Abundance Of Cx Research Articles

The abundance of mosquito larvae in relation to associated microbiota and physicochemical parameters of marshland habitats in Kelaniya in Gampaha district of Sri Lanka

The abundance of mosquito larvae in relation to associated microbiota and physicochemical parameters of water in marshes from selected habitats in Kelaniya divisional secretariat area, of the Gampaha district, Sri Lanka were studied. Culex gelidus was found to be the dominant mosquito species found in marshes followed by Culex whitmorei, Culex tritaeniorhynchus, Culex quinquefasciatus, Culex fuscocephala, and Anopheles peytoni. Fourteen species/taxa of microbiota were identified. There was a significant positive correlation between the abundance of Cx. gelidus larvae and level of organic pollution in marshes as measured by the five-day Biological Oxygen Demand. A positive correlation for the presence of Cx. fuscocephala and Cx. gelidus in the marshland was also observed. Nevertheless, abundance of Cx. gelidus was negatively correlated with Cx. quinquefasciatus and Cx. whitmorei. The presence of Culex gelidus and Cx. tritaeniorhynchus were positively correlated with Daphnia magna indicating their co-existence in the same habitat requirement. Culex gelidus was negatively affected by the epibiont, Vorticella microstoma, when the latter organisms were present in higher densities. In contrast, the presence of Cx. whitmorei was positively influenced by the Vorticella microstoma, Difflugia corona, nauplius larva, and Keratella valga. There was a negative correlation between Cx. whitmorei and Monostyla bulla (Rotifera; Monogononta) and between the abundance of Cx. fuscocephala and Lecane luna in the same marshland. This study concludes that mosquito larvae and some microbiota are interdependent in marshlands. The level of abundance of mosquito larvae and microbiota varied with the level of water pollution. Cx. gelidus larvae are biologically affected by Vorticella microstoma. Many microbiota species compete with mosquito larvae for the same food items.

CULICINE MOSQUITOES (DIPTERA: CULICIDAE) COMMUNITIES AND THEIR RELATION TO PHYSICOCHEMICAL CHARACTERISTICS IN THREE BREEDING SITES IN EGYPT

Mosquitoes have diverse species and global distribution. Most freshwater bodies support different mosquito species breeding. The physicochemical characteristics of mosquito breeding sites may influence culicine species distribution and their abundance. This study aimed to determine culicine species communities and their abundance in two rural sites and one urban breeding site in Egypt considering physicochemical characteristics of breeding places. These areas were Al-Beshlawy drainage canal (Giza), El-Khartoum irrigation ditch (Beheira), and Tanta man-made ground hole (Gharbia), respectively. The measured physicochemical parameters were temperature, pH, salinity, turbidity, dissolved oxygen, and nitrite. Diversity indices (recorded number of species, diversity, equitability, and concentration of dominance) of mosquitoes were also calculated. The results showed that six culicine species were identified in the tested three breeding sites. These were Culex pipiens, Cx. univittatus, Cx. antennatus, Cx. quinqueifasciatus, Cx. perexiguus, and Culiseta longiareolata. All species are native to the Egyptian fauna. In all tested urban and rural breeding sites, Cx. pipiens was considered eudominant. Bray-Curtis dissimilarity in the culicine community between the tested sites ranged between 0.03 and 0.12. This dissimilarity may be attributed to the absence of certain species in some sites, as well as the significant difference in the abundance of Cx. pipiens and Cs. longiareolata among the sites. Water salinity and dissolved nitrite content differed significantly among the breeding sites. The multiple regression analysis between the identified culicine species and the physicochemical parameters showed that salinity, nitrite content, turbidity, and pH are considered key factors to predict some culicine species in water bodies.

