to formulate as mosquito repellent comparable of DEET.
Many flies of Diptera are common entomological evidence employed in forensic investigation. Exploring the existence of inter- and intra-species genomic differences of forensically relevant insects is of great importance. Aldrichina grahami is a common blow fly species of forensic importance. The present study characterized the gene repertoires of A. grahami, and provides insights into issues related to forensic entomology, such as necrophagous behavior, gene family features, and developmental patterns. Gene families were clustered and classified according to their function in different aspects of the necrophagous lifestyle, generating several gene repertoires. The genes under positive selection pressure and evolutionary changes were screen and identified. Moreover, genes that exhibited potential prediction value in the post mortem interval (PMI) estimation and development of immature stages were subjected to analysis based on the developmental transcriptome. Related insect species were compared at the genomic level to reveal the genes associated with necrophagous behaviors. The expression of selected genes in separated repositories was verified using qPCR. This work was conducted using a high-quality chromosome-level genome assembly of A. grahami and its developmental transcriptome. The findings will facilitate future research on A. grahami and the other forensically important species.
The flesh fly Sarcophaga ruficornis (Fabricius) is one of the fly species of significant medical and forensic importance since it is one of the most common flesh flies used in forensic investigations. Zolpidem tartrate is a sedative-hypnotic drug used for the short-term treatment of insomnia in adults and its use has been implicated in many suicide cases worldwide. Fresh chopped liver of buffalo Bubalus bubalis (Artiodactyla: Bovidae) containing different concentrations of Zolpidem tartrate was given to S. ruficornis larvae to evaluate the effect of Zolpidem tartrate on the developmental rate of the different stages, life cycle duration, and the morphological parameters. The findings have shown significant variation in the time required for the different developmental stages and total life cycle duration, which correlated positively with the Zolpidem tartrate concentration in different cultures. Compared to the control, the morphological parameters were negatively correlated with the concentration of Zolpidem tartrate in the treated cultures. The obtained results indicate that the Zolpidem tartrate retards larval development and alters the estimation of the total developmental duration. Thus, when Zolpidem tartrate may be the cause of death, the entomological evidence needs to be analyzed so it takes zolpidem-related changes to the mPMI into account.
Malathion is a widely used organophosphorus pesticide; it is also a molecule of forensic interest due to its moderate to high toxicity in nontarget organisms, humans included. This compound is present in some fatal intoxications, accidental or intentional; its presence in the tissues on which the cadaveric entomofauna feeds may affect its growth rate and life cycle duration leading to an error in the estimation of the minimum postmortem interval (PMImin). Since the toxic effect of malathion on the cadaveric entomofauna could affect the estimation of the PMImin, the aim of this work was to study the toxic effect of malathion on the growth and development of the scuttle fly, Megaselia scalaris, a fly of forensic interest which plays an important role in forensics cases related to human remains found indoors or in concealed environments. The study was complemented with some morphological observations; no morphological changes were observed in the larvae, nor the adult flies exposed to malathion. Malathion affects the viability of the egg and pupa, it also reduces the larval growth rate and increases the duration of the larval stage; therefore, the estimation of the PMImin, with this species when malathion is present in tissues, could be affected.
The female, pupa, and fourth-instar larva of Culex (Melanoconion) aliciae are described for the first time, and the male is redescribed. The cibarium, female and male genitalia, pupa, and fourth-instar larva are illustrated. Information on distribution, bionomics, and taxonomy is also included. Males of Cx. aliciae Duret and Cx. martinezi Casal & Garcia are indistinguishable, except for the appearance of the ninth tergal lobes. The female of Culex martinezi has not been described before. The females of Culex aliciae can be recognized by characteristics of the occipital scales, cibarium, and genitalia. The larva of Cx. aliciae and Cx. martinezi can be distinguished from characters of the thorax and abdomen.
Environmental conditions associated with urbanization are likely to influence the composition and abundance of mosquito (Diptera, Culicidae) assemblages through effects on juvenile stages, with important consequences for human disease risk. We present six years (2011–2016) of weekly juvenile mosquito data from distributed standardized ovitraps and evaluate how variation in impervious cover and temperature affect the composition and abundance of container-breeding mosquito species in Maryland, USA. Species richness and evenness were lowest at sites with high impervious cover (>60% in 100-m buffer). However, peak diversity was recorded at sites with intermediate impervious cover (28–35%). Four species were observed at all sites, including two recent invasives (Aedes albopictus Skuse, Ae. japonicus Theobald), an established resident (Culex pipiens L), and one native (Cx. restuansTheobald). All four are viral vectors in zoonotic or human transmission cycles. Temperature was a positive predictor of weekly larval abundance during the growing season for each species, as well as a positive predictor of rapid pupal development. Despite being observed at all sites, each species responded differently to impervious cover. Abundance of Ae. albopictus larvae was positively associated with impervious cover, emphasizing that this medically-important vector not only persists in the warmer, impervious urban landscape but is positively associated with it. Positive temperature effects in our models of larval abundance and pupae occurrence in container habitats suggest that these four vector species are likely to continue to be present and abundant in temperate cities under future temperature scenarios.
