Evaluation of a new type of mosquito trap in monitoring Aedes in community / 上海预防医学

ObjectiveTo develop a new mosquito trap and evaluate its effectiveness in Aedes albopictus monitoring in an urban community. MethodsThe first-round field test was conducted in a well-greened residential neighborhood with high Aedes albopictus density calculated by human landing catch in August 2022， in Minhang District， Shanghai. 65 new test containers with different designs were randomly deployed in the field. These trap containers were designed by different material， color， hole size， shape and top cover colors. The results of mosquito and its egg trapping were observed and recorded continuously for 7 days. In September 2022， the second round of experiment was conducted. After comparison， an optimized trap container was designed. 140 new trap containers were compared with 140 traditional ones to evaluate the effectiveness. SPSS 22.5 software was used for statistical analysis. ResultsThere were significant changes in the outcome of mosquito and its egg trapping on the 4th and 7th day of the pre-experiment deployment of the three kinds of containers. The 200 ml container cup with three round holes in the body had the best effect on trapping mosquitos and eggs， with a positive rate of 45.5% （5/11）， while other type of contrainer cup only had a positive rate of 12% （6/50） in trapping mosquitos and eggs. Statistical significant differences （χ2=45.443，P <0.001） existed between the two tpyes of cups within the first kind of trapping container. The second kind of trapping container showed round and oval holes had better effect on mosquito trapping， with a positive rate of 55.6% （5/9）. The third kind of hanging container can resist strong wind. The best mosquito trapping effect of three round holes was 66.7% （2/3）. The container wall should not be made of rough material， which was easy to cause the escape of adult mosquitoes. Combined with the three types of containers， the new contariner should be top transparent， and the top 1/3 of the side should paint black with 3 round holes. The effective recovery rate of the new container was higher than that of the traditional one under the exclusion of human factors， and had the advantage of preventing rain， wind and rollover， but the effect of trapping mosquito and its egg was comparable to the traditional one（χ2D4=0.197，P=0.658； χ2D7=0.125 ，P=0.724）. ConclusionThis new type of mosquito trap is worth further exploration and research， which can improve the trapping efficiency， overall recovery rate and the accurate confirmation of the mosquito density.

Distribution and density of Aedes albopictus in Jiading District of Shanghai in 2020 / 上海预防医学

Objective To determine the seasonal fluctuation and population distribution of Aedes albopictus in Jiading District， and provide scientific evidence for the prevention and control of dengue fever and other Aedes-borne diseases. Methods In 2020， the mosq-ovitrap method and mosq-ovitrap index （MOI） were used to monitor and evaluate the density of Aedes albopictus in Jiading District. Spatial and temporal distribution of Aedes albopictus was determined. Chi-square test was used for statistical analysis. Results In 2020， the annual average MOI was determined to be 4.10， which was under safety threshold. The seasonal fluctuations showed a unimodal distribution， which peaked in July. The fluctuation trend in urban area was similar to the overall trend， while that in the non-urban area showed a bimodal distribution with peaks in June and August. The density of Aedes albopictus at different monitoring sites varied widely，with the highest MOI （6.64） at Anting town and the lowest MOI （2.09） at Huating town. The distribution of Aedes albopictus in different habitats also varied widely； the highest density was observed in environments as waste collection stations and construction sites， with the highest MOI 33.33 in waste collection stations in peak season. The MOI value of Aedes albopictus in residential areas was significantly higher than that in non-residential areas （χ2 = 6.082， P = 0.014）. Conclusion Aedes albopictus is quite common in Jiading District. In certain areas， Aedes density may exceed the safety threshold from May to September. More targeted mosquito control measures should be implemented in waste collection stations， construction sites and residential areas.

Spatial and temporal distribution of Aedes albopictus monitored by mosq-ovitrap in Songjiang District of Shanghai in 2018—2020 / 上海预防医学

Objective Based on mosq-ovitrap monitoring method of Aedes albopictus， to determine the spatial and temporal distribution of Aedes albopictus in Songjiang District and provide scientific evidence for prevention and control of mosquito-borne diseases. Methods From May to October， 2018‒2020， density of Aedes albopictus was monitored by using the mosq-ovitrap method. Sub-districts and towns were used as the monitoring units and the difference in mosquito ovitrap index （MOI） was compared by seasons， years and habitats. Results The total number of positive mosquito ovitraps was 1049 in 2018‒2020， and the average MOI was 8.10. Four sub-districts/towns in the urban area and the northern area had the relatively high MOIs. Moreover， MOIs in residential and external environments were higher than other habitats. In addition， MOI of Aedes albopictus decreased over years from 2018 to 2020. Conclusion Aedes albopictus is widely distributed in Songjiang District. Although the number of mosquito decreased over years after the implementation of mosquito control measures， reproduction of mosquito remains excessive in some areas and seasons. It is necessary to perform targeted control measures based on comprehensive monitoring methods.

