Grass Infusions in Autocidal Gravid Ovitraps to Lure Aedes Albopictus.

Aedes albopictus is a vector of several pathogens of significant public health concern. In this situation, gravid traps have become a common surveillance tool for Aedes spp., which commonly use hay infusions as an attractant. Diverse grass infusions have been assessed to enhance the attraction to this vector mosquito. However, these studies have focused on the oviposition effect, and the attraction potential to gravid Ae. albopictus females has not been evaluated yet. Here we report the attractiveness of infusions of 4 different botanical species (Cenchrus purpureus, Cyanodon dactylon, Megathyrus maximus, Pennisetum ciliare) as baits in sticky ovitraps and autocidal gravid ovitraps (AGOs) under laboratory, semifield, and field conditions. In the laboratory, Cynodon dactylon showed attractiveness, whereas in semifield conditions, both C. dactylon and Megathyrsus maximus were similarly attractive for gravid Ae. albopictus. None of the infusions conducted with AGOs were able to lure Ae. albopictus and other species of mosquitoes in a 14-wk field experiment. Our results demonstrate the feasibility of finding more attractive infusions for Ae. albopictus females to improve the efficacy of AGO traps, but further testing of infusions in AGOs in field settings is needed.

Effects of the Weather on the Seasonal Population Trend of Aedes albopictus (Diptera: Culicidae) in Northern Italy.

BACKGROUND: Aedes albopictus, the Asian tiger mosquito, has become a prevalent pest in Italy, causing severe nuisance and posing a threat of transmission of arboviruses introduced by infected travelers. In this study, we investigated the influence of weather parameters on the seasonal population density of Aedes albopictus. METHODS: A Bayesian approach was employed to identify the best meteorological predictors of species trend, using the eggs collected monthly from 2010 to 2022 by the Emilia-Romagna regional monitoring network. RESULTS: The findings show that the winter-spring period (January to May) plays a crucial role in the size of the first generation and seasonal development of the species. CONCLUSIONS: A temperate winter and a dry and cold March, followed by a rainy and hot spring and a rainy July, seem to favor the seasonal development of Ae. albopictus.

Aedes aegypti container preference for oviposition and its possible implications for dengue vector surveillance in Delhi, India.

OBJECTIVES: Dengue is a mosquito-borne viral disease globally transmitted by Aedes aegypti. The most effective method to prevent the transmission of the disease is proficient vector control. Understanding the breeding behaviour of the responsible vectors is very pertinent in this regard; therefore, the present study was conducted to understand Ae. aegypti behaviour regarding the selection of containers for oviposition in the megacity of Delhi. METHODS: A household survey in different localities within Delhi was carried out during 2018-2019. All available containers were inspected for the presence of immature Ae. aegypti. In entomological surveillance, the ovipositional preference of Aedes was computed using the breeding preference ratio, container index in the field, and laboratory settings, and associations of dengue cases with monthly variation in environmental factors and container type were also calculated. RESULTS: The household larval survey in 40 localities showed that 40% of 27,776 water-holding containers in 3,400 houses were plastic, followed by overhead tanks (26.2%), and coolers (12.1%). The most preferred breeding habitat was clay pots (9.3%), followed by metallic containers (8.5%) and solid waste (7.1%). A laboratory-based study showed that Aedes preferred clay containers (81.8%) over 4 other types of containers (plastic, paper, metal, and glass). CONCLUSIONS: The present study provides a rationale for using clay containers as a possible surveillance tool (ovitraps) or as a vector control tool. This information might aid researchers in developing novel traps and targeting preferred containers for larval control activities during transmission and non-transmission seasons.

Invasive Aedes mosquitoes in an urban-peri-urban gradient in northern Spain: evidence of the wide distribution of Aedes japonicus.