Sand flies (Diptera: Psychodidae) transmit several Leishmania (Kinetoplastida: Trypanosomatidae) species, which cause leishmaniasis, a significant public health concern in Algeria. We compared sand fly species abundance and composition among different biotopes (urban, peri-urban, rural areas), bioclimatic zones (humid, sub-humid, semi-arid), and elevation ranges. We also used the additive partitioning of beta diversity to test whether the variation in sand fly composition among biotopes, bioclimatic zones, and elevation ranges is due to species turnover or community subsetting. In total, 7,478 specimens were captured; of which, 7,162 (51.5% males vs. 48.5% females) belong to eight species: Phlebotomus perniciosus Newstead, 1911 (77.4% of the total captured specimens), Phlebotomus perfiliewi Parrot, 1930 (14.6%), Phlebotomus longicuspis Nitzulescu, 1911 (5.9%), Phlebotomus papatasi Scopoli, 1786 (<1%), Phlebotomus sergenti Parrot, 1917 (<1%) and Phlebotomus chadlii Rioux, Juminer et Gibily 1966 (<1%), Sergentomyia minuta Adler et Theodor, 1927 (1%), and Sergentomyia fallax Parrot, 1921 (<1%). Sand fly total abundance showed negative correlations with altitude and was significantly higher in rural areas. Sandfly community composition was significantly different between rural and urban/peri-urban areas. The additive partitioning of beta diversity showed that 71.4% of the compositional dissimilarity among elevation ranges and bioclimates was due to sand fly species turnover, and 28.6% resulted from nestedness. However, the variation in sand fly composition among different biotopes was mainly due to community nestedness. Findings from this study help define the risk of Leishmania transmission and develop methods for vector control in Mila province and Algeria as a whole.
Aedes albopictus is one of the main mosquito vectors responsible for transmitting arboviruses to humans and animals. The ability of this mosquito to support virus transmission has been linked to vector competence, which is partly attributed to the genetic disparities in Ae. albopictus population. At present, little is known about the biologically important traits of Ae. albopictus in Malaysia. Thus, the study aims to determine the genetic variation of Ae. albopictus based on the mitochondria-encoded sequences of cytochrome oxidase subunit I (COI). A statistical parsimony network of 253 taxa aligned as 321 characters of the COI gene revealed 42 haplotypes (H1–H42), of which H1 was the most widespread haplotype in Peninsular Malaysia. Three highly divergent haplotypes (H21, H30, and H31) were detected from the northern population. Overall, haplotype and nucleotide diversities were 0.576 and 0.003, respectively, with low genetic differentiation (FST = 0.039) and high gene flow (Nm = 12.21) across all populations.
Mackenzie Tietjen, Adalberto A. Pérez de León, Agustin Sagel, Steve R. Skoda, Pamela L. Phillips, Robert D. Mitchell III, Joanne Caruth, Uziel Durán, Lisa Musai, Silvia Tortosa, Alex P. Arp
The New World screwworm, Cochliomyia hominivorax (Coquerel 1858) (Diptera: Calliphoridae), is a serious parasite of livestock, humans, and other warm-blooded animals. It has been eradicated from the northern parts of its historical range down to the Panama—Colombian border where a permanent barrier zone is maintained. This eradication was accomplished through using the sterile insect technique (SIT). In 2016 there was an outbreak of C. hominivorax in the Florida Keys. In only six months, this pest was successfully re-eradicated using SIT, but the geographic origin of the invasion has yet to be resolved. It was previously determined that the Florida flies most likely represented a single invasion, and it was recommended that a finer-scale genetic assessment should be completed. Thus, this current proof-of-concept study aimed to develop a population genetic database using single nucleotide polymorphisms (SNPs) to reference outbreaks and potentially identify the origin of the Florida outbreak. This initial database consists of wild-caught samples from 4 geographic locations as well as laboratory colony samples that originated from 7 additional locations using a genotyping by sequencing (GBS) approach. Geographic population structuring was identified for twelve populations that clustered according to geographic location. The Florida outbreak samples appeared similar to samples from the outer Caribbean cluster which included samples from Dominican Republic and Trinidad and Tobago, however, these results will be further clarified with the replacement of laboratory colony samples with future wild-caught samples.
Allan Kardec R. Galardo, Andréa V. Hijjar, Liliane Leite O. Falcão, Dario P. Carvalho, Kaio Augusto N. Ribeiro, Guilherme A. Silveira, Noel Fernandes S. Neto, José F. Saraiva
Mansonia (Diptera: Culicidae) are known to cause discomfort to the local populations of Amazon. Considering the fact that the effective control of these mosquitoes can only be obtained by understanding their ecology and behavior, entomological monitoring becomes essential. In view of this, mosquitoes of the genus Mansonia were collected by human landing catches (HLC) from 2015 to 2019, in four locations of Porto Velho, Rondônia, Brazil. The collections were performed inside and outside the homes, once in every four months, uninterrupted for 24 hr. Human bite indices/hour was used to analyze the hourly activity of the species for different seasons and environment (indoor and outdoor). Moreover, nonparametric Mann–Whitney tests were conducted to indicate if there were differences between exophagic and endophagic behavior. The seasonality of Mansonia species was also analyzed. Overall, 96,766 specimens were collected over five years of sampling. Mansonia titillans (Walker) was found to be the most abundant species (76.9%). The highest percentage of mosquitoes was collected in February (48.4%), followed by October (39.6%) and June (12.0%). The biting activity of the two most abundant species showed peak host seeking activity/behavior during twilight and night, more perceptible in the outdoor environment (peridomiciliary). In general, seasonality showed a tendency towards a reduction in the abundance of Mansonia in the years after 2015. Our results will be essential in the formulation of effective control methodology for Mansonia in the studied area.