CULICINE MOSQUITOES (DIPTERA: CULICIDAE) COMMUNITIES AND THEIR RELATION TO PHYSICOCHEMICAL CHARACTERISTICS IN THREE BREEDING SITES IN EGYPT

Mosquitoes have diverse species and global distribution. Most freshwater bodies support different mosquito species breeding. The physicochemical characteristics of mosquito breeding sites may influence culicine species distribution and their abundance. This study aimed to determine culicine species communities and their abundance in two rural sites and one urban breeding site in Egypt considering physicochemical characteristics of breeding places. These areas were Al-Beshlawy drainage canal (Giza), El-Khartoum irrigation ditch (Beheira), and Tanta man-made ground hole (Gharbia), respectively. The measured physicochemical parameters were temperature, pH, salinity, turbidity, dissolved oxygen, and nitrite. Diversity indices (recorded number of species, diversity, equitability, and concentration of dominance) of mosquitoes were also calculated. The results showed that six culicine species were identified in the tested three breeding sites. These were Culex pipiens, Cx. univittatus, Cx. antennatus, Cx. quinqueifasciatus, Cx. perexiguus, and Culiseta longiareolata. All species are native to the Egyptian fauna. In all tested urban and rural breeding sites, Cx. pipiens was considered eudominant. Bray-Curtis dissimilarity in the culicine community between the tested sites ranged between 0.03 and 0.12. This dissimilarity may be attributed to the absence of certain species in some sites, as well as the significant difference in the abundance of Cx. pipiens and Cs. longiareolata among the sites. Water salinity and dissolved nitrite content differed significantly among the breeding sites. The multiple regression analysis between the identified culicine species and the physicochemical parameters showed that salinity, nitrite content, turbidity, and pH are considered key factors to predict some culicine species in water bodies.

Patterns of Abundance, Host Use, and Everglades Virus Infection in Culex (Melanoconion) cedecei Mosquitoes, Florida, USA.

Everglades virus (EVEV), subtype II within the Venezuelan equine encephalitis (VEE) virus complex, is a mosquitoborne zoonotic pathogen endemic to south Florida, USA. EVEV infection in humans is considered rare, probably because of the sylvatic nature of the vector, the Culex (Melanoconion) cedecei mosquito. The introduction of Cx. panocossa, a tropical vector mosquito of VEE virus subtypes that inhabits urban areas, may increase human EVEV exposure. Field studies investigating spatial and temporal patterns of abundance, host use, and EVEV infection of Cx. cedecei mosquitoes in Everglades National Park found that vector abundance was dynamic across season and region. Rodents, particularly Sigmodon hispidus rats, were primary vertebrate hosts, constituting 77%–100% of Cx. cedecei blood meals. Humans were fed upon at several locations. We detected EVEV infection in Cx. cedecei mosquitoes in lower and upper regions of Everglades National Park only during the wet season, despite an abundance of Cx. cedecei mosquitoes at other sampling times.

Prevalence of Wuchereria bancrofti Infection in Mosquitoes from Pangani District, Northeastern Tanzania

Background: Wuchereria bancrofti is the most widely distributed of the 3 nematodes known to cause lymphatic filariasis, the other 2 being Brugia malayi and Brugia timori. Anopheles gambiae and Anopheles funestus are the main vectors. However, the relative contributions of mosquito vectors to disease burden and infectivity are becoming increasingly important in coastal East Africa, and this is particularly true in the urban and semiurban areas of Pangani District, Tanzania. Methods: Mosquitoes were sampled from 5 randomly selected villages of Pangani District, namely, Bweni, Madanga, Meka, Msaraza, and Pangani West. Sampling of mosquitoes was done using standard Centers for Disease Control light traps with incandescent light bulbs. The presence of W. bancrofti in mosquitoes was determined via polymerase chain reaction (PCR) assays using NV1 and NV2 primers, and PoolScreen 2 software was used to determine the estimated rate of W. bancrofti infection in mosquitoes. Results: A total of 951 mosquitoes were collected, of which 99.36% were Culex quinquefasciatus, 0.32% were Anopheles gambiae, and 0.32% other Culex species. The estimated rate of W. bancrofti infection among these mosquitoes was 3.3%. Conclusion: This was the first study employing the use of PoolScreen PCR to detect W. bancrofti circulating in mosquito vectors in Pangani District, northeastern Tanzania. The presence of W. bancrofti infection suggests the possibility of infected humans in the area. The high abundance of Cx. quinquefasciatus calls for integrated mosquito control interventions to minimise the risk of W. bancrofti transmission to humans. Further research is required to gain an in-depth understanding of the W. bancrofti larval stages in mosquitoes, their drug sensitivity and susceptibility profiles, and their fecundity.