BACKGROUND: The expansion of invasive mosquitoes throughout Europe has increased in recent decades. In northern Spain, Aedes albopictus was detected for the first time in 2014, and Aedes japonicus was detected in the three Basque provinces in 2020. This study aimed to evaluate the distribution of these mosquito species and their association with factors related to urbanization. METHODS: In 2021, a total of 568 ovitraps were deployed in 113 sampling sites from 45 municipalities with > 10,000 inhabitants. Oviposition substrate sticks were replaced each fortnight and examined for Aedes eggs from June to November. Aedes eggs were counted, and the eggs from a selection of positive oviposition sticks, encompassing at least one stick from each positive ovitrap, were hatched following their life cycle until the adult stage. When egg hatching was not successful, PCR targeting the COI gene and sequencing of amplicons were carried out. RESULTS: Eggs were detected in 66.4% of the sampling sites and in 32.4% of the ovitraps distributed in the three provinces of the Basque Country. Aedes albopictus and Ae. japonicus were widespread in the studied area, confirming their presence in 23 and 26 municipalities, respectively. Co-occurrence of both species was observed in 11 municipalities. The analysis of the presence of Aedes invasive mosquitoes and the degree of urbanization (urban, suburban, peri-urban) revealed that Ae. albopictus showed a 4.39 times higher probability of being found in suburban areas than in peri-urban areas, whereas Ae. japonicus had a higher probability of being found in peri-urban areas. Moreover, the presence of Ae. albopictus was significantly associated with municipalities with a higher population density (mean = 2983 inh/km2), whereas Ae. japonicus was associated with lower population density (mean = 1590 inh/km2). CONCLUSIONS: The wide distribution of Ae. albopictus and Ae. japonicus observed confirmed the spread and establishment of these species in northern Spain. A new colonization area of Ae. japonicus in Europe was confirmed. Due to the potential impact of Aedes invasive mosquitoes on public health and according to our results, surveillance programs and control plans should be designed considering different urbanization gradients, types of environments, and population density.

Efficacy Assessment of Autodissemination Using Pyriproxyfen-Treated Ovitraps in the Reduction of Dengue Incidence in Parañaque City, Philippines: A Spatial Analysis.

Dengue is one of the most important vector-borne diseases worldwide and is a significant public health problem in the tropics. Mosquito control continues to be the primary approach to reducing the disease burden and spread of dengue virus (DENV). Aside from the traditional larviciding and adulticiding interventions, autodissemination using pyriproxyfen-treated (AD-PPF) ovitraps is one of the promising methods to complement existing vector control strategies. Our paper assessed the efficacy of AD-PPF in reducing DENV infections in two barangays in Parañaque City. Using saliva samples from the participants from both the control and intervention sites, we collected the seroprevalence data for three months in each of the two years. Spatial analysis was conducted to determine hotspot areas and identify DENV infection distributions across the trial periods. The results showed that the intervention site was identified as having a clustering of DENV infections in Month 0 of Year 1 and shifted to a random dispersion of dengue cases at the end of Month 3 in Year 2. The disappearance of the clustering of the intervention site translates to a decrease in the cases of DENV infection relative to the control site. Furthermore, we also identified that DENV transmission occurred at a small-scale level that did not go beyond 86 m. In conclusion, AD-PPF is suggested to be an effective strategy and may be used as an additional vector control approach, albeit based on this short-term implementation.

[Surveillance of the dengue vector at its distribution limit. A collaborative experience between the scientific, municipal and citizen ambits]. / Vigilancia del vector del dengue en el límite de su distribución. Una experiencia colaborativa entre los ámbitos científico, municipal y ciudadano.

INTRODUCTION: In Argentina, during the last decade a southward expansion of the mosquito Aedes aegypti has been observed, accompanied by an expansion in the dengue transmission. The objective of this study was to assess the establishment of the dengue mosquito vector in a locality next to its distribution limits by a collaborative work among scientific, municipal and citizen ambits. METHODS: A vector surveillance system through ovitraps was implemented, and it was complemented by pictures and mosquitoes captured by citizens, and by the active search of breeding sites in different urban spaces of Tandil City, Argentina. RESULTS: The establishment of Aedes aegypti population in the city was demonstrated, both by ovitraps and citizen science contributions. This information made it possible to begin to make the problem visible among municipal authorities and citizens. DISCUSSION: Dengue is an invisible disease in localities in which the mosquito vector has been spreading during the last decade. The information produced by the entomological surveillance is the necessary basis to addresssocial communication to produce behavioral changes in the responsible authorities as well as in the families.

