Mosquito Eggs Research Articles

Response of Mosquitoes Associated with Estuarine Wetlands to Bushfire in Australia.

The response of mosquitoes to bushfire is poorly understood. During the 2019-20 summer, many regions of Australia were impacted by devastating bushfires. An area of estuarine and brackish-water wetlands alongside the Georges River, Sydney, New South Wales, was burned in January 2020. Mosquito populations within the area were monitored as part of the local authority's mosquito management program, providing a unique opportunity to record the response of key mosquitoes of pest and public health concern to bushfire. Ground pools within a tidally influenced swamp oak forest dominated by Casuarina glauca and associated wetlands dominated by Phragmites australis and Bolboschoenus spp. had been identified as suitable habitat for a range of mosquitoes, including Aedes alternans, Ae. vigilax, and Verrallina funerea. Surveys of immature stages of mosquitoes within recently burned habitats inundated by tides demonstrated that mosquito eggs survived the direct and indirect impacts of fire and immature stages successfully completed development as reflected in concomitant changes in adult mosquito populations following the bushfire. This unique observation has implications for mosquito management following bushfire in Australia and internationally.

Efficacy of Intelligent Mosquito System (I.M.O.S) with Xmos Mini Aerosol Against Aedes in 17th College, Universiti Putra Malaysia

This study reports the efficacy of I.M.O.S (Intelligent Mosquito System) by using Xmos mini aerosol in reducing Aedes mosquito population in 17th College, Universiti Putra Malaysia (UPM). Prior to the experiment, the Aedes mosquito population was determined in all blocks of the 17th College, UPM. The I.M.O.S. was installed above the entrance door of the hall and two rooms and was set to automatically spray at 6.30 am and 4.00 pm every day. No intervention was used in the control house. Adult efficacy study was conducted by placing 20 Aedes mosquitoes in each cage and was hung at a distance of 10 feet from the I.M.O.S. The mortality caