Vector control is an important component of the interventions aimed at mosquito-borne disease control. Current and future mosquito control strategies are likely to rely largely on the understanding of the behavior of the vector, by exploiting mosquito biology and behavior, while using cost-effective, carefully timed larvicidal and high-impact, low-volume adulticidal applications. Here we review the knowledge on the ecology of mosquito oviposition behavior with emphasis on the potential role of infochemicals in surveillance and control of mosquito-borne diseases. A search of PubMed, Embase, Web of Science, Global Health Archive, and Google Scholar databases was conducted using the keywords mosquito, infochemical, pheromone, kairomone, allomone, synomone, apneumone, attractant, host-seeking, and oviposition. Articles in English from 1974 to 2019 were reviewed to gain comprehensive understanding of current knowledge on infochemicals in mosquito resource-searching behavior. Oviposition of many mosquito species is mediated by infochemicals that comprise pheromones, kairomones, synomones, allomones, and apneumones. The novel putative infochemicals that mediate oviposition in the mosquito subfamilies Anophelinae and Culicinae were identified. The role of infochemicals in surveillance and control of these and other mosquito tribes is discussed with respect to origin of the chemical cues and how these affect gravid mosquitoes. Oviposition attractants and deterrents can potentially be used for manipulation of mosquito behavior by making protected resources unsuitable for mosquitoes (push) while luring them towards attractive sources (pull). In this review, strategies of targeting breeding sites with environmentally friendly larvicides with the aim to develop appropriate trap-and-kill techniques are discussed.

Aedes aegypti (L.) (Diptera: Culicidae) is an important vector of viruses causing dengue, Zika, chikungunya, and yellow fever and as such is a threat to public health worldwide. Effective trapping methods are essential for surveillance of both mosquito species and disease presence. The Centers for Disease Control Miniature Light Trap (CDC-MLT) is an updated version of the New Jersey light trap, which was developed early in the 20^th century. This trap is widely reported as being less successful for Ae. aegypti than for other mosquito species, although the reason for this is unclear. This trap has engendered more Ae. aegypti-tailored designs that still represent the basic design model. The efficiency of the CDC-MLT alone and with CO₂ was tested under semi-field conditions and the behavior of responding female Ae. aegypti was characterized. The CDC-MLT alone failed to capture any mosquitoes and with CO₂ the capture efficiency was less than 2%. Understanding the behaviors that mosquitoes exhibit while encountering a particular trap design or trapping concept may suggest trap improvements to increase capture efficiency. Moreover, this work contributes to our understanding of mosquito host-seeking behavior.

Most mosquito species are active during a certain part of the day, but climatic factors such as light intensity and relative humidity play an important role in the control of their activity. We selected three types of land use that were sampled in state of Campeche in 2018 (low semi-evergreen forest, secondary low semi-evergreen forest, and mango plantation), using ten CDC light traps baited with CO₂, that were active during nine hours of three activity periods (dawn, noon, and nightfall). A GLM was used to investigate changes in the assembly of mosquitoes between different types of land use and temporal variations. Rank abundance curves were used to detect changes in the spatial and activity period of the mosquitoes and we then calculated the Exponential Shannon Index. A total of 6,110 mosquitoes belonging to 23 species were captured. The greatest richness and abundance were found in the secondary low semi-evergreen forest, with greater richness and lower abundance than the mango plantation which showed more abundance. Of the activity periods, dusk had the greatest abundance and richness followed by dawn and finally noon.

Mosquitoes have developed specialized oviposition strategies that allow them to develop in a wide variety of aquatic habitats. Environmentally cued hatching traits may also play an important role in the successful colonization of some larval habitats, but this subject has remained largely unexplored in Culicidae. Aedes atropalpus (Coquillett) is an autogenous rock pool specialist that may maintain unique adaptations for oviposition and egg hatching. We investigated the egg-laying strategies of Ae. atropalpus exposed to standard (non-diapausing) rearing conditions and diapause-inducing conditions and tested the impact of physical agitation on egg hatch rates by exposing floating and submerged eggs to physical agitation treatments. The results of the oviposition experiment indicate that Ae. atropalpus females primarily lay non-diapausing eggs directly onto the water surface and lay diapausing eggs directly on solid surfaces. The egg-hatching experiment demonstrated that physical agitation significantly increases Ae. atropalpus hatch rates. Floating and submerged eggs responded similarly to the agitation treatment. These data suggest that oviposition behaviors based on both egg diapause status and environmentally-cued hatching strategies may be important adaptations for Ae. atropalpus in riverine rock pools.

Resistance to pyrethroids (PY) and organophosphate (OP) insecticides is widespread among populations of Culex quinquefasciatus, the major vector of lymphatic filariasis (LF). The present study was designed to detect the L1014F kdr (knockdown resistant) mutation among Cx. quinquefasciatus populations in the filarial belt of Sri Lanka. Mosquitoes were reared from field-caught larvae from seven localities where LF is endemic. Susceptibility status of Cx. quinquefasciatus to adulticides, 0.05% deltamethrin, 0.75% permethrin, 5% malathion, and the larvicide temephos was determined using the standard WHO susceptibility tests. A fragment of vgsc gene was amplified and sequenced to identify the responsible kdr mutations. The susceptibility test results revealed less than 90% mortalities for 0.05% deltamethrin, and 0.75% permethrin and temephos. For 5% malathion, all study sites except Maharagama revealed greater than 90% mortality. The L1014F kdr mutation was observed in all studied populations. Although the overall microfilaria rate is less than 1% in the country, there is a high risk of re-emergence of LF in Sri Lanka due to abundant Cx. quinquefasciatus mosquitoes, increased resistant status to currently used insecticides, imported LF cases, higher rates of microfilaria among neighboring countries, and the advancement of tourism.

The objectives of this study were to investigate the prevalence and abundance of deer keds on various cervids in Lithuania, to molecularly characterize the deer ked species based on mitochondrial COI and 16S rRNA genes, and to compare them with Lipoptena species found in other countries. A total of 11,939 deer keds (Lipoptena cervi and Lipoptena fortisetosa) was collected from the fur of 30 cervids in Lithuania between 2015 and 2019. The values of infestation with deer keds differed among the species of the hosts. Moose and red deer were more frequently infested with L. cervi than with L. fortisetosa, while L. fortisetosa was found more often on roe deer. Phylogenetic analysis of the COI and 16S rRNA genes of five Lipoptena species revealed 110 and 55 variable nucleotide positions, respectively. Among Lithuanian samples, three COI haplotypes of L. cervi and three haplotypes of L. fortisetosa were detected, while there was no variation observed in the 16S rRNA sequences analyzed with one haplotype of L. cervi and one haplotype of L. fortisetosa. This is the first study on L. cervi and L. fortisetosa parasitizing cervids and the first molecular characterization of these deer ked species in Lithuania.

Due to their high solubility and stability, neonicotinoid insecticides are able to accumulate in water bodies, affecting aquatic organisms. The aims of this study were to evaluate resistance (LC₅₀) of Anopheles messeae s.l. (Anopheles messeae and An. daciae) to the neonicotinoid imidacloprid and to search for genetic markers associated with insecticide resistance. The LC₅₀ values of these species in the collections during 2017 and 2018 were indistinguishable and were in the range of 0.027-0.051 mg/l. In general, the LC₅₀ values of the mosquitoes were comparable with values of other mosquito species of the Anopheles and Culex genera. Gene polymorphisms of the variations in intron lengths and the presence of restriction sites in introns that were potentially associated with the metabolism of insecticides were studied. Polymorphisms of the studied genes in the pair of closely related species considered overlapped, but allele frequencies were different. Part of the genetic variants arose due to insertions of repetitive elements of the genome. Two variants of the cytochrome P450 gene Cyp6AG1 in An. daciae were associated with increased resistance to imidacloprid. Possible side effects of selection on insecticide resistance in blood-sucking mosquitoes are discussed. Journal of Vector Ecology 45 (2): 220-232. 2020.

The cat flea Ctenocephalides felis is the main vector of Bartonella henselae and Bartonella clarridgeiae, the causative agents of cat-scratch disease (CSD) and the spotted-fever agent Rickettsia felis. In spite of their worldwide distribution, there are no data on the occurrence of CSD-causing Bartonella species or the prevalence of Rickettsia species in the Canary Islands, Spain. Therefore, the aim of our study was to screen cat and dog fleas for both pathogens. A total of 128 C. felis from cats and dogs were screened for Bartonella and Rickettsia by PCR. Bartonella henselae (2.3%) and B. clarridgeiae (3.9%) were found in fleas infesting cats, whereas R. felis was identified in both cat (36.6%) and dog (40.7%) fleas. Further, co-infections were observed. This work constitutes the first finding of CSD-causing Bartonella species and the first study on the prevalence of R. felis in fleas from domestic animals in the Canary Islands. These results indicate public health importance, as associated infections could be misdiagnosed in the Archipelago despite their clinical relevance. Establishing human and animal routine diagnosis procedures for these pathogens along with improving vector control in shelters is necessary in order to prevent the spread of the infections among animals.

The objective of this study was to investigate evidence of emerging anaplasmosis and bartonellosis in rodents from endemic areas of Nakhon Ratchasima, Thailand. Rodent trapping was undertaken in 13 sub-districts of Muang District. The live-capture traps were set up in three locations of selected scrub typhus patient houses for three consecutive nights. Wild-caught rodent whole blood samples and associated ticks and fleas were collected and tested for Anaplasma spp. and Bartonella spp. In addition, heat maps using GIS software were used to determine the density of infection of positive wild-caught rodents. A total of 347 wild-caught rodents of nine species was captured. Rattus rattus (38.6%) was the dominant species. A total of 1,518 Heamaphysalis bandicota ticks and 57 Xenopsylla cheopis fleas was removed. Twenty-two of the 347 tested blood samples (6.3%) were Anaplasma bovis-positive and 121 blood samples and five out of 27 pools of X. cheopis fleas were Bartonella queenslandensis-positive. Of these infected rodents, dual-infections between A. bovis and B. queenslandensis were found in three B. indica rodents. Our results offer new information concerning the infections of A. bovis and B. queenslandensis in both rodents and their ectoparasites collected in high-risk areas of rodent-borne diseases in Thailand.

Because isolated ecosystems contribute to species variability, especially oceanic island ecosystems, the present work focused on the study of the Bartonella species and haplotypes in Lanzarote and El Hierro, two Canary islands with evident bioclimatic differences between them. A total of 123 rodents and 110 fleas from two islands were screened for the presence of Bartonella by PCR analysis of the gltA and nuoG genes. The overall prevalence was 5.7% in rodents and 20.4% in fleas. A total of seven gltA-haplotypes was found in both rodents and fleas, belonging to the species Bartonella mastomydis and Bartonella tribocorum in Lanzarote, and to Bartonella rochalimae and Bartonella elizabethae in El Hierro, as well as recently described species Bartonella kosoyi in both islands. Besides, potential co-infections were detected based on the nuoG analysis. Further, Xenopsylla cheopis was the only flea species identified. Our study shows that isolated ecosystems such as the Canary Islands lead to the appearance of new Bartonella haplotypes along different biotopes, with diverse flea species involved in the spreading of the pathogen being of great relevance due to the zoonotic potential of the species found.

Tabanids and stable flies are important nuisances to livestock and sometimes humans. Nzi, Vavoua, and Biconical traps or insecticide-impregnated blue screens are commonly used to attract and catch these flies. Such devices are made of a specific cotton or cotton-polyester phthalogen blue fabric acting as a visual attractant. However, the cost of cotton fabrics is high, and they are no longer available due to toxic dyes. The present study compared four blue polyester fabrics produced in Thailand with a reference blue cotton-polyester fabric made in France by TDV^® to attract hematophagous flies. Vavoua traps and blue screens covered with a sticky film made with the five different blue fabrics were compared. The TDV^® had the highest trapping scores; however, there was no significant difference between TDV^® and some polyester fabrics. Among the tested polyester fabrics, CR Solon No.41 was nearly as effective as the TDV^® in attracting biting flies. The mean attractivity indices of CR Solon No.41, NS No.1469, Globe 2000 No.21, Globe 2000 No.34 were 0.86, 0.79, 0.69, and 0.39, respectively. Thus, we recommend that CR Solon No.41 would be the appropriate fabric for the further development of low-cost and optimized screens and traps in Thailand and other countries.

Through their potentially devastating impacts on the environment, wildfires may impact pathogen, vector, and host interactions, leading to changing risks of vector-borne disease in humans and other animals. Despite established risks for tick-borne disease and increasing frequency and severity of wildfires in the United States, impacts of wildfire on ticks and tick-borne pathogens are understudied. In 2015, the large Wragg fire extensively burned a long-term field site at Stebbins Cold Canyon University of California Reserve (CC). We characterized the tick, reservoir host and pathogen community over a two-year period after the burn, comparing our findings to pre-fire data and to data from Quail Ridge Reserve (QR), a nearby unburned site. After the fire, there were 5.5 times more rodent, primarily Peromyscus spp., captures at CC than QR (compared to 3.5 times more pre-fire). There were significantly fewer dusky-footed woodrats (Neotoma fuscipes) at both sites post-fire, likely due to drought but not fire. Pre-fire tick infestation prevalence on rodents was comparable across sites (12.5% at CC and 9.9% at QR) and remained low at CC post-fire (13.7%) but was significantly higher at QR (48.0%), suggesting that ticks or their habitat were destroyed during the burn. Normalized difference vegetation indices documented a 16-fold loss of vegetation post-compared to pre-fire at CC; loss of vegetation and direct impacts on fauna are likely the main drivers of the post-fire differences in ticks we saw at CC. These data contribute to our understanding of tick-associated disease risks in our increasingly disturbed landscapes.