Introducción: En Argentina, durante la última década se ha observado una expansión hacia el sur del mosquito Aedes aegypti, acompañada por la expansión en la transmisión del dengue. El objetivo de este estudio fue evaluar el establecimiento de Ae. aegypti en una localidad cercana al límite de su distribución mediante un trabajo colaborativo entre los ámbitos científico, municipal, y ciudadano. Métodos: Se implementó un sistema de vigilancia del vector mediante ovitrampas, el cual se complementó con fotografías y ejemplares aportados por los ciudadanos, y con búsqueda activa de criaderos del mosquito en distintos espacios urbanos de la ciudad de Tandil, Argentina. Resultados: Se demostró el establecimiento de una población de Ae. aegypti en el municipio, tanto por medio de las ovitrampas como por los aportes del conocimiento y participación de la comunidad: la ciencia ciudadana. La información obtenida permitió comenzar a visibilizar la problemática entre los funcionarios municipales y la ciudadanía. Discusión: El dengue es una enfermedad aún invisible en localidades donde se ha estado expandiendo el mosquito vector durante la última década. La participación pública y la información producida con la vigilancia entomológica es la base necesaria para abordar la comunicación social a fin de producir cambios de conducta en las autoridades responsables y en las familias.

Vigilancia del vector del dengue en el límite de su distribución. Una experiencia colaborativa entre los ámbitos científico, municipal y ciudadano / Surveillance of the dengue vector at its distribution limit. A collaborative ex perience between the scientific, municipal and citizen ambits

Resumen Introducción: En Argentina, durante la última década se ha observado una expansión hacia el sur del mosquito Aedes aegypti, acompañada por la expansión en la transmisión del dengue. El objetivo de este estudio fue evaluar el establecimiento de Ae. aegypti en una localidad cercana al límite de su distribución mediante un trabajo colaborativo entre los ámbitos científico, municipal, y ciudadano. Métodos: Se implementó un sistema de vigilancia del vector mediante ovitrampas, el cual se complementó con fotografías y ejemplares aportados por los ciudadanos, y con búsqueda activa de criaderos del mosquito en distintos espacios urbanos de la ciudad de Tandil, Argentina. Resultados: Se demostró el establecimiento de una población de Ae. aegypti en el municipio, tanto por medio de las ovitrampas como por los aportes del conocimiento y participación de la comunidad: la ciencia ciudadana. La información obtenida permitió comenzar a visibilizar la problemática entre los funcionarios municipales y la ciudadanía. Discusión: El dengue es una enfermedad aún invisible en localidades donde se ha estado expandiendo el mosquito vector durante la última década. La participación pública y la información producida con la vigilancia entomológica es la base necesaria para abordar la comunicación social a fin de producir cambios de conducta en las autoridades responsables y en las familias.

Abstract Introduction: In Argentina, during the last decade a southward expansion of the mosquito Aedes aegypti has been observed, accompanied by an expansion in the dengue transmission. The objective of this study was to assess the establishment of the dengue mosquito vector in a locality next to its distribution limits by a collabora tive work among scientific, municipal and citizen ambits. Methods: A vector surveillance system through ovit raps was implemented, and it was complemented by pictures and mosquitoes captured by citizens, and by the active search of breeding sites in different urban spaces of Tandil City, Argentina. Results: The establishment of Aedes aegypti population in the city was demonstrated, both by ovitraps and citizen science contributions. This information made it possible to begin to make the problem visible among municipal authorities and citizens. Discussion: Dengue is an invisible disease in localities in which the mosquito vector has been spreading during the last decade. The information produced by the entomological surveillance is the necessary basis to address social communication to produce behavioral changes in the responsible authorities as well as in the families.

Effectiveness of autocidal gravid trapping and chemical control in altering abundance and age structure of Aedes albopictus.