PesTrapp mobile app: A trap setting application for real-time entomological field and laboratory study

@#Diseases such as malaria, dengue, Zika and chikungunya remain endemic in many countries. Setting and deploying traps to capture the host/vector species are fundamental to understand their density and distributions. Human effort to manage the trap data accurately and timely is an exhaustive endeavour when the study area expands and period prolongs. One stop mobile app to manage and monitor the process of targeted species trapping, from field to laboratory level is still scarce. Toward this end, we developed a new mobile app named “PesTrapp” to acquire the vector density index based on the mobile updates of ovitraps and species information in field and laboratory. This study aimed to highlight the mobile app’s development and design, elucidate the practical user experiences of using the app and evaluate the preliminary user assessment of the mobile app. The mobile app was developed using mobile framework and database. User evaluation of the mobile app was based on the adjusted Mobile App Rating Scale and Standardized User Experience Percentile Rank Questionnaire. The process flows of system design and detailed screen layouts were described. The user experiences with and without the app in a project to study Aedes surveillance in six study sites in Selangor, Malaysia were elucidated. The overall mean user evaluation score of the mobile app was 4.0 out of 5 (SD=0.6), reflects its acceptability of the users. The PesTrapp, a one-stop solution, is anticipated to improve the entomological surveillance work processes. This new mobile app can contribute as a tool in the vector control countermeasure strategies.

Efecto de la combinación de Metarhizium anisopliae y Gliocladium virens sobre la oviposición, eclosión y emergencia de Aedes aegypti / Effect of the combination of Metarhizium anisopliae and Gliocladium virens on the oviposition, hatching and emergency of Aedes aegypti

Resumen: Objetivo: Evaluar el efecto de la combinación de Metarhizium anisopliae y Gliocladium virens, ambos con Aqua Reslin Super, sobre oviposición, eclosión y emergencia de Aedes aegypti. Material y métodos: Se realizaron evaluaciones para determinar el efecto de los tratamientos impregnados en papel filtro y expuestos dentro de recipientes de plástico sobre la oviposición, eclosión y emergencia de Aedes aegypti. Resultados: Los resultados indicaron que las combinaciones hongo e insecticida no afectaron el comportamiento de oviposición, pero sí la eclosión de los huevos y la emergencia del adulto. Conclusión: Con los resultados se puede concluir que la combinación de hongos + insecticida puede ser una buena opción para aplicarse en sitios de oviposición con miras al desarrollo de una ovitrampa letal.

Abstract: Objective: To evaluate the effect of the combination of Metarhizium anisopliae and Gliocladium virens, both with Aqua Reslin Super, on the oviposition, hatching and emergence of Aedes aegypti. Materials and methods: Evaluations were carried out to determine the effect of treatments impregnated on filter paper and exposed within plastic containers on the oviposition, hatching and emergency of Aedes aegypti. Results: The results indicated that the fungus and insecticide combinations did not affect the oviposition behavior, but if the hatching of the eggs and the adult's emergency. Conclusion: With the results it can be concluded that the combination of fungi + insecticide can be a good option to be applied in oviposition sites with a view to the development of a lethal ovitrap.

Avaliação da armadilha ovitrampa iscada com atraente natural para o monitoramento de Aedes spp. em Dili, capital do Timor-Leste / Evaluation of the baited ovitrap with natural attractant for monitoring Aedes spp. in Dili, capital of East Timor

Resumo A dengue ocorre no Timor-Leste desde 2005, porém não existe um programa de monitoramento e controle do "Aedes aegypti". O objetivo deste estudo foi de avaliar a armadilha ovitrampa iscada com atraente natural como uma possível ferramenta para monitorar o vetor das arboviroses: Dengue (DENV), Chikungunya (CHIKV) e Zika (ZIKV). O estudo foi realizado na cidade de Dili, capital do Timor-Leste, entre as semanas epidemiológicas 32 (02/08) a 48 (02/12) de 2016. Foram instaladas 70 armadilhas Ovitrampa, em residências de 15 sucos (ruas), de quatro Postos Administrativos (bairros) da cidade. Para as analises dos dados utilizou-se os indicadores entomológicos: Índice de Positividade de Ovitrampa (IPO), Índice de Densidade Vetorial (IDV) e Índice de Densidade de Ovos (IDO). Durante o experimento foram coletados 158.904 ovos de Aedes spp.. O IPO demonstrou que todas as áreas tiveram 98% a 100% de armadilhas contendo ovos de Aedes spp.. Os indicadores IDO e IPO apresentaram correlações positivas e significativa com a temperatura. A defasagem de duas e três semanas para precipitação indicou correlação positiva significativa para IDV e IDO. Portanto, a armadilha ovitrampa é uma ferramenta que pode integrar as ações de um programa de monitoramento e controle de Aedes spp. no Timor-Leste.

Study on the Distribution and Abundance of Aedes aegypti and Aedes albopictus in Different Environment Settings for HighRise Buildings

Abstract@#Introduction: Vector surveillance in high-rise buildings is important to predict and monitor the presence of vectors regarding their abundance and distribution. In this study, the infestation profile of Aedes aegypti and Aedes albopictus species in different environmental settings were investigated. Methods: Four high-rise apartments in four different localities were selected for ovitrap surveillance. Fifty ovitraps were placed in semi indoor and outdoor settings. Results: A total of 507 (42.8%) from ovitraps showed the presence of the Aedes species larvae. Out of these, 170 (33.5%) of the positive ovitraps were those placed in semi indoor and 337 (66.5%) in outdoor. Of the total 16,613 Aedes larvae found, 4,130 (24.9%) were from semi indoor, and 12,483 (75.1%) from outdoor. In terms of distribution, Ae. albopictus was predominantly found in outdoor environments (POI=87.5%; MLT=36.45 larvae). Ae. aegypti was also found in outdoor environments (POI=14.89%; MLT=8.26 larvae). There was a significant difference in POI for both Ae. aegypti and Ae. albopictus in the two different environments but no significant difference was observed in MLT, indicating that the density of the Aedes species in both environments was well distributed. Conclusion: In this study, the patterns of Aedes habitat in high-rise apartments were observed. This study has shown an invasion and adaptation of Aedes mosquitoes into the ecosystems of high-rise buildings. It can be concluded that housing designs and the condition of the surrounding environment affects the infestation profile and the distribution of Aedes mosquitoes.

Spatial distribution of Aedes aegypti (Diptera: Culicidae) in vulnerable areas for the transmission of arboviruses

Abstract INTRODUCTION: Areas at risk of transmission of arboviruses have been monitored using ovitraps. This study aimed to evaluate the spatial distribution of Aedes aegypti in vulnerable areas for the transmission of arboviruses and assess the influence of climatic conditions on the infestation of these culicids. METHODS: Ovitraps were installed in Agrestina, Pernambuco, Northeastern Brazil. RESULTS: Overall, 44,936 eggs were collected, and the indexes of infestation varied. Relative humidity was significantly associated with the infestations. CONCLUSIONS: Using ovitraps, entomologic indexes and analysis of climatic factors might be good strategies for monitoring vulnerable areas for the transmission of arboviruses.

Definition of dengue risk thresholds of route index and mosq-ovitrap index / 预防医学

Objective @#To estimate the risk threshold of route index（RI）and mosq-ovitrap index（MOI）based on Breteau index（BI）,as supplements for dengue fever risk monitoring in specific habitats. @*Methods @#Two towns and two streets were selected from nine towns（streets）in Jiashan County,and then one village（community）was selected from each of them as a Aedes albopictus monitoring site. The BI,RI and MOI were employed at the same time and area from April to October in the year 2018. Linear regression models were built with RI,MOI and BI to calculate the dengue risk threshold of RI and MOI according to BI. @*Results @#The linear regression model of BI（X）and RI（Y）was Y=0.145+0.662X（P<0.05）,of BI（X）and MOI（Y）was Y=3.423+0.524X（P<0.05）. If BI=5（having risk of transmission of dengue fever）,then RI=3.455（95%CI：1.717-5.198）,MOI=6.043（95%CI：-0.327-12.417）. If BI=10（having risk of outbreak）,then RI=6.765（95%CI：5.018-8.518）,MOI=8.663（95%CI：2.260-15.071）. If BI=20（having risk of epidemic）,then RI=13.385（95%CI：11.326-15.453）,MOI=13.903（95%CI：6.352-21.461）.@*Conclusion @#The dengue fever risk threshold of RI estimated by BI had a narrow 95%CI and could be applied for dengue fever risk assessment,while the risk threshold of MOI had a wide 95%CI and the application value needed further study.