Efficacies of essential oils (EOs) of Vetiveria zizanioides (L.) Nash. (Poales: Poaceae) (VZ EO), Cananga odorata (Lam) Hook. F. & Thomson (Magnoliales: Annonaceae) (CO EO), and crude extract (CE) of Andrographis paniculata (Burm.F.) Wall ex. Nees (Lamiales: Acanthaceae) (AP CE), against laboratory (lab) and field strains of Culex quinquefasciatus Say were investigated. Irritant and repellent activities of individual and binary mixtures of plant extracts were compared with N,N-diethyl-m-toluamide (DEET) using an excito-repellency system. The irritant activity (direct tarsal contact), the mean percent escape response of VZ EO (91.67%, 83.33%), and CO EO (80%, 88.33%) were not significantly different compared with DEET (88.33%, 95%) against lab and field strains, respectively. Similarly, irritant responses in combinations (1:1 and 1:2, v:v) of either VZ EO or CO EO with AP CE were not significantly different from DEET against both strains (P > 0.001). The repellent activity (no tarsal contact), the mean percent escape response of VZ EO (68.33%), CO EO (61.67%), and VZ EO+AP CE (1:1, v:v) (81.67%) against lab strain and CO EO (85%) against field strain were not significantly different from that of DEET (P > 0.001). Interestingly, the greatest contact irritancy of VZ EO+AP CE (1:1, v:v) (96.67%) (P = 0.0026) and a stronger repellency response of CO EO (85%) (P = 0.0055) produced significantly different patterns of escape response compared with DEET against both lab and field strains, respectively. The EOs of VZ EO and CO EO or their mixture with AP CE showed potential as plant-based active ingredients for mosquito repellents. In addition, the major chemical constituents of VZ EO were β-vetivone (6.4%), khusimol (2.96%), and α-vetivone (2.94%) by gas chromatograpy–mass spectrometry.
The control of medically important container-inhabiting mosquitoes is an ongoing challenge for mosquito control operations. Truck-mounted application equipment is a common option for rapid areawide larvicide deployment utilized by mosquito control operations. We tested the effectiveness of two truck-mounted sprayers (A1 Super Duty + Buffalo Turbine CSM3), for the deployment of water-dispersible biopesticides (VectoBac WDG:VectoLex WDG 50:50). Sixty residences within four residential neighborhoods in New Jersey were treated in 2019 and 2020. Three empty bioassay cups were placed in specific locations on each property (front yard/back yard/side of house), with an additional cup placed in an adjacent catch basin. This approach was replicated in two untreated control neighborhoods. Following larvicide application, cups were subjected to bioassays wherein larval mortality was tracked through adult eclosion. Overall, average larval mortality rates were 56% higher in treated cups compared against untreated controls. Mortality rates were affected by cup location, with 39% mortality in bioassay cups from back yards, 54% in those from the sides of houses, 73% in front yards, and 76% from cups in catch basins. Mortality did not differ significantly between the four treated neighborhoods, nor by the type of sprayer used. Our research shows that truck-mounted sprayers can be an effective method for larvicide deployment in residential neighborhoods, but effectiveness may depend upon the location of the target treatment area in relation to residences and other geographic obstacles.
Neeta P. Connally, Adam Rowe, Alison Kaufman, James I. Meek, Sara A. Niesobecki, Amberjean P. Hansen, Jennifer White, Courtney Nawrocki, Erik Foster, Alison F. Hinckley, Lars Eisen
Blacklegged ticks, Ixodes scapularis Say, transmit Lyme disease spirochetes and other human pathogens in the eastern United States. White-tailed deer (Odocoileus virginianus) are key reproductive hosts for I. scapularis adults, and therefore control methods targeting deer have the potential for landscape-wide tick suppression. A topical acaricide product, containing 10% permethrin, is self-applied by deer to kill parasitizing ticks when they visit 4-Poster Tick Control Deer Feeders (hereafter, 4-Posters) Previous 4-Poster intervention studies, including in residential settings, demonstrated suppression of I. scapularis populations but did not include human-based outcomes. To prepare for a proposed 4-Poster intervention trial in residential areas of Connecticut and New York that would include human-tick encounters and tick-borne diseases as outcomes, we sought to identify areas (study clusters) in the 80–100 ha size range and specific locations within these areas where 4-Poster devices could be deployed at adequate density (1 device per 20–25 ha) and in accordance with regulatory requirements. Geographic Information System-based data were used to identify prospective study clusters, based on minimum thresholds for Lyme disease incidence, population density, and forest cover. Ground truthing of potential 4-Poster placement locations was done to confirm the suitability of selected clusters. Based on these efforts, we failed to identify more than a few residential areas fulfilling all criteria for a treatment cluster. We, therefore, reconsidered pursuing the intervention trial, which required inclusion of >30 treatment clusters to achieve adequate statistical power. The 4-Poster methodology may be more readily evaluated in natural or public areas than in residential settings in NY or CT.