BACKGROUND: Aedes albopictus is a nuisance pest mosquito of public health importance commonly managed with adulticides and larvicides. We investigated whether adding Gravid Aedes Traps (GATs), Autocidal Gravid Ovitraps (AGOs) or In2Care traps would extend the effectiveness of chemical control methods in Wake County, North Carolina, USA, by combining barrier sprays and larval habitat management (LHM) with each trap type at suburban households. We compared these three treatment groups to untreated controls and to backyards treated only with barrier sprays and LHM. Once a week, for ten weeks, we collected adult mosquitoes at each house using lure-baited surveillance traps and dissected a portion of Ae. albopictus females to determine parity. RESULTS: Barrier sprays and LHM alone or combined with any supplemental autocidal ovitrap significantly reduced female Ae. albopictus through Week 3 post-treatment. GATs significantly extended chemical control effectiveness for the duration of the study. Compared to the untreated control, the AGO and GAT treatment groups had significant overall female Ae. albopictus reductions of 74% and 80.4%, respectively, with populations aging significantly slower at houses treated with AGOs. CONCLUSION: This household-level study, though limited in size, observed significant reductions in nuisance Ae. albopictus when combining AGOs and GATs with chemical controls for an eight-week period. Delayed population aging in AGO-treated yards suggests that traps also could mitigate disease transmission risk. Future studies should test these control methods at the neighborhood level to evaluate large-scale effectiveness as well as assess the effect of autocidal ovitraps without chemical intervention. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

First Nationwide Monitoring Program for the Detection of Potentially Invasive Mosquito Species in Austria.

In Austria, only fragmented information on the occurrence of alien and potentially invasive mosquito species exists. The aim of this study is a nationwide overview on the situation of those mosquitoes in Austria. Using a nationwide uniform protocol for the first time, mosquito eggs were sampled with ovitraps at 45 locations in Austria at weekly intervals from May to October 2020. The sampled eggs were counted and the species were identified by genetic analysis. The Asian tiger mosquito Aedes albopictus was found at two sites, once in Tyrol, where this species has been reported before, and for the first time in the province of Lower Austria, at a motorway rest stop. The Asian bush mosquito Aedes japonicus was widespread in Austria. It was found in all provinces and was the most abundant species in the ovitraps by far. Aedes japonicus was more abundant in the South than in the North and more eggs were found in habitats with artificial surfaces than in (semi-) natural areas. Further, the number of Ae. japonicus eggs increased with higher ambient temperature and decreased with higher wind speed. The results of this study will contribute to a better estimation of the risk of mosquito-borne disease in Austria and will be a useful baseline for a future documentation of changes in the distribution of those species.

Asian Tiger Mosquito in Yucatan Peninsula: First Record of Aedes (Stegomyia) albopictus (Diptera: Culicidae) in Campeche, Mexico.

This report describes the presence of Aedes albopictus Skuse (Diptera: Culicidae) in Yucatan Peninsula and represents the first record of the Asian tiger invasive mosquito in Campeche State, southeastern Mexico. We collected specimens using 11,326 ovitraps put into houses of urban and rural areas, as part of the entomological surveillance by the local Ministry of Health from January 2019 to February 2020. We found Ae. albopictus in five of the 12 municipalities of Campeche (San Francisco de Campeche, Tenabo, Hecelchakán, Calkíni and Escárcega). We record 68 positive ovitraps and 226 Ae. albopictus larvae. This finding increases the number of mosquito species recorded in Campeche, Mexico, and possibly the potential for 22 arbovirus transmission.

Progressive Invasion of Aedes albopictus in Northern Spain in The Period 2013-2018 and A Possible Association with the Increase in Insect Bites.

1) Background: Aedes albopictus has rapidly expanded throughout Europe, becoming a public health concern in the Mediterranean Basin. 2) Methods: Following the detection of Ae. albopictus in the southwestern French region of Aquitaine in 2012, an entomological surveillance programme was implemented in the Basque Country (Northern Spain) in 2013. 3) Results: Ae. albopictus eggs were first detected in 2014 in a transited parking area in the northeastern sampling point, 22 km away from the nearest French site with recorded presence of tiger mosquito. At this site, eggs were found throughout the study (2014-2018). Other western and southern municipalities became positive in 2017 and 2018. Ae. albopictus adults were first captured in 2018 by aspiration of the vegetation in an area where eggs had been detected since 2015, suggesting a progressive establishment of a self-sustained population. Incidence of insect bites in humans was roughly constant over the study period except for a significant increase in 2018 in the Health County where eggs had been detected since 2014. Densities of Ae. albopictus eggs in positive areas remained at similar levels over the years. 4) Conclusion: Multiple approaches and standardized methods are necessary to successfully control this vector.