Diversitas Nyamuk di Sekitar Kandang Ternak di Kecamatan Mantikulore Kota Palu

Mosquito transmitted diseases are still a health problem in Indonesia, including in Palu City. Among the types of mosquitoes as a vector of the disease, there are to be zoophilic of animal blood. The study against the diversity of mosquitoes has been conducted in the area with the largest cattle population in Palu City, that Mantikulore District. The purpose of this study was to gain an overview diversity of mosquitoes around the cattle sheds. The study was carried out with free collection of mosquitoes around cattle sheds from 18:00 to 06:00 and one light trapping (CDC-Light Trap) at each location throughout the night from 18:00 to 06:00. Distribution diversity of mosquito around cattle sheds in five locations obtained 3 genus and 14 species of mosquitoes from a total of 1,464 captured mosquitoes. Culex vishnui is the most abundant mosquito in four research sites, namely in Kawatuna (44.44%), Poboya (82.18%), Tondo (66.95%), and Tanamodindi (38.58%). While in Talise the most abundant mosquito is Cx. quinquefasciatus amount 52.39%. The abundance of Cx. quinquefasciatus and Cx. vishnui was directly proportional to the frequency and dominance index. Shannon-Wiener diversity index shows the level of diversity in Kawatuna village, Talise village, and Tanamodindi village belongs to the medium, and in Poboya village and Tondo village belongs to low.

Increased Adult Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae) Abundance in a Dengue Transmission Hotspot, Compared to a Coldspot, within Kaohsiung City, Taiwan.

The assumption that vector abundance differences might drive spatial and temporal heterogeneities in vector-borne disease transmission is common, though data supporting it is scarce. Here, we present data from two common mosquito species Aedes aegypti (Linnaeus) and Culex quinquefasciatus Say, biweekly sampled as adults, from March 2016 through December 2017, with BG-sentinel traps in two neighboring districts of Kaohsiung City (KC), Taiwan. One district has historically been a dengue transmission hotspot (Sanmin), and the other a coldspot (Nanzih). We collected a total 41,027 mosquitoes, and we found that average mosquito abundance (mean ± S.D.) was higher in Sanmin (Ae. aegypti: 9.03 ± 1.46; Cx. quinquefasciatus: 142.57 ± 14.38) than Nanzih (Ae. aegypti: 6.21 ± 0.47; Cx. quinquefasciatus: 63.37 ± 8.71) during the study period. In both districts, Ae. aegypti and Cx. quinquefasciatus population dynamics were sensitive to changes in temperature, the most platykurtic environmental variable at KC during the study period, a pattern predicted by Schmalhausen’s law, which states that organisms are more sensitive to small changes in environmental variables whose average value is more uncertain than its extremes. Our results also suggest that differences in Ae. aegypti abundance might be responsible for spatial differences in dengue transmission at KC. Our comparative approach, where we also observed a significant increment in the abundance of Cx. quinquefasciatus in the dengue transmission hotspot, suggests this area might be more likely to experience outbreaks of other vector borne diseases and should become a primary focus for vector surveillance and control.

Controlling Culex pipiens: antagonists are more efficient than a neonicotinoid insecticide.

Species vulnerability to pesticides depends on physiological sensitivity, the potential to recover, and the ecological context. We assessed the vulnerability of the mosquito Culex pipiens to a repeated treatment with thiacloprid in outdoor microcosms with and without antagonists (competitive and predatory invertebrates). Microcosms were treated repeatedly (three times) with thiacloprid at a concentration of 0.1, 1, or 10 µg/liter. In microcosms without antagonists, the abundance of Cx. pipiens larvae decreased moderately after the second and the third exposures to 10 µg/liter thiacloprid. In microcosms with antagonists, the abundance of Cx. pipiens larvae declined to approximately zero in the control group and the low concentration treatments during the five weeks of observation. By contrast, the abundance of Cx. pipiens larvae temporarily increased at 10 µg/liter thiacloprid after the second and third contamination. We explained this positive effect on the development of Cx. pipiens because of the decrease in competition due to the elimination of sensitive antagonists combined with the high recovery potential of Cx. pipiens. Based on these results, natural antagonists must be supported for the sustainable control of mosquitoes.

The mosquito fauna of the western region of Spain with emphasis on ecological factors and the characterization of Culex pipiens forms.

A total of 1,495 mosquitoes of 16 species was collected during 2012-2013, of which Cx. pipiens s.l. and Cx. theileri were the most abundant. Five new records for An. maculipennis s.s., Orthopodomyia pulcripalpis, Aedes (Ochlerotatus) punctor, Cx. europaeus, and Cx. modestus were found for this region. Cx. pipiens density varied across weather and habitat patterns, correlating positively with high temperatures and with a preference for urbanized areas and rural areas within a proximity of ovine farms. Moreover, molecular identification by CQ11FL was performed in 467 Cx. pipiens s.s., detecting both pipiens (66%) and molestus (8.4%) forms coexisting in different habitats (urban, peri-urban and rural) aboveground with a high degree of hybridization (25.7%). The abundance of Cx. pipiens in urban areas and farms, with the presence of hybrids, may increase their capacity to act as bridge vectors for the transmission of arboviral infections. These data will be helpful for further implementation of entomological programs focused on risk assessment for arboviruses or other mosquito-borne pathogens.

Influence of climatic factors on the abundance of Culex pipiens and Cx. quinquefasciatus (Diptera: Culicidae) adults in the Western Coast of Saudi Arabia

This study aims to examine the effect of weather factors, temperature (T), relative humidity (RH) and wind velocity (WV) on the abundance of <em>Cx</em>. (<em>Cux</em>.) <em>pipiens</em> L. and <em>Cx</em>. (<em>Cux</em>.) <em>quinquefasciatus</em>. Say, the two common and important mosquito species in the western coast of Saudi Arabia. The two species had the same ranges of T (15.00-30.00°C), RH (8.00-72.00%) and WV (0.10- 8.06 Km/h). <em>Cx. quinquefasciatus</em> had insignificantly (P˃0.05) lower means of the three factors than those of<em> Cx. pipiens.</em> Regression analysis indicated that abundance of <em>Cx. pipiens</em> and <em>Cx</em>. <em>quinquefasciatus</em> negatively related to T (regression coefficient, b=-0.06 and -0.01 for the two species, respectively) and WV (b=-0.40 and -0.16 for the two species, respectively) and positively related to RH (b=0.05 for both species). Such factors accounted for 81% and 76% of the variance in abundance of <em>Cx. pipiens</em> and <em>Cx. quinquefasciatus</em>, respectively while the remaining parts (19% and 24% for the two species, respectively) may be attributed to other factors mainly rainfall.

Seasonal abundance & role of predominant Japanese encephalitis vectors Culex tritaeniorhynchus & Cx. gelidus Theobald in Cuddalore district, Tamil Nadu.

Background & objectives:Japanese encephalitis (JE) is the leading cause of viral encephalitis in Asia. The first major JE outbreak occurred in 1978 and since 1981 several outbreaks had been reported in the Cuddalore district (erstwhile South Arcot), Tamil Nadu, India. Entomological monitoring was carried out during January 2010 - March 2013, to determine the seasonal abundance and transmission dynamics of the vectors of JE virus, with emphasis on the role of Culex tritaeniorhynchus and Cx. gelidus.Methods:Mosquito collections were carried out fortnightly during dusk hours in three villages viz. Soundara Solapuram, Pennadam, Erappavur of Cuddalore district. Mosquitoes were collected during dusk for a period of one hour in and around the cattle sheds using oral aspirator and torch light. The collected mosquitoes were later identified and pooled to detect JE virus (JEV) infection by enzyme linked immunosorbent assay (ELISA).Results:A total of 46,343 mosquitoes comprising of 25 species and six genera were collected. Species composition included viz, Cx. tritaeniorhynchus (46.26%), Cx. gelidus (43.12%) and other species (10.62%). A total of 17,678 specimens (403 pools) of Cx. gelidus and 14,358 specimens (309 pools) of Cx. tritaeniorhynchus were tested, of which 12 pools of Cx. gelidus and 14 pools of Cx. tritaeniorhynchus were positive for JE virus antigen. The climatic factors were negatively correlated with minimum infection rate (MIR) for both the species, except mean temperature (P<0.05) for Cx. gelidus.Interpretation & conclusions:High abundance of Cx. tritaeniorhynchus and Cx. gelidus was observed compared to other mosquito species in the study area. Detection of JEV antigen in the two species confirmed the maintenance of virus. Appropriate vector control measures need to be taken to reduce the vector abundance.

Statistical modeling of the abundance of vectors of West African Rift Valley fever in Barkédji, Senegal.

Rift Valley fever is an emerging mosquito-borne disease that represents a threat to human and animal health. The exophilic and exophagic behavior of the two main vector in West Africa (Aedes vexans and Culex poicilipes), adverse events post-vaccination, and lack of treatment, render ineffective the disease control. Therefore it is essential to develop an information system that facilitates decision-making and the implementation of adaptation strategies. In East Africa, RVF outbreaks are linked with abnormally high rainfall, and can be predicted up to 5 months in advance by modeling approaches using climatic and environmental parameters. However, the application of these models in West Africa remains unsatisfactory due to a lack of data for animal and human cases and differences in the dynamics of the disease emergence and the vector species involved in transmission. Models have been proposed for West Africa but they were restricted to rainfall impact analysis without a spatial dimension. In this study, we developed a mixed Bayesian statistical model to evaluate the effects of climatic and ecological determinants on the spatiotemporal dynamics of the two main vectors. Adult mosquito abundance data were generated from July to December every fortnight in 2005–2006 at 79 sites, including temporary ponds, bare soils, shrubby savannah, wooded savannah, steppes, and villages in the Barkédji area. The results demonstrate the importance of environmental factors and weather conditions for predicting mosquito abundance. The rainfall and minimum temperature were positively correlated with the abundance of Cx. poicilipes, whereas the maximum temperature had negative effects. The rainfall was negatively correlated with the abundance of Ae. vexans. After combining land cover classes, weather conditions, and vector abundance, our model was used to predict the areas and periods with the highest risks of vector pressure. This information could support decision-making to improve RVF surveillance activities and to implement better intervention strategies.

West Nile Virus Infection Rates and Avian Serology in East-Central Illinois

Understanding the geographic role of different species of mosquito vectors and vertebrate hosts in West Nile virus (WNV) transmission cycles can facilitate the development and implementation of targeted surveillance and control measures. This study examined the relationship between WNV-antibody rates in birds and mosquito infection rates and bloodfeeding patterns in east-central Illinois. The earliest detection of WNV-RNA by reverse transcription-polymerase chain reaction TaqMan was from Culex restuans; however, amplification typically coincided with an increase in abundance of Cx. pipiens. Trap type influenced annual estimates of infection rates in Culex species, as well as estimation of blood meal source. Bird species with the highest WNV-antibody rates (i.e., Mourning Doves [Zenaida macroura], Northern Cardinals [Cardinalis cardinalis], American Robins [Turdus migratorius], and House Sparrows [Passer domesticus]) were also the common species found in Culex blood meals. Although antibody rates were not directly proportional to estimated avian abundance, the apparent availability of mammal species did influence proportion of mammal to bird blood meals. Antibody prevalence in the American Robin was lower than expected based on the strong attraction of Culex to American Robins for blood meals. Age-related differences in serology were evident, antibody rates increased in older groups of robins and sparrows, whereas 1st-year hatch and older adults of Mourning Doves and Northern Cardinals had equally high rates of antibody-positive serum samples. The vector and host interactions observed in east-central Illinois (Champaign County), an urban area surrounded by agriculture, are compared to studies in the densely population areas of southern Cook County.