Aedes japonicus japonicus (Theobald) is a relatively recent immigrant to the Pacific Northwest, having been collected in Washington State in 2001 and in British Columbia (BC) since 2014. We applied a molecular barcoding approach to determine the phylogenetic relationship of Ae. j. japonicus populations in BC with those from around the world. We sequenced a 617 base-pair segment of the cytochrome c oxidase 1 gene and a 330 base-pair region of the NADH dehydrogenase 4 gene to find genetic variation and characterize phylogenetic and haplotypic relationships based on nucleotide divergences. Our results revealed low genetic diversity in the BC samples, suggesting that these populations arose from the same introduction event. However, our approach lacked the granularity to identify the exact country of origin of the Ae. j. japonicus collected in BC. Future efforts should focus on detecting and preventing new Ae. j. japonicus introductions, recognizing that current molecular techniques are unable to pin-point the precise source of an introduction.

Mucins, the main structural components of vertebrate respiratory, digestive and reproductive tract mucus, as well as insect peritrophic matrix, play important roles in protecting host cells from invading microbes and difficult external environments. Mucins are characterized by highly glycosylated proteins constituting the mucin domain that is rich in repetitive sequences of threonine, serine, and proline (PTS). Despite potential important roles, mosquito mucins remain largely uncharacterized. Here, we performed bioinformatics analyses to identify proteins with PTS repeat domain and predicted 43 mucins or mucin-related proteins in Aedes albopictus. Gene expression analysis revealed that these mucins are dynamically expressed across different development stages and in different organs of Aedes albopictus. Of note, blood feeding upregulated AALF016448 and AALF013291 expression in the midgut, fat body, and ovary, raising the possibility that these mucins play potential roles in reproduction, digestion, and intestinal defense against invading pathogens upon blood feeding. Our in silico identification, followed by expressional validation, thus established a valuable resource for further dissecting the functions of mucins for vector control.

We present the first records of Anopheles (Anopheles) plumbeus Stephens, 1828 and Culex (Culex) torrentium Martini, 1925 in the autonomous region of Galicia (NW Spain), obtained through the Rede Galega de Vixilancia de Vectores (ReGaViVec). This entomological surveillance network, which was initiated in 2017 by the Xunta de Galicia in collaboration with the University of Vigo and the University of Santiago de Compostela, aims to detect the arrival of invasive vectors as well as to improve the knowledge about mosquito populations (Diptera: Culicidae) in the Galician territory. This study shows the first findings of these species in Galicia, which have been reported in six different locations throughout the region: five in the province of Pontevedra and one in the province of Lugo. The 51 captured specimens were collected at different stages of development between July and September, 2018 and 2019 by using specialized traps arranged in favorable regions for the settlement and development of culicids.

The mosquito Aedes albopictus is a vector of several arboviruses transmitted to humans. They have a sylvatic behavior, occurring in rural areas. However, reports of their adaptation to anthropic environments have been increasing. The aim of this study is to investigate the presence and distribution of Ae. albopictus in the Metropolitan Region of Belém in the Brazilian Amazon and evaluate its preference for either natural or artificial breeding sites under the weather conditions of the Amazon. Ovitraps (artificial breeding sites) and bamboo internodes (natural breeding sites) were deployed in neighborhood peridomiciles during the dry and rainy seasons. The results showed that the presence of Ae. albopictus was recorded in 71.4% of the neighborhoods during the dry season and in 69.2% neighborhoods during the rainy season, thus indicating a wide distribution in the region. A significant increase in the frequency of the capture of mosquitoes in areas with higher vegetation cover was observed during the dry season (R²= 0.2995; p=0.018) but not during the rainy season (R²= 0.044; p=0.43). Comparing the weekly frequency of Ae. albopictus on positive bamboos and OVT, no significant difference was observed between them (t= 0.559; df= 23; p=0.58). A significant increase in the number of positive breeding sites was observed with increased rainfall for both bamboo (R²= 0.33; p= 0.002) and OVT (R²= 0.24; p= 0.013). This is the first report of Ae. albopictus in the metropolitan area of Belém. The findings suggest a wide distribution in the studied area, preferably in areas with more extensive vegetation cover. Additionally, the mosquito population showed the ability to use both natural and artificial habitats.