Aedes aegypti Invades Trindade Island, 1,140 km from the Brazilian Coast, in the South Atlantic.

Herein we report the first recorded arrival of Aedes aegypti on Trindade Island, approximately 1,140 km from the Brazilian coast, posing potential health risks to the human inhabitants thereof. The collection of mosquitoes was done from August to October 2019 via an active search for adults, eggs, and larvae by surveying objects with accumulated water and implantation of 23 ovitraps in different regions of the island. As a result, we collected 33 adults of Ae. aegypti via active search inside buildings. A total of 433 eggs of Ae. aegypti were also obtained from the ovitraps, all of which subsequently reached the adult stage. No other species of Culicidae was found.

Infestation of an endemic arbovirus area by sympatric populations of Aedes aegypti and Aedes albopictus in Brazil

BACKGROUND Aedes aegypti and Aedes albopictus are the most important arbovirus vectors in the world. OBJECTIVES This study aimed to investigate and compare the infestation pattern of these species in a neighbourhood of Recife, Brazil, endemic for arboviruses in 2005 (T1) and 2013 (T2). METHODS Infestation, distribution and relative abundance of these sympatric species were recorded by egg collection using a network of 59 sentinel ovitraps (s-ovt) at fixed sampling stations for 12 months in T1 and T2. FINDINGS A permanent occupation pattern was detected which was characterised by the presence of egg-laying females of one or both species with a high ovitrap positivity index (94.3 to 100%) throughout both years analysed. In terms of abundance, the total of eggs collected was lower (p < 0.005) in T2 (146,153) than in T1 (281,103), although ovitraps still displayed a high index of positivity. The spatial distribution showed the presence of both species in 65.1% of the 148 s-ovt assessed, while a smaller number of traps exclusively contained Ae. aegypti (22%) or Ae. albopictus (13.2%) eggs. MAIN CONCLUSIONS Our comparative analysis demonstrated the robustness of the spatial occupation and permanence of Ae. aegypti and Ae. albopictus populations in this endemic urban area.

Monitoring of alien mosquitoes of the genus Aedes (Diptera: Culicidae) in Austria.

Systematic, continuous mosquito surveillance is considered the most reliable tool to predict the spread and establishment of alien mosquito species such as the Asian tiger mosquito (Aedes albopictus), Japanese bush mosquito (Aedes japonicus), and the transmission risk of mosquito-borne arboviruses to humans. Only single individuals of Ae. albopictus have been found in Austria so far. However, it is likely that the species will be able to establish populations in the future due to global trade and traffic as well as increasing temperatures in the course of global climate change. In summer 2017, a project surveilling the oviposition of newly introduced Aedes mosquitoes, using ovitraps, was set up by means of citizen scientists and researchers and was performed in six federal provinces of Austria-Tyrol, Carinthia, Vienna, Lower Austria, Styria, and Burgenland. Eggs of Ae. albopictus were identified in Tyrol during the months August and September, while Ae. japonicus was found in Lower Austria, Styria, and Burgenland. In Vienna and Carinthia, all ovitraps were negative for Aedes eggs; however, Ae. japonicus was found for the first time in Vienna in July 2017 during routine sampling of adult mosquitoes. With this project, we demonstrated the benefits of citizen scientists for ovitrap-based mosquito surveillance. The finding of Ae. albopictus eggs in Northern Tyrol is not yet a proof of the establishment of a self-sustaining population, although it indicates the ongoing introduction of this species along main traffic routes from Italy, where this mosquito is well established. The risk of establishment of the tiger mosquito in the Lower Inn Valley is therefore a given and informing the public about preventive measures to hinder and delay this development is highly recommended.

Evaluation of enhanced oviposition attractant formulations against Aedes and Culex vector mosquitoes in urban and semi-urban areas.

