Dancing in the purple rain: color affinity and oviposition choices in Aedes sierrensis (Diptera: Culicidae).

The western tree hole mosquito, Aedes sierrensis (Ludlow) (Diptera: Clucidae), is a pestiferous mosquito with a range extending over the entire pacific seaboard and into portions of the intermountain west. As a peridomestic heartworm vector, it demands at least some level of surveillance to understand its abundance. However, the species is refractory to a majority of conventional vector surveillance approaches for tracking mosquitoes. To find more options for Aedes sierrensis surveillance, a variety of oviposition attractants were evaluated in arena-style choice assays using colony reared adults. A range of infusion treatments (e.g., alfalfa, oak, and beetroot) were examined and then combined with investigations of liquid color as well as ovicup color and entryway position. These studies revealed that Ae. sierrensis have an affinity for purple coloration, plain water, and larger entryway sizes for oviposition cups. A prototype ovicup was 3D-printed using purple filament and multiple types of entryways, and used to re-test infusion waters. No particular attraction differences were detected after normalizing for purple color. Comparisons to black 3D-printed cups yielded surprising observations that male mosquitoes also aggregated on purple cups while females sheltered, but not necessarily oviposited, in black cups. Although this was only a laboratory-based assessment, these studies provide useful information for future field trials of potential oviposition traps for surveillance of Ae. sierrensis.

Evaluation of Modified Autocidal Gravid Ovitraps for Control of Aedes Aegypti in St. Augustine, Florida.

Aedes aegypti is an anthropophilic mosquito that vectors dengue, chikungunya, Zika, and yellow fever viruses. The US Center for Disease Control and Prevention (CDC)'s autocidal gravid ovitraps (AGOs) may facilitate the control of container-inhabiting Aedes mosquitoes and curb arbovirus outbreaks by taking advantage of oviposition-seeking behavior using pesticide-free technology. The AGOs, manufactured by SpringStar Inc., were tested during the summer of 2018 in St. Augustine, FL. A total of 1,718 AGOs were deployed for study in 3 different 40-acre (∼18.2 ha) plots at a density of 5-7 AGOs per house and a coverage of >90% for all AGO test sites. The AGOs were modified using tap water instead of infusion water to reduce the capture of nontarget organisms. Each intervention and reference area was monitored weekly using BioGents Sentinel traps and Sentinel AGOs. Generalized linear mixed models showed that changes to Aedes mosquito populations were more seasonal than treatment driven. Homeowners expressed positivity about traps and believed the traps were both effective and had directly contributed to increased quality of life.

EVALUTION OF MODIFIED AUTOCIDAL GRAVID OVITRAPS FOR CONTROL OF AEDES AEGYPTI IN ST. AUGUSTINE, FLORIDA.

Aedes aegypti is an anthropophilic mosquito that vectors dengue, chikungunya, Zika, and yellow fever viruses. The US Center for Disease Control and Prevention (CDC)'s autocidal gravid ovitraps (AGOs) may facilitate the control of container-inhabiting Aedes mosquitoes and curb arbovirus outbreaks by taking advantage of oviposition-seeking behavior using pesticide-free technology. The AGOs, manufactured by SpringStar Inc., were tested during the summer of 2018 in St. Augustine, FL. A total of 1,718 AGOs were deployed for study in 3 different 40-acre (∼18.2 ha) plots at a density of 5-7 AGOs per house and a coverage of >90% for all AGO test sites. The AGOs were modified using tap water instead of infusion water to reduce the capture of nontarget organisms. Each intervention and reference area was monitored weekly using BioGents Sentinel traps and Sentinel AGOs. Generalized linear mixed models showed that changes to Aedes mosquito populations were more seasonal than treatment driven. Homeowners expressed positivity about traps and believed the traps were both effective and had directly contributed to increased quality of life.

EVALUATION OF THE EFFICIENCY OF BEETROOT PEEL (BETA VULGARIS) IN OVITRAPS AS AN ATTRACTANT FOR SURVEILLANCE OF ARBOVIRUS VECTORS IN THE MUNICIPALITY OF AGRESTINA, STATE OF PERNAMBUCO, BRAZIL.

It is estimated that there are over 500 species of arboviruses worldwide, with more than 150 of them directly associated with human diseases, the majority of which are zoonotic. Among the main arboviruses circulating in Brazil, dengue, Zika, and chikungunya stand out, all transmitted through a common vector, Aedes aegypti. Given this scenario, the development and implementation of more efficient surveillance strategies become urgent. This study aims to compare and evaluate the efficiency of beetroot peel, Beta vulgaris, as an attractant for Ae. aegypti oviposition under field conditions in the municipality of Agrestina, State of Pernambuco, Brazil. Beetroot peel extract is a cheap and accessible source of geosmin, which holds significant potential as an attractant for mosquitoes due to its resemblance to microbial volatiles found in water bodies rich in organic material. During the study period (November 2023 to April 2024), 40 traps were set in each neighborhood, with 20 of each attractant. Two traps were used per property, one following the traditionally used model (beer yeast infusion) and another containing beetroot peel. Overall, in both analyzed neighborhoods (Campo Novo and Cohab), beetroot peel appeared to be a more efficient attractant for the oviposition of culicids. Beetroot peel showed the highest values in egg abundance and in the analyzed indices.

High-resolution mapping of urban Aedes aegypti immature abundance through breeding site detection based on satellite and street view imagery.