Due to climate change-induced alterations of temperature and humidity, the distribution of pathogen-carrying organisms such as ticks may shift. Tick survival is often limited by environmental factors such as dryness, but a predicted hotter and wetter world may allow the expansion of tick ranges. Dermacentor andersoni and D. variabilis ticks are morphologically similar, co-occur throughout the Inland Northwest of Washington State, U.S.A., and both can be injected with pathogenic Rickettsia and Francisella bacteria. Differences in behavior and the potential role of endosymbiotic Rickettsia and Francisella in these ticks are poorly studied. We wanted to measure behavioral and ecological differences between the two species and determine which, if any, Rickettsia and Francisella bacteria – pathogenic or endosymbiotic - they carried. Additionally, we wanted to determine if either tick species may be selected for if the climate in eastern Washington becomes wetter or dryer. We found that D. andersoni is more resistant to desiccation, but both species share similar questing behaviors such as climbing and attraction to bright light. Both also avoid the odor of eucalyptus and DEET but not permethrin. Although both tick species are capable of transmitting pathogenic species of Francisella and Rickettsia, which cause tularemia and Rocky Mountain Spotted Fever, respectively, we found primarily non-pathogenic endosymbiotic strains of Francisella and Rickettsia, and only one tick infected with F. tularensis subspecies holarctica.

Rattus rattus was first reported from the West Nile Region of Uganda in 1961, an event that preceded the appearance of the first documented human plague outbreak in 1970. We investigated how invasive R. rattus and native small mammal populations, as well as their fleas, have changed in recent decades. Over an 18-month period, a total of 2,959 small mammals were captured, sampled, and examined for fleas, resulting in the identification of 20 small mammal taxa that were hosts to 5,109 fleas (nine species). Over three-fourths (75.8%) of captured mammals belonged to four taxa: R. rattus, which predominated inside huts, and Arvicanthis niloticus, Mastomys sp., and Crocidura sp., which were more common outside huts. These mammals were hosts for 85.8% of fleas collected, including the efficient plague vectors Xenopsylla cheopis and X. brasiliensis, as well as likely enzootic vectors, Dinopsyllus lypusus and Ctenophthalmus bacopus. Flea loads on small mammals were higher in certain environments in villages with a recent history of plague compared to those that lacked such a history. The significance of these results is discussed in relation to historical data, the initial spread of plague in the WNR and the continuing threat posed by the disease.

Sylvatic plague, caused by the bacterium Yersinia pestis and transmitted by fleas, occurs in prairie dogs of the western United States. Outbreaks can devastate prairie dog communities, often causing nearly 100% mortality. Three competent flea vectors, prairie dog specialists Oropsylla hirsuta and O. tuberculata, and generalist Pulex simulans, are found on prairie dogs and in their burrows. Fleas are affected by climate, which varies across the range of black-tailed prairie dogs (Cynomys ludovicianus), but these effects may be ameliorated somewhat due to the burrowing habits of prairie dogs. Our goal was to assess how temperature and precipitation affect off-host flea abundance and whether relative flea abundance varied across the range of black-tailed prairie dogs. Flea abundance was measured by swabbing 300 prairie dog burrows at six widely distributed sites in early and late summer of 2016 and 2017. Relative abundance of flea species varied among sites and sampling sessions. Flea abundance and prevalence increased with monthly mean high temperature and declined with higher winter precipitation. Predicted climate change in North America will likely influence flea abundance and distribution, thereby impacting plague dynamics in prairie dog colonies.

Wing lengths of parous (P) and nulliparous (NP) PCR-identified female Anopheles belenrae, An. kleini, An. pullus, and An. sinensis were determined from weekly trap collections at Camp Humphreys (CH), Ganghwa Island (GH), and Warrior Base (WB), Republic of Korea (ROK) during Jun-Oct, 2009. Wing length was greatest at the beginning and end of the study period. Wing length of NPs tended to be less than that of Ps before the period of maximum greening (Jul-Aug) but greater thereafter. Larger specimens tended to be Ps, and weekly wing length of Ps appeared less variable than NPs, possibly due to selection. A bimodal wing length frequency distribution of An. sinensis suggested two forms comprising small- (≤4.5 mm, SW) and large-winged females (>4.5 mm, LW). LW comprised the majority of peaks in abundance, however %SW, while still a minority, often increased during these times suggesting a density-dependent effect. At WB and GH, a two to three-week periodicity in %SW was obvious for An. sinensis and An. kleini. Analyses of weather station and satellite data showed that smaller-winged An. sinensis were associated with warmer, more humid, and greener times of the year. SW and LW specimens possibly result from agricultural practices that are common across large areas; regular synchronous peaks of SW and LW were observed from different sites. Peaks in SW Ps followed peaks in NPs in a ‘ripple effect’ one to two weeks apart, suggesting that wing length combined with parity could be used to follow the emergence and survival of mosquito cohorts.