Geographic Distribution and Relative Abundance of the Sibling Vector Species Culex torrentium and Culex pipiens in Sweden

Culex torrentium and Culex pipiens are sibling species and potential viral vectors that coexist in Europe. Larvae and females of the two species are morphologically almost identical, and reliable identification can only be done on males. To investigate the distribution and relative abundance of the two species in Sweden, we collected Culex larvae from sites spread over the country, identified them as Culex pipiens/torrentium based on morphology, and identified them to species using a recently developed restriction enzyme method. Cx. torrentium was the dominant species (89%, n=1012) and it occurred in 48 of the 49 sites investigated, and also dominated in most of the study sites. The proportion of Cx. pipiens larvae in relation to Cx. torrentium collected at each site decreased with both increasing latitude and altitude, and the presence of Cx. pipiens decreased with latitude. In addition, Cx. pipiens/torrentium females were sampled with Centres for Disease Control light traps baited with carbon dioxide. The overall country mean was 4.0 Cx. pipiens/torrentium caught per trap night, with decreasing numbers of Cx. pipiens/torrentium caught per trap night with increasing latitude. Thus, the abundance of Cx. pipiens/torrentium decreased, but the proportion Cx. torrentium increased, with increasing latitude. This is the first study that shows the vast dominance of Cx. torrentium over Cx. pipiens in Sweden. The unexpected dominance of Cx. torrentium highlights the importance of distinguishing between the two species in studies of Culex-borne arboviruses in Europe.

Presença de culicídeos em município de porte médio do Estado de São Paulo e risco de ocorrência de febre do Nilo Ocidental e outras arboviroses

The objectives for this study were to measure the diversity of Culicidae species, describe their abundance and seasonal variation in São José do Rio Preto, SP, and discuss the risk of arbovirus infections. The collection of larval and adult mosquitoes was conducted monthly from 2006 to 2007 in an urban area and four sections of forested land. In the urban area, larvae were collected from sites where oviposition by Culex mosquitoes was most likely to occur. At two of the four sites in the forested land, adult mosquitoes were collected with the use of CDC traps at night, and a Nasci aspirator was used in the daytime at the two other collection sites. In the urban area, 34 Culicidae species were identified out of a total sample of 8,683 specimens; of these specimens, 80.7% were Culex quinquefasciatus, 9.6% were Culex coronator, 3.2% were Aedes albopictus, and 1.1% were Ochlerotatus fluviatilis. The abundance of Cx. quinquefasciatus larvae was negatively related to rainfal. In the woods, 2,268 mosquitoes were collected, representing 10 genera and 46 species. The most abundant mosquito species were Aedeomyia squamipennis, Culex coronator, Culex (Mel.) Melanoconion section, Culex declarator, Ochlerotatus scapularis, Anopheles triannulatus, Culex bidens/interfor and Culex habilitator/pseudojhantinosoma. The abundance of Cx. quinquefasciatus in the urban area and the presence of other Culicidae species in urban areas and forested land point to the possibility of the transmission of West Nile virus and other arbovirus infections in São José do Rio Preto and other cities. Thus, the enacting of measures aimed at the surveillance of these arbovirus infections is essential.

The Effect of Spatial and Temporal Subsetting on Culex tarsalis Abundance Models—a Design for Sensible Reduction of Vector Surveillance

Early identification of increasing mosquito activity is critical to effective mosquito control, particularly when increasing host-seeking behavior may be associated with increased risk of mosquito-borne disease. In this paper, we analyzed the temporal abundance pattern of the West Nile Virus vector, Culex tarsalis, in Fort Collins, CO, using an autoregressive integrated moving average model. We determined that an autoregressive model order 5 with lagged minimum temperatures was best at describing the seasonal abundance of Cx. tarsalis. We then tested the effect of using both temporal and spatial subsets of the data to determine the effect of reduced sampling effort on abundance predictions. We found that, if reduced trapping is necessary due to limited resources, removal of the least productive 1/3 or 1/4 of the traps produced the least erroneous predictions of seasonality represented in the observed data. We show that this productivity-based subset scheme performs better than other sampling effort reductions in generating the best estimate of Cx. tarsalis abundance per trap-night.