Association of dengue fever with Aedes spp. abundance and climatological effects / Asociación de casos de dengue con variación en la abundancia de Aedes y clima

Abstract: Objective: To analyze the association of dengue fever incidence with Aedes mosquito's abundance, and the effect of climatological and geographical variables, in a region in Morelos State, Mexico. Materials and methods: Weekly data during the period 2010 to 2014 was used. Mosquito abundance was determined using ovitraps. Confirmed dengue cases were obtained from the Epidemiological Surveillance System. Climatic variables were obtained from weather monitoring stations. The correlation between climate variables and ovitraps data was estimated using a multivariate regression model. Results: A correlation of mosquito abundance with dengue fever incidence, and a yearly pattern with seasonal variations were observed. The daily mean temperature, relative humidity and rainfall parameters were associated with mosquito egg abundance. Time lags of three and four weeks between egg counts and dengue fever incidence were observed. Conclusion: Time lags between egg counts and dengue incidence could be useful for prevention and control interventions.

Resumen: Objetivo: Analizar la asociación de la incidencia de dengue con la abundancia de mosquitos Aedes y el efecto de variables climatológicas, en una región de Morelos, México. Material y métodos: Se utilizaron datos semanales durante el 2010-2014. La abundancia de mosquitos se determinó utilizando ovitraps. Los casos de dengue se obtuvieron del Sistema de Vigilancia Epidemiológica. Las variables climáticas se obtuvieron de estaciones climatológicas locales. La correlación entre las variables climáticas y los datos de ovitrampas se estimó mediante un modelo de regresión multivariado. Resultados: Se observó una correlación de la abundancia de mosquitos con la incidencia de dengue. La temperatura media diaria, humedad relativa y la precipitación pluvial se asociaron con abundancia de mosquitos. Se observó un desfase temporal de tres a cuatro semanas entre cuentas de huevos y la incidencia de dengue. Conclusión: Los intervalos entre las cuentas de huevos y la incidencia de dengue podrían ser utilizados para planear intervenciones de prevención y control.

Updated distribution of Aedes albopictus (Diptera: Culicidae) in Spain: new findings in the mainland Spanish Levante, 2013

In 2004, Aedes (Stegomyia) albopictus (Skuse, 1894) was observed for the first time in Catalonia, northeastern Spain. A decade later, it has spread throughout the eastern Mediterranean region of the country and the Balearic Islands. Framed within a national surveillance project, we present the results of monitoring in 2013 in the autonomous communities of the mainland Levante. The current study reveals a remarkable increase in the spread of the invasive mosquito in relation to results from 2012; the species was present and well-established in 48 municipalities, most of which were along the Mediterranean coastline from the Valencian Community to the Region of Murcia.

Spatiotemporal distribution of dengue vectors & identification of high risk zones in district Sonitpur, Assam, India.

Background & objectives: Dengue is an arboviral disease of public health importance in many parts of India and recently many cases have been reported from northeastern India. Aedes mosquitoes, which are the vectors of dengue, are widely prevalent in the region. A study was initiated in Sonitpur district of Assam to understand the spatiotemporal distribution and seasonal prevalence of dengue vectors and to identify the high risk zones. Methods: Ovitrap surveys were conducted in three randomly selected villages under each of the eight public health centres (PHC) in district Sonitpur of Assam, northeastern India during March 2011 - February 2012. Three risk zones (high, medium and low) were identified on the basis of per trap density of Aedes mosquitoes. Meteorological data were collected to study the temporal distribution of dengue vectors. Results: Aedes albopictus (99.3%) was the predominant dengue vector followed by Ae. aegypti (0.7%) recorded in the ovitraps. The highest vector density was observed during the post-monsoon (60.1 ± 18 per trap) while the lowest during the winter (7.6 ± 4.9 per trap) and the season-wise differences in the vector density were significant (p=0.005). Maximum temperature (correlation coefficient, r = 0.45) and minimum temperature (r = 0.408) showed the highest positive correlation with the vector density, whereas the number of rainy days showed high positive correlation (r = 0.185) than the total rainfall (r = 0.117). The high risk zone (Dekhiajuli, Behali, Bihaguri and Gohpur PHC) as indicated by the high larval densities of dengue vectors, 45.3 ± 18, 42.1 ± 22.3, 36.9 ± 29.1, 35.3 ± 22.6 per trap, respectively, was validated by dengue epidemiological data collected during 2012. Interpretation & conclusions: Yearlong monitoring of dengue vectors was done for the first time in this region. Monthly maximum temperature and the number of rainy days could be used for the prediction of larval density of Aedes mosquitoes. The identification high dengue risk zones would help in adopting targeted interventions for disease management in future.

