Journal of Vector Ecology最新文献

Aedes aegypti (L.) is a major vector of yellow fever, dengue, and Zika viruses, and its management can be difficult, especially in situations where insecticide usage is restricted and resistance is present. Traps and trapping techniques have mostly been used for monitoring populations of adult mosquitoes, but several commercially available traps have been evaluated and used to reduce nuisance populations of adult mosquitoes (Kline 2006). Suppression of Ae. aegypti, in particular, requires a suite of integrated control measures. One measure gaining more attention is to attract and kill gravid females by exploiting their oviposition behavior. Recently, a commercial larval trap for control of Culex mosquito larvae has been developed and marketed. The commercial brand name is My Mosquito Deleter (MMD; Destin, FL). When gravid female Culex mosquitoes lay their eggs in the MMD larval trap filled with water, the larvae after hatching from eggs will fall downward through the MMD's baffle system. The mosquito larvae cannot come to the surface due to the physical barrier from the baffle ring and black cone, resulting in larval mortality. During the preliminary experiment with the original MMD trap full of water, no adult mosquitoes were collected when larval mosquitoes were commonly recorded, because the gravid mosquitoes flew away after they laid their eggs. In order to catch gravid Aedes mosquitoes when they come to the trap to lay their eggs on water within the containers, we modified the MMD trap by placing sticky paper around the inside at the top of the trap (at the water line) after removing the baffle ring and lowering the water level to create an air pocket. The purpose of the study was to investigate the capability of a trap originally designed to trap Culex larvae to attract and kill gravid Ae. aegypti females with a simple and inexpensive modification by adding a piece of black sticky paper and lowering the level of water, in contrast to the unmodified MMD trap with a lower level of water.

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.

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.

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.

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.

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.

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.

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.