Identification of Aedes aegypti breeding hotspots is essential for the implementation of targeted vector control strategies and thus the prevention of several mosquito-borne diseases worldwide. Training computer vision models on satellite and street view imagery in the municipality of Rio de Janeiro, we analyzed the correlation between the density of common breeding grounds and Aedes aegypti infestation measured by ovitraps on a monthly basis between 2019 and 2022. Our findings emphasized the significance (p ≤ 0.05) of micro-habitat proxies generated through object detection, allowing to explain high spatial variance in urban abundance of Aedes aegypti immatures. Water tanks, non-mounted car tires, plastic bags, potted plants, and storm drains positively correlated with Aedes aegypti egg and larva counts considering a 1000 m mosquito flight range buffer around 2700 ovitrap locations, while dumpsters, small trash bins, and large trash bins exhibited a negative association. This complementary application of satellite and street view imagery opens the pathway for high-resolution interpolation of entomological surveillance data and has the potential to optimize vector control strategies. Consequently it supports the mitigation of emerging infectious diseases transmitted by Aedes aegypti, such as dengue, chikungunya, and Zika, which cause thousands of deaths each year.

Comparison of the Trapping Efficacy of Locally Modified Gravid Aedes Trap and Autocidal Gravid Ovitrap for the Monitoring and Surveillance of Aedes aegypti Mosquitoes in Tanzania.

The study assessed the trapping efficacy of locally modified (1) Gravid Aedes Trap (GAT) lined with insecticide-treated net (ITN) as a killing agent and (2) Autocidal Gravid Ovitrap (AGO) with sticky board in the semi-field system (SFS) and field setting. Fully balanced Latin square experiments were conducted to compare GAT lined with ITN vs. AGO, both with either yeast or grass infusion. Biogent-Sentinel (BGS) with BG-Lure and no CO2 was used as a standard trap for Aedes mosquitoes. In the SFS, GAT outperformed AGO in collecting both nulliparous (65% vs. 49%, OR = 2.22, [95% CI: 1.89-2.60], p < 0.001) and gravid mosquitoes (73% vs. 64%, OR = 1.67, [95% CI: 1.41-1.97], p < 0.001). Similar differences were observed in the field. Yeast and grass infusion did not significantly differ in trapping gravid mosquitoes (OR = 0.91, [95% CI: 0.77-1.07], p = 0.250). The use of ITN improved mosquito recapture from 11% to 70% in the SFS. The same trend was observed in the field. Yeast was chosen for further evaluation in the optimized GAT due to its convenience and bifenthrin net for its resistance management properties. Mosquito density was collected when using 4× GATs relative to BGS-captured gravid mosquitoes 64 vs. 58 (IRR = 0.82, [95% CI: 0.35-1.95], p = 0.658) and showed no density dependence. Deployment of multiple yeast-baited GAT lined with bifenthrin net is cost-effective (single GAT < $8) compared to other traps such as BGS ($160).

Temperature Influence on Aedes aegypti Oviposition in the San Joaquin Valley of California.

The establishment and oviposition of Aedes aegypti can vary from one location to another partially due to differing temperature and precipitation. In 2017, Ae. aegypti was first detected in Merced in the Central Valley of California. The objectives of this study were to examine the influence of temperature and precipitation on oviposition of Ae. aegypti, and to determine the beginning and end of the seasonal activity of Ae. aegypti in Merced. The study site consisted of a residential area in the north-east region of Merced where Ae. aegypti was first detected in Merced County. Fifty-four residences were randomly selected as ovitrap sites. Ovitraps were placed at field sites weekly for 12 months, from September 27, 2017, to September 27, 2018. Each week, ovitraps were inspected for the presence of mosquito eggs. Egg counts were used to calculate the following oviposition indices: the ovitrap index (OI) (percent of traps positive) and the egg density index (EDI) (eggs/positive traps). Oviposition occurred primarily from May through October, above a minimum temperature of 10°C, and when almost no rainfall occurred (0.5 mm total). During the year, the percent of positive traps per month ranged from approximately 1.2-67.3%, with highest values in June to October (43.9-67.3%). The highest mean monthly EDI was from July to October (34-44.6) and peaked in October at 44.6 eggs/trap. The EDI values are similar to other locations where Ae. aegypti transmits endemic vector-borne disease. These findings provide baseline data for Ae. aegypti control in Merced and the Central Valley of California.

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.

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.

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.

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.

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.

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.

Dengue vector surveillance and control in Hong Kong in 2008 and 2009.

Dengue vector surveillance programmes were implemented in the community and port areas in Hong Kong Special Administrative Region. Aedes albopictus was the only Aedes vector detected and its distribution was extensive in various areas during the summer months. Aedes aegypti was, however, not detected in any area under surveillance. For community surveillance, the monthly ovitrap indices (MOI) of 2008 and 2009 followed a similar trend as in previous years but were generally lower. The highest ovitrap index recorded in 2008 and 2009 was 37.5% and 48.3% respectively, which were much lower than the highest recorded of 70.9% in 2007. Only two surveyed areas in 2009 had ovitrap indices greater than 20.0% for more than two consecutive months, which was more often seen in 2007. Improvement in the dengue vector situation in the past two years could be attributed to the swift response of the agencies concerned upon getting information on surveillance results via the geographic information system. The public was also informed of the results regularly through the Internet and press releases to create awareness to prevent and control the dengue vector. Health education programmes targeted at different organizations/parties were arranged to promote knowledge about dengue vector prevention and control.