Laboratory and field evaluation of the effects of the neonicotinoid imidacloprid on the oviposition response of Aedes (Stegomyia) aegypti Linnaeus (Diptera: Culicidae)

In this paper, we assessed the suitability of using the neonicotinoid imidacloprid with standard ovitraps by evaluating the ovicidal properties of imidacloprid and its influence on the oviposition response of gravid females of Aedes (Stegomyia) aegypti Linnaeus (Diptera: Culicidae). First, we calculated the imidacloprid lethal dose 99 (LD99) by exposing third instar larvae of the target species to different concentrations of the insecticide. Next, Ae. aegypti eggs were exposed to the imidacloprid LD99 for 24 h and hatching inhibition was recorded. Finally, we investigated any potential repellent effect of the imidacloprid solution on the oviposition response of gravid Aedes females in field and laboratory conditions. The LD99 obtained from larvae tests proved to be sufficient to keep any exposed eggs from hatching. No repellent effect was observed; females laid as many eggs in imidacloprid-treated ovitraps as in traps containing either clean water or temephos-treated water in both field and laboratory conditions. Our results indicate that imidacloprid is a suitable insecticide for treating ovitraps against Ae. aegypti.

Monitoring temporal fluctuations of Culex quinquefasciatus using oviposition traps containing attractant and larvicide in an urban environment in Recife, Brazil

The use of attractants and larvicides in oviposition traps is of practical interest for the surveillance and control of urban mosquitoes. In addition to increasing the safety of the traps, this combination is essential for an attract-and-kill control strategy based on trapping mosquito eggs. The combination of Bacillus thuringiensis var. israelensis (Bti) and grass infusion (GI) vs. GI alone were tested for their ability to attract in paired BR-OVT traps in the backyards of 10 houses in Recife, Brazil, for a period of 45 days. Results show that females prefer to oviposit in traps containing Bti (363 compared with 251 egg rafts over 45 days). Results from a one-year trial on the efficacy of BR-OVT traps loaded with GI and Bti as a sampling tool to monitor temporal fluctuations in the population densities of Culex quinquefasciatus in an urban environment are also reported. From December 2006-January 2007, one trap per home was installed and maintained for 348 consecutive days in 134-151 houses located in three urban blocks. Throughout the one-year field trial a total of 43,151 Culex egg rafts were collected in the traps. The data show that BR-OVT loaded with GI and Bti is sensitive enough to demonstrate continuous reproductive activity of Cux. quinquefasciatus in the study area throughout the year and to monitor temporal fluctuations in population density.

Prevalence and insecticide susceptibility of dengue vectors in the district of Batticaloa in eastern Sri Lanka

Unprecedented incidences of dengue have been reported in Sri Lanka in recent years. The district of Batticaloa, which was devastated by the 2004 Asian tsunami, is one of the districts affected by dengue. One option to curtail this disease is to implement appropriate vector control measures. A nine-month study was carried out within the Batticaloa Municipal Council limit from April to December 2008. Larval collections were conducted fortnightly using conventional ovitraps for nine months covering the dry and wet seasons. Ovitraps (indoor and outdoor) were placed in 15 randomly selected houses. The collected larvae were brought to the laboratory and reared under laboratory conditions. The larval forms and emerged adults were identified on the basis of reported morphological descriptions. The identified adults of 2–3 d old were exposed to common insecticides following the WHO protocol. During the study period, a total of 10,685 <i>Aedes aegypti</i> and <i>Ae. albopictus</i> mosquitoes were collected, with the former constituting 57% of the total sample. Both species were collected from indoor and outdoor ovitraps, and their prevalence was recorded throughout the study period. A seasonal shift was observed in the density, with <i>Ae. aegypti</i> predominating during the dry season and <i>Ae. albopictus</i> during the wet season. Both species were highly resistant to 4% DDT and susceptible to 0.25% permethrin. The continuous presence of potential dengue vectors may have contributed to the dengue prevalence in the district. Since both species can oviposit in indoor and outdoor ovitraps, public awareness and participation should be promoted in the vector control programme of the Ministry of Health along with continuous vector surveillance.