Amblyomma americanum Linnaeus (Ixodida: Ixodidae) is ubiquitously present throughout the southeastern United States and is capable of vectoring several pathogens. White-tailed deer are the main host for adult A. americanum. However, this tick species is a generalist that will feed on most vertebrates, including humans, deer, livestock, and pets. Management of this species can be challenging due to a lack of cost-effective strategies. Acaricides are often utilized, however, this may lead to pesticide resistance. The Food and Agriculture Organization of the United Nations (FAO) larval packet test (LPT) was performed on susceptible A. americanum to determine the lethal concentration (LC) and discriminating concentration (DC) values for permethrin. The FAO LPT was used at these pre-established values to compare levels of resistance in ticks collected from a captive deer farm and wild areas representing high and low permethrin exposure settings, respectively. Resistance ratios (RR) calculated from the LC values for the ticks collected from farmed and wild deer ranged between 1 and 2. A. americanum collected from farmed and wild deer were not found to be resistant, however, some samples had slightly elevated RRs as compared to the susceptible laboratory strain, which may suggest tolerance development. Although the A. americanum sampled in this study were not resistant to permethrin, the DC calculated in this study will allow for rapid evaluation of resistance in a permethrin resistance monitoring program such that alternate management strategies can be adopted if resistance is detected.
Francisco J. Gonzalez-Santillan, Yamili Contreras-Perera, Jesus A. Davila-Barboza, Alan E. Juache-Villagrana, Selene M. Gutierrez-Rodriguez, Gustavo Ponce-Garcia, Beatriz Lopez-Monroy, Iram P. Rodriguez-Sanchez, Audrey E. Lenhart, Lucy Mackenzie-Impoinvil, Adriana E. Flores
In Mexico, Aedes aegypti (L.) is the primary dengue vector, chikungunya, and Zika viruses. The continued use of synthetic pyrethroids has led to the development of resistance in target populations, which has diminished the effectiveness of vector control programs. Resistance has been associated with disadvantages that affect the biological parameters of resistant mosquitoes compared to susceptible ones. In the present study, the disadvantages were evaluated by parameters related to survival and reproduction (‘fitness cost’) after selection with deltamethrin for five generations. The parameters analyzed were the length of the development cycle, sex ratio, survival, longevity, fecundity, egg viability, preoviposition, oviposition and postoviposition periods, and growth parameters. In the deltamethrin-selected strain, there was a decrease in the development cycle duration, the percentage of pupae, the oviposition period, and eggs viability. Although mean daily fecundity was not affected after the selection process, this, together with the decrease in the survival and fecundity levels by specific age, significantly affected the gross reproductive rate (GRR), net reproductive rate (Ro), and intrinsic growth rate (rm) of the group selected for five generations with deltamethrin compared to the group without selection. Identifying the ‘cost’ of resistance in biological fitness represents an advantage if it is desired to limit the spread of resistant populations since the fitness cost is the less likely that resistant individuals will spread in the population. This represents an important factor to consider in designing integrated vector management programs.
Pests are frequently found in homes, especially in apartment buildings in low-income communities. We investigated the prevalence and patterns of pest infestations in low-income communities in four cities (Jersey City, Linden, Paterson, Trenton) in New Jersey, USA. Resident interviews, visual inspections, and the placement of monitors were used to identify pest infestations. A total of 1,753 apartments from 19 buildings or building complexes were accessed. The infestation rates of cockroaches, bed bugs (Cimex lectularius L.), and house mice (Mus musculus domesticus Schwarz and Schwarz) were 37, 9, and 20%, respectively. Among apartments with cockroaches, 97.8, 2.5, and 0.8% had German cockroach [Blattella germanica (L.)], American cockroach [Periplaneta americana (L.)], and Oriental cockroach (Blatta orientalis L.), respectively. The percentage of residents who were aware of the presence of cockroaches, bed bugs, and house mice was 70.8, 55.3, and 56.8%, respectively. The prevalence of pest infestation was associated with resident ethnicity and gender. Among 856 interview responses, 78% implemented methods themselves to control pests in their homes in the past six months. Chocolate spread detected 99% of house mouse infestations and was much more sensitive than three commercial blank baits. Significant differences were also observed in the feeding preference of the three commercial blank baits.
Casimir Dossou Kpanou, Hermann W. Sagbohan, Arthur Sovi, Razaki Osse, Gil G. Padonou, Albert Salako, Filémon Tokponnon, Arsène Jacques Fassinou, Boulais Yovogan, Udoka C. Nwangwu, Constantin J. Adoha, Esdras Mahoutin Odjo, Idelphonse Ahogni, Aboubakar Sidick, Lamine Saïd Baba-Moussa, Martin Akogbéto
Pyrethroid resistance is widespread in sub-Saharan Africa. The objective of this study was to assess the insecticide resistance intensity in Anopheles gambiae s.l. (Diptera: Culicidae) in four districts of Benin in order to better understand how pyrethroid-only nets are likely to be effective. Thus, adult females of An. gambiae s.l., reared from field-collected larvae were used for assessing resistance intensity to permethrin and deltamethrin. They were tested at 1×, 5×, and 10× the diagnostic dose, using both WHO susceptibility tube testing and CDC bottle bioassays. Identification of molecular species, as well as of L1014F Kdr and Ace-1R mutations was performed using the PCR. The level of expression of biochemical enzymes was also evaluated. Overall, moderate to high resistance intensity to permethrin and deltamethrin was observed, irrespective of the testing method. While the L1014F Kdr frequency was high (>75%), Ace-1R was low (≤6%) in An. gambiaes.s. and Anopheles coluzzii, the two predominant species [52% (95% CI: 44.8–59.1) and 45% (95% CI: 38.0–52.2), respectively]. Anopheles arabiensis was found at very low frequency (3%, 95%CI: 1.1–6.4). For Biochemical analyses, α and β-esterases were over-expressed in all four districts, while mixed-function oxidases (MFOs) were over-expressed in only one. Overall, the two testing methods led to comparable conclusions, though there were a few inconsistencies between them. The moderate-high resistance intensity observed in the study area suggests that dual active-ingredient (AI) long-lasting insecticidal nets (LLINs) may provide better control of insecticide-resistant mosquitoes.