Surveillance is not only an important tool to assess the population dynamics of vector mosquitoes, but it can also be used to control vector-borne diseases. Mosquito vectors that belong to several genera such as Anopheles, Aedes, and Culex play a crucial role in the transmission of malaria, dengue, chikungunya, Zika, and elephantiasis diseases worldwide. We tested the efficacy of two commercial-grade oviposition attractant formulations that were developed for the container-inhabiting Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus mosquitoes present in urban or semi-urban environments. These attractants can lure gravid females. Field trials were conducted in residential yards during a post-rainy season in September and October. Our data showed considerable efficacy for both attractants. Aedes-attractant collected 1.6-fold more larvae (101.2 ± 10.5 larvae/trap) than the control, and Culex-attractant collected 1.27-fold more larvae (151.2 ± 12.5 larvae/trap) than the control, resulting in 0.8 and 0.7 oviposition attraction indices (OAIs), respectively. Regression analysis indicated that the Aedes-attractant was more stable than the Culex-attractant. Location and time did not alter the efficacy of these attractants. Our experiment suggests that these attractants can be used for the development of species-specific gravid traps to detect, estimate, and control the mosquito population in urban and semi-urban areas.

Relationship between local presence and density of Aedes aegypti eggs with dengue cases: a spatial analysis approach.

OBJECTIVES: To analyze the relationship between the occurrence of dengue and ovitrap positivity and dengue egg density in two Amazonas municipalities (Brazil) in 2016. METHODS: We performed a case-control study using secondary data from the dengue fever surveillance system. Ovitraps distributed regularly in the urban area of two cities were used to monitor the presence of the vector. The relationship between egg positivity, egg density and the location of dengue cases was evaluated using two approaches as follows: (i) based on the result of the nearest neighbour ovitrap and (ii) based on the results of the set of ovitraps within the influence area of 300 m from the location of each case and control. RESULTS: During the study period, 229 confirmed cases of dengue fever were reported in Tabatinga and 89 cases in Itacoatiara. In this study, we found that the positivity of ovitraps was related to the occurrence of dengue in Tabatinga and Itacoatiara. An association between egg density of Ae. aegypti and dengue occurrence was also observed in Itacoatiara. The temporal lags for ovitrap positivity measurements were predominantly 15 or 30 days. A dengue association for egg density for a 15-day time lag was detected for one of the case-control approaches. CONCLUSIONS: The location of dengue cases is related to ovitrap egg positivity, while a less evident possible association may exist for egg density. This indicates that these traps could be used to improve vector control actions.

Oviposition preferences of dengue vectors; Aedes aegypti and Aedes albopictus in Sri Lanka under laboratory settings.

Investigations on oviposition behaviour of dengue vectors are critical for effective controlling of vector breeding. Therefore, the aim of the present study was to determine the oviposition behaviour of dengue vectors, Aedes aegypti and Aedes albopictus in Sri Lanka. Batches of 1000 adult mosquitoes (1 : 1, male: female ratio) housed in rearing cages were used for each experimental setup from Ae. aegypti and Ae. albopictus. Oviposition responses with respect to the size of the ovitrap, colours of the ovitrap, water source, sodium chloride (NaCl) concentration and presence/absence of larvae were evaluated by enumerating the number of eggs laid in the ovitraps. The analysis of variance and cluster analysis were used to investigate the significance in the variations among oviposition. The number of eggs laid by both species were improved with the increasing size of ovitraps. Ae. albopictus indicated the highest mean number of eggs in 0.2% of NaCl than in the ovitraps filled with distilled water. However, the egg laying preference was reduced with increasing salinity in both species. Drain water with low dissolved oxygen (DO) level (0.43 ± 0.12 mg l-1) was the preferred water source for both species, while a significantly high oviposition rate was observed in ovitraps with larvae. Black colour ovitraps attracted the majority of gravid females, while white was least preferred. There were no significant variations among oviposition behaviours of Ae. albopictus and Ae. aegypti. The ability of these vectors to breed in waste water with low DO levels may lead them to attain wide dissemination in the natural environment, enhancing their potential threat to human life.