Oviposition activity of Aedes aegypti L. (Diptera: Culicidae) in responseto different organic infusions

The present study investigates new sources of infusion as an oviposition attractant for Aedes aegypti L. Infusions with fetid and non-fetid odors were compared as an oviposition stimulant. Traps baited with infusions of dehydrated cashew leaves (Anacardium occidentale), potato peels (Solanum tuberosum) and graminea (Panicum maximum) were compared as attractants, and the effect of odor (fetid and unfetid) on attractiveness was tested. Oviposition activity changed significantly according to the concentration and type of infusion (F = 4.1279; gl = 2; P = 0.0231). A larger number of eggs were observed in cups containing 50 percent A. occidentale (non-fetid odor) and 30 percent P. maximum (fetid odor). When compared in the same cage, comparable oviposition was found between A. occidentale and P. maximum. Moreover, approximately 20 percent more eggs were recorded in the infusion without odor when compared to the grass infusion and water. These findings suggest A. occidentale as a new stimulant for use in ovitraps for Aedes surveillance and control, with the benefit of having an agreeable odor.

Do Colour and Surface Area of Ovitrap Influence the Oviposition Behaviour of Aedes aegypti, the Vector of Dengue and DHF.

A newly developed ovitrap made from a fiberglass tray (FGTO) was compared with conventionally used black jar ovitrap (BJO) in field condition in terms of number of eggs received. The number of eggs laid in FGTO was consistently higher than in BJO. The number of eggs collected in FGTO was significantly higher and it was 5-94 times more than that of BJO (t =9.45; p <0.0001). This finding has implication in designing lethal ovitraps for the control of dengue vectors.

Efeito da ovitrampa letal na longevidade de fêmeas de Aedes aegypti (Diptera: Culicidae) / Effect of lethal ovitrap on the longevity of females of Aedes aegypti (Diptera: Culicidae)

A armadilha de oviposição acrescida de inseticida pode funcionar como novo método de controle de fêmeas do mosquito Aedes aegypti. Fêmeas de Aedes aegypti foram colocadas em contato com ovitrampas letais envelhecidas e a mortalidade variou de 60,3 por cento a 100 por cento sendo significativo o efeito do envelhecimento das palhetas impregnadas com deltametrina no percentual de mortalidade.

Oviposition traps with added insecticide may work as a new method for controlling the females of the Aedes aegypti mosquito. Females of Aedes aegypti were placed in contact with lethal ovitraps with aging. The mortality rate ranged from 60.3 percent to 100 percent. The effect of aging the slats impregnated with deltamethrin was significant in relation to the percentage mortality among Aedes aegypti females.

Laboratory and field evaluation of an oviposition trap for Culex quinquefasciatus(Diptera: Culicidae)

An ovitrap (BR-OVT) based on physical and chemical stimuli for attracting gravid Culex quinquefasciatus (Diptera: Culicidae) females was developed and evaluated under laboratory and field conditions. Attractants were assayed using alternative chamber bioassays prior to being used in the BR-OVT oviposition trap. A significant preference of gravid females for sites containing conspecific egg rafts was observed, as a response to the natural oviposition pheromone, as well as for sites treated with the synthetic pheromone erythro-6-acetoxy-5-hexadecanolide. Five- to 20-day old grass infusion was strongly attractive to gravid females for laying eggs. On the other hand, entomopathogenic Bacillus sphaericus (Bs) did not influence the choice of an oviposition site when used in combination with grass infusion and can therefore be used as a larvicide in ovitraps. Results from field trials showed that the BR-OVT with grass infusion and with or without Bs works as a preferred oviposition site for Cx. quinquefasciatus. The BR-OVT was more effective for egg collection when placed indoors and comparison with the number of egg rafts laid in cesspits over 40 days indicates that this very simple ovitrap may be a useful tool for monitoring populations of the most important of the vectors of bancroftian filariasis.