The Potential of Cladocerans as Controphic Competitors of the Mosquito Culex pipiens

This study assesses the potential of cladocerans as competitors for controlling the oviposition and larval abundances of mosquitoes. Control of mosquito larvae involving the use of antagonists has focused mostly on predators. We hypothesized that cladoceran competitors have a strong potential to control larval populations of some species of mosquitoes that can be early colonizers of newly-filled waterbodies, and should be less efficient competitors. To test this hypothesis, the establishment and development of larval populations of wild Culex pipiens were investigated in outdoor microcosms varying in terms of Daphnia magna populations. When the population was well established (i.e., high densities of D. magna), oviposition was fully inhibited and there was consequently no mosquito larvae. When the population was more recently established (i.e., lower densities of D. magna), oviposition and larval development of Cx. pipiens occurred. In the absence of D. magna, oviposition, larval biomass, and abundance of Cx. pipiens reached high values. In this situation, conspecifics were inhibiting further oviposition of Cx. pipiens. Based on these results, we suggest that competing zooplankton species, such as D. magna, could be used for the control of mosquito species such as Cx. pipiens. This approach could be beneficial for the management of wetlands.

Temporal Connections between Culex tarsalis Abundance and Transmission of Western Equine Encephalomyelitis Virus in California

Definition of targets for vector control requires an understanding of the relationship between vector abundance and the intensity of arbovirus transmission. Using an extensive surveillance dataset with observations from sentinel chicken flocks and mosquito traps paired in time and space, hierarchical autoregressive logistic regression models were developed to predict the probability of seroconversion in chickens for western equine encephalomyelitis virus (WEEV) based on the relative abundance of the principal vector, Culex tarsalis. After adjustments for confounders, the abundance of Cx. tarsalis 29-42 d before the date of chicken sampling was credibly associated with the risk of WEEV transmission in both the Central and Coachella Valleys, and a doubling of relative Cx. tarsalis abundance was associated with a 58% increase in the odds of seroconversion. The critical time windows identified in our study highlight the need for surveillance of vector populations and forecasting models to guide proactive vector control measures before the detection of transmission to sentinel chickens.

Seasonal Variation in the Abundance of Culex nigripalpus and Culex quinquefasciatus in Wastewater Ponds at Two Florida Dairies

Patterns of seasonal variation in the relative abundance of immature Culex mosquitoes in wastewater ponds at dairies located in 2 different regions of peninsular Florida were compared. Culex nigripalpus and Cx. quinquefasciatus were by far the most common mosquitoes collected during the study (99,344 and 106,225 individuals, respectively). Within-station differences in abundance of Cx. nigripalpus and Cx. quinquefasciatus were evident depending upon time of year. There were also between-station differences in the abundances of the 2 species depending upon time of year and station. Environmental and behavioral factors are implicated in some of the observed differences. We discuss mosquito control options for dairy ponds as well as possible impacts of mosquito production from these areas to humans and to animal health and production.

Spatial distribution and abundance of culicine mosquitoes in realtion to the risk of filariasis transmission in El Sharqiya Governorate, Egypt

Culicine mosquito surveys were conducted in El Sharqiya Governorate (Nov. 2007 - May 2008) in some villages (cities) representing the different districts. Totally 6 species were reported: Culex (Culex) pipiens Linnaeus, Cx. (Cx.) perexiguus Theobald, Cx. (Cx.) antennatus (Becker), Cx. (Barraudius) pusillus Macquart, Cx. (Cx.) sinaiticus Kirkpatrick and Ae. (Ochlerotatus) detritus (Haliday). The last two were identified as newly distributed species. Culex pipiens, the main filariasis vectorwas the predominant or the most common species (ca.88% larvae and 47% adults, p<0.01). For the common species, the following were examined: (1) the type and characteristics (temperature and pH) of the breeding habitats and their relation to the larval density and (2) the relation of adult indoor density and indoor and outdoor temperature and RH. The AMRAD-ICT Filariasis card Test was used to detect the Wuchereria bancrofti antigen in the Finger prick blood samples. Filariasis cases (0.4%, 11/ 2504) were detected in six out of the fifteen districts. The highest infection rate (2.4%) was reported in the 10th of Ramadan, a new settlement area. The cases were associated with the abundance of Cx. pipiens adults (ca. 40- 60% of the collected adults). Digital maps showing the spatial distribution of mosquito species and filariasis cases were generated. Such maps will provide the authorities with more information about the disease risk areas that would assist in the control activities.