A survey of mosquito species in public schools of Metro Manila, Philippines using Ovitraps as surveillance tool

@#<p style="text-align: justify;"><strong>OBJECTIVE:</strong> This study assessed the species composition of mosquitoes collected from ovitraps in selected public schools of Metro Manila, Philippines.</p><p style="text-align: justify;"><strong>MATERIALS AND METHODS:</strong> Ovitraps were installed from November 2013 to February 2014, in purposively selected public elementary and high schools of Metro Manila. Ovitraps were installed inside classrooms and collected weekly and examined for mosquito eggs and larvae. Speciation was done once a month from November 2013 to February 2014. All positive paddles were immersed in water for larval emergence, reared to fourth instars and were identified using taxonomic keys.</p><p style="text-align: justify;"><strong>RESULTS:</strong> A total of 1,482 ovitraps were installed in the selected public schools, and 18,325 larvae were collected from elementary schools, while 16,670 larvae were collected from high schools. The mean ovitrap index or infestation rate was 49.69% during the period of data collection. Mosquito larvae were identified as Aedes aegypti (88.94%) and Aedes albopictus (11.06%). Aedes aegypti and Aedes albopictus coexisted in some of the examined paddles. No significant differences were observed between the type of school and the presence of Aedes larvae. Significant differences were observed between total number of mosquito larvae and months of collection.</p><p style="text-align: justify;"><strong>CONCLUSION:</strong> The presence of Aedes mosquitoes in schools evidently shows that continuous vector surveillance in schools is necessary as this information will help in the formulation of proactive vector control activities, thereby preventing the occurrence of mosquito-borne diseases.</p>

Transovarial transmission of DENV in Aedes aegypti in the Amazon basin: a local model of xenomonitoring.

BACKGROUND: Transovarial transmission of dengue virus in Aedes spp. mosquitoes is considered an important mechanism for the maintenance of the virus in nature and may be implicated in the occurrence of outbreaks and epidemics of the disease. However, there are few studies involving transovarial transmission and viral vector monitoring as a surveillance tool and control strategy. The present study evaluated transovarial transmission of dengue virus in Aedes aegypti populations as a xenomonitoring strategy in municipalities of the Amazonas state. RESULTS: Aedes sp. eggs (13.164) were collected, with 30% viability of third- and fourth-instar larvae. Transovarial transmission of DENV was detected in all municipalities. The transovarial infection rate (TOR) in the municipalities was 46% of the DENV positive samples. The minimum infection rate (MIR) was 17.7 in the state, varying from 11.4 to 24.1 per 1,000 larvae tested in the respective municipalities. Four DENV serotypes were identified, with DENV I and IV being present in all municipalities investigated. The number of reported dengue fever cases varied during this period. CONCLUSIONS: Our results suggest that transovarial transmission may be an important mechanism for the maintenance and spreading of the disease in Amazonas municipalities. Using qRT-PCR, it was possible to identify the four DENV serotypes in larval samples. The methodology used in the present study proved suitable as a DENV xenomonitoring model in immature mosquitoes, contributing to the development of systems for early detection of viral circulation and predictive models for the occurrence of outbreaks and epidemics of this disease. TRIAL REGISTRATION: CAAE34025414200005015 .

Oviposition substrate in Asian tiger mosquito surveillance: Do the sizes matter?

Ovitraps are regarded as a reliable system to monitor Aedes albopictus dynamics. However, the dimensions of the oviposition substrate are not standardized, and no studies have investigated which should be the most effective sizes. In this study, the effect of paddle sizes in tiger mosquito egg collection was evaluated. Egg count and density on the wide surfaces and margins of different-sized oviposition substrates have been evaluated in two studies (A and B). In study A, a total of 29,995 Ae. albopictus eggs was counted in 250 classic oviposition substrates. Eggs were found on both wide surfaces (53.1%) and margins (46.9%). Egg density was significantly larger in margins compared to wide surfaces. Overall in study B, 983 Ae. albopictus eggs were collected. According to paddle sizes, 51.8% of eggs were on large and 48.2% on small paddles. Mean egg density of wide surfaces was significantly larger in small paddles (0.25 eggs/cm(2) ) compared to large paddles (0.06 eggs/cm(2) ). Results indicate that wider oviposition substrates do not mean larger number of Ae. albopictus eggs. Indeed, on paddles four times thinner than others, the number of eggs counted was not statistically different. These findings suggest that small paddles may be routinely employed in ovitraps, thus allowing savings of materials and money.