Urbanization alters components of natural ecosystems which can affect tick abundance and tick-borne disease prevalence. Likely due to these changes, tick-borne pathogen prevalence has increased in many U.S. urban areas. Despite the growing public health importance of tick-borne diseases, little is known about how they are influenced by urbanization in North America, especially in the central U.S. where several pathogens occur at or near their highest levels of incidence nationally. To determine whether urban development influences tick infection with bacteria and protozoa, we collected ticks at 16 parks across a gradient of urbanization intensity in Oklahoma City, Oklahoma, USA and tested them using a variety of PCR assays. Adult ticks tested positive for Rickettsia parkeri, R. amblyommatis, R. rhiphicephali, ‘Candidatus R. andeanae’, Ehrlichia chaffeensis, E. ewingii, Panola Mountain Ehrlichia, ‘Borrelia lonestari’, Theileria cervi, Babesia spp. Coco, and Cytauxzoon felis. These results indicate the presence of a high diversity of tick-borne bacteria and protozoa across an expanding urban area in the U.S. Great Plains. Although there appeared to be some risk of encountering tick-borne microorganisms across the entire urbanization gradient, E. chaffeensis, E. ewingii, and T. cerviinfected ticks and microbe diversity decreased with increasing urbanization intensity. We identified a low rate of coinfection between different microorganisms, with coinfected ticks mainly collected from sites in the least-urbanized areas. This study suggests the need for awareness of tick-borne disease risk throughout urban areas in the central U.S., and highlights a need for studies of tick host habitat use and movement in cities.
We tested two versions of a trap that captures climbing ticks on their dorsum. A prototype based on a decades old model had three components, a truncated pyramidal base with steep sloping walls, downward facing sticky-tape extending beyond and spanning the boundary of the flat upper surface, on which ticks become dorsally immobilized, and a reservoir for gaseous CO2 emission from dry ice that rests on the flat upper surface. A preoperational trap was made of thermoformed plastic and differed from the prototype by its circular structure, a central depression suitable for future housing of a biotic CO2 generator and supplemental volatile lures and a transparent sticky ceiling that enables ticks to exhibit a phototactic response and allows users to see captured ticks without disturbing the traps. Field testing of the prototype in Florida and both trap types in Oklahoma and North Carolina achieved high catches of lone star ticks, Amblyomma americanum (L.) (Acari: Ixodidae), e.g. mean catches of >70 ticks (adults plus nymphs) in 4 h in both the prototype and preoperational traps in North Carolina, and significantly higher yields of ticks than on dry ice baited 1 m2 white sheets.
Ixodes pacificus Cooley & Kohls is the primary vector of Lyme disease spirochetes to humans in the western United States. Although not native to Alaska, this tick species has recently been found on domestic animals in the state. Ixodes pacificus has a known native range within the western contiguous United States and southwest Canada; therefore, it is not clear if introduced individuals can successfully survive and reproduce in the high-latitude climate of Alaska. To identify areas of suitable habitat within Alaska for I. pacificus, we used model parameters from two existing sets of ensemble habitat distribution models calibrated in the contiguous United States. To match the model input covariates, we calculated climatic and land cover covariates for the present (1980–2014) and future (2070–2100) climatologies in Alaska. The present-day habitat suitability maps suggest that the climate and land cover in Southeast Alaska and portions of Southcentral Alaska could support the establishment of I. pacificus populations. Future forecasts suggest an increase in suitable habitat with considerable uncertainty for many areas of the state. Repeated introductions of this non-native tick to Alaska increase the likelihood that resident populations could become established.
Hormozgan Province is one of the important foci of malaria in Iran. In addition to malaria pathogens, mosquitoes also transmit the pathogens that cause dirofilariasis and West Nile fever in the province. Also, the threat of emerging aedine-borne viruses that cause infections, such as Chikungunya, dengue, and Zika, is noticeable. There is little information about the fauna and bionomics of Culicinae in the province. The present investigation aimed to study the fauna, diversity, and bionomics of culicines. The study was conducted from September 2016 to April 2017 in four counties of Bandar Abbas, Bandar Khamir, Bashagard, and Jask. In total, 3,236 larvae and 1,901 adults including 16 culicine species were collected. The larvae of Culiseta longiareolata (Macquart) (25.65%), Culex pipiens Linnaeus (16.62%), and Cx. quinquefasciatus Say (16.16%) were most abundant and Cx. hortensis Ficalbi (0.09%) was least abundant. Among adults, Cx. laticinctus Edwards (33.19%), Cx. quinquefasciatus (31.09%), and Cx. pipiens (11.99%) were the most prevalent species and Cs. longiareolata (0.47%), Aedes caballus (Theobald) (0.90%), and Cx. bitaeniorhynchus Giles (0.90%) were the least prevalent species. The pairwise similarities of fauna of the counties and different collecting methods and diversity indices were investigated. More ecological data, especially on host preference, seasonality, and larval habitat characteristics, are needed as a basic knowledge for any intervention measures using integrated vector management.
Wagner de Souza Fernandes, Jucelei de Oliveira Moura Infran, Everton Falcão de Oliveira, Aline Etelvina Casaril, Suellem Petilim Gomes Barrios, Samuel Lucas Lopes de Oliveira, Alessandra Gutierrez de Oliveira
The presence, abundance, and distribution of sandflies are strongly influenced by climate and environmental changes. This study aimed to describe the sandfly fauna in an intense transmission area for visceral leishmaniasis and to evaluate the association between the abundance of Lutzomyia longipalpis sensu lato (Lutz & Neiva 1912) (Diptera: Psychodidae) and climatic variables. Captures were carried out 2 yr (July 2017 to June 2019) with automatic light traps in 16 sites of the urban area of Campo Grande, Mato Grosso do Sul state. The temperature (°C), relative humidity (%), precipitation (mm3), and wind speed (km/h) were obtained by a public domain database. TheWilcoxon test compared the absolute frequencies of the species by sex. The association between climatic variables and the absolute frequency of Lu. longipalpis s.l. was assessed using the Spearman's correlation coefficient. A total of 1,572 sandflies into four species were captured. Lutzomyia longipalpis s.l. was the most abundant species and presented a significant correlation with the average temperature, humidity, and wind speed in different periods. Lutzomyia longipalpis s.l. was captured in all months, showing its plasticity in diverse weather conditions.We emphasize the importance of regular monitoring of vectors and human and canine cases, providing data for surveillance and control actions to continue to be carried out in the municipality.
Dengue Hemorrhagic Fever (DHF) is a major mosquito-borne viral disease. Studies have reported a strong correlation between weather, the abundance of Aedes aegypti, the vector of DHF virus, and dengue incidence. However, this conclusion has been based on the general climate pattern of wide regions. In general, however, the human population, level of infrastructure, and land-use change in rural and urban areas often produce localized climate patterns that may influence the interaction between climate, vector abundance, and dengue incidence. Thoroughly understanding this correlation will allow the development of a customized and precise local early warning system. To achieve this purpose, we conducted a cohort study, during January-December 2017, in 16 districts in Bandung, West Java, Indonesia. In the selected areas, local weather stations and modified light mosquito traps were set up to obtain data regarding daily weather and the abundance of adult female Ae. aegypti. A generalized linear model was applied to analyze the effect of local weather and female adult Ae. aegypti on the number of dengue cases. The result showed a significant non-linear correlation among mosquito abundance, maximum temperature, and dengue cases. Using our model, the data showed that the addition of a single adult Ae. aegypti mosquito increased the risk of dengue infection by 1.8%, while increasing the maximum temperature by one degree decreased the risk by 17%. This finding suggests specific actionable insights needed to supplement existing mosquito eradication programs.
El Hadji Ibrahima Ndiaye, Georges Diatta, Adama Zan Diarra, Jean Michel Berenger, Hubert Bassene, Oleg Mediannikov, Charles Bouganali, Cheikh Sokhna, Philippe Parola
Bed bugs are known to carry several microorganisms. The purpose of this study was to assess the prevalence of bed bug infestation in two rural areas of Senegal and determine the species present in the population. A screening was conducted to detect some arthropod associated pathogenic bacteria in bed bugs and to evaluate the prevalence of endosymbiont carriage. One survey took place in 17 villages in Niakhar and two surveys in Dielmo and Ndiop and surroundings area in the same 20 villages. Bed bugs collected were identified morphologically and by MALDI-TOF MS tools. Microorganisms screening was performed by qPCR and confirmed by sequencing. During the survey in the Niakhar region, only one household 1/255 (0.4%) in the village of Ngayokhem was found infested by bed bugs. In a monitoring survey of the surroundings of Dielmo and Ndiop area, high prevalence was found during the two rounds of surveys in 65/314 (21%) in 16/20 villages (January–March) and 93/351 (26%) in 19/20 villages (December). All bed bugs were morphologically identified as the species Cimex hemipterus, of which 285/1,637 (17%) were randomly selected for MALDI-TOF MS analysis and bacteria screening. Among the Bacteria tested only Wolbachia (Alphaproteobacteria, Rickettsiales, Rickettsiaceae) DNA was found in 248/276 (90%) of the bedbugs. We briefly describe a high level of non-generalized bed bug infestation in rural Senegal and the diversity of Wolbachia strains carried by C. hemipterus. This study opens perspectives for raising household awareness of bed bug infestations and possibilities for appropriate control.
Tick-borne diseases are an increasing concern for people and companion animals in the United States, but there is a need for continued vigilance regarding livestock in pasture systems. The south-central United States has some of the highest incidences of tick-borne diseases, and there is a need to re-examine the ecology of tick vectors in relation to pasture systems and livestock. The objective of this study was to establish a baseline of seasonal activity for tick species in diverse regional Oklahoma pastures and screen for important pathogens in Dermacentor variabilis (Say) and Amblyomma maculatum Koch group that may impact livestock and human health. Between 2015 and 2017, transects in five pastures across Oklahoma were visited each month. DNA extracted from adult D. variabilis and A. maculatum group was tested for the presence of bacterial pathogens. We found that tick communities in pastures across Oklahoma differ by season, abundance, and bacterial presence and prevalence. The peak abundance of Amblyomma americanum (L.) adults and nymphs occurred a month earlier over the 2 yr of the study compared with historical studies in the same regions. Additionally, we observed notable differences in peak activity between A. americanum adults and nymphs collected in pastures in central Oklahoma (April) versus pastures in northern part of the state (May). We detected Rickettsia parkeri, R. bellii, and Anaplasma sp. DNA in D. variabilis from pastures across the state. These results potentially have important ramifications for human and livestock risk of encountering infected ticks in pastures across the southern Great Plains.
For several years, there have been continuous reports of black flies in Mississippi with evidence of transmission of Leucocytozoon spp. This study was conducted to determine the presence and diversity of Leucocytozoon spp. in black flies captured throughout Mississippi. Thirty-three collections, consisting of 346 specimens, were made during the 2-yr period (2015–2016) at 10 locations around the state. In addition to these systematic biweekly collections, 46 specimens were taken in 10 collections at four additional sites from 2009 to 2014, as well as 388 specimens taken in 14 collections during a severe black fly outbreak during March and April of 2018. Out of 186 pooled samples, 21 samples were positive for haemosporidian DNA. Eighteen of those samples were identified as Leucocytozoon spp. A phylogenetic tree was constructed using the novel sequences along with existing sequences from the MalAvi database. Results showed several of the sequences constructed in this study had high divergence from the existing sequences from the database.
Ratawan Ubalee, Heung-Chul Kim, Siriporn Phasomkusolsil, Jaruwan Tawong, Ratree Takhampunya, Amnart Kayha, Suparat Chairuksa, Waranya Buadok, Vichit Phunkitchar, Betty K. Poole-Smith, Silas A. Davidson, Won-Ja Lee, Terry A. Klein
There are eight Anopheles spp. present in the Republic of Korea (ROK), including five members of the Anopheles Hyrcanus Group that cannot be identified using current morphological methods. The vector competence of only Anopheles sinensis s.s., An. lesteri, and An. kleini have been investigated. As the geographical distribution of Anopheles spp. varies in the ROK, determining the relative vector competence of the Anopheles spp. provides a basis for delineating malaria risks to Korean populations and U.S. military/civilian populations deployed to the ROK. Anopheles belenrae and An. pullus, collected from a malaria high-risk area in the ROK, were evaluated for vector competence of P. vivax. A total of 1,000 each of An. dirus (Thai strain), and Korean strains of An. pullus and An. belenrae were fed on P. vivax infected blood collected from Thai patients via artificial membrane feeding. The overall oocyst infection rates for An. dirus, An. pullus, and An. belenrae dissected on days 8–9 postfeed were 64.1, 12.0, and 11.6%, respectively. The overall sporozoite infection rates for those species dissected on days 14–15 postfeed were 84.5, 3.4, and 5.1% respectively. The salivary gland sporozoite indices for positive females with +4 (>1,000 sporozoites) were observed in An. dirus (72.8%), but not observed for either An. pullus or An. belenrae. Most sporozoite-positive An. pullus (83.3%) and An. belenrae (71.4%) females were observed with only +1 (1–10 sporozoites) salivary glands. These data indicate that both An. belenrae and An. pullus are very poor vectors of P. vivax.
Prairie dogs in the western United States experience periodic epizootics of plague, caused by the flea-borne bacterial pathogen Yersinia pestis. An early study indicated that Oropsylla hirsuta (Baker), often the most abundant prairie dog flea vector of plague, seldom transmits Y. pestis by the classic blocked flea mechanism. More recently, an alternative early-phase mode of transmission has been proposed as the driving force behind prairie dog epizootics. In this study, using the same flea infection protocol used previously to evaluate early-phase transmission, we assessed the vector competence of O. hirsuta for both modes of transmission. Proventricular blockage was evident during the first two weeks after infection and transmission during this time was at least as efficient as early-phase transmission 2 d after infection. Thus, both modes of transmission likely contribute to plague epizootics in prairie dogs.
Precise identification of anopheline species is paramount for incrimination of malaria vectors and implementation of a sustainable control program. Anopheline mosquitoes are routinely identified morphologically, a technique that is time-consuming, needs high level of expertise, and prone to misidentifications especially when considering Amazonian species. The aim of this study was therefore to develop a DNA-based identification technique to supplement traditional morphological identification methods for the discrimination of anopheline mosquitoes collected in French Guiana. The internal transcribed spacer 2 (ITS2) region of ribosomal DNA (rDNA) for anopheline species was amplified by polymerase chain reaction (PCR), and digested with AluI/MspI restriction enzymes. PCR-restriction fragments length polymorphism (RFLP) assay was compared to sequencing of the ITS2 region for validation. Fifteen Anopheles species have shown distinct PCR-RFLP profiles. A concordance of 100% was obtained when identification by PCR-RFLP was compared to sequencing of ITS2. A high throughput, fast, and cost-effective PCR-RFLP assay has been developed for unambiguous discrimination of fifteen anopheline mosquito species from French Guiana including primary and suspected secondary malaria vectors.
Raquel Lima de Souza, Gabriel dos Santos Ferreira, Lairton Souza Borja, Romero de Jesus Nazaré, Vánio Andre Mugabe, Hernan Darío Argibay, Moyra Machado Portilho, Leile Camila Jacob-Nascimento, Mitermayer Galvão Reis, Uriel D. Kitron, Guilherme Sousa Ribeiro
We identified mosquito species (Diptera: Culicidae) in an Atlantic Forest fragment located in a large urban park in Salvador, Brazil, one year after a citywide epizootic of yellow fever virus (YFV). Between May 2 and August 2, 2018, adult mosquitoes were collected using the human attraction method, followed by trapping with hand-nets, and CO2-baited light traps placed at ground level and in the canopy. We collected a total of 11,914 mosquitoes, which belonged to three tribes, five genera, and at least seven species. The most abundant taxa captured by CO2-baited light traps were Culex quinquefasciatus (Say, Diptera: Culicidae) Limatus spp. (Diptera: Culicidae), and Wyeomyia spp. (Diptera: Culicidae), while by human attraction, Cx. quinquefasciatus, Wyeomyia spp., and Aedes albopictus (Skuse, Diptera: Culicidae) were captured most often. The diversity of mosquitoes by species was greater in the park area with restinga vegetation compared to the area with dense rainforest. Although vectors commonly associated with sylvatic YFV transmission were not captured, we collected several species capable of transmission of other arboviruses. Given the high likelihood of encounters between mosquitoes and human visitors in environments, such as the one studied, periodic entomological surveys to determine the risk of arbovirus transmission in these settings are warranted.
Ornithoica aequisenta Maa 1966 (Diptera: Hippoboscidae) is recorded for the first time from a rodent from China. An updated checklist of louse flies including 21 genera and 52 species of Hippoboscoidea (Hippoboscidae, Nycteribiidae, and Streblidae) is presented for mainland China and Taiwan, including collection records and host species.
Maggot debridement therapy (MDT) is a therapy with the medical use of sterile fly larvae of certain species, particularly those within the Calliphoridae family including green bottle fly, Lucilia sericata (Meigan, Diptera: Calliphoridae), for treating chronically infected wounds and ulcers. Lucilia sericata flies were maintained under insectary conditions, and the eggs were sterilized using three treatments: hydrogen peroxide solutions, used as a hand disinfectant (Treatment 1—T1), hydrogen peroxide, surface disinfectant (Treatment 2—T2), and SaniHigene (Treatment 3—T3) and the control (without treatment). All three treatment caused the complete sterilization of eggs, and no bacterial colonies were found on the blood agar culture. The egg hatching rate after 72 h was much higher than after 24 h. Egg mortality in hydrogen peroxide solutions, T1 and T2, was 3–4% and less than in solution T3 (13%). Owing to less mortality and more sterility of the eggs, the aforementioned solutions are suggested to be appropriate for sterility in maggot therapy.
Bed bugs are hematophagous insects with a long history of presence in human communities. Over the last three decades, infestations by bed bugs in human dwellings have drastically increased, leading to a rise in bed bug concerns. This study was conducted in May 2019 in the Miarinarivo district of Madagascar. Eight locations with suspected infestations were inspected. Of these, five locations were found with active bed bug infestations. Overall, 23 (19 adults and four nymphs) specimens with numbers per apartment ranging from 2 to 6 were collected and analyzed using morphological and molecular approaches. Of 19 adults collected, 18 were morphologically identified as Cimex hemipterus (Hemiptera: Cimicidae), with the final adult identified as C. lectularius. Morphological identification of adults was confirmed by sequencing 450 bp fragment of COI gene. All four nymphs were also identified molecularly as C. hemipterus. Maximum likelihood phylogenetic tree of COI gene and sequence alignment of C. hemipterus specimens revealed the presence of two groups (first group clustered with previously reported haplotype from Asian and African countries and the second group encompassed a lesser known haplotype exclusively from Africa (Kenya and Senegal). This study presents low genetic diversity among C. hemipterus specimens and, for the first time, reports the occurrence of C. lectularius, known as temperate species, in Madagascar. These results can be helpful in control management strategies against these ectoparasites in this country.
The genus Latrodectus contains the most medically important spiders around the world. This study describes the first case of Latrodectus cinctus Blackwall, 1865 bite and clinical treatment from Iran. Also, it is the first collection report from the southeast of the country that can enhance prior knowledge on the geographical distribution of this species. We describe a 42-year-old female patient with neurological pain caused by the spider bite. Also, a summary of the entomological survey and morphological identification of the collected species from the patient's house is presented.
Aedes albopictus (Skuse) is native to Southeast Asia and has colonized tropical and temperate regions worldwide in the last three to four decades. In Africa, data on its distribution is incomplete. Most studies having focused on the abundance, competition to other species, and phylogenetics of this vector are from the central African region. Here, we report the first detection of Ae. albopictus in Benin, West Africa. A total of 13 specimens were collected during the study period in 2021. The phylogenetic analysis of a cytochrome oxidase c subunit I gene fragment revealed a close relationship to populations from tropical India. Because of its close geographical proximity to areas where it has been found, it is assumed that the species was introduced several years before and is currently widely distributed in Benin. Additional studies are needed to explore its distribution, expansion range, and competitive effects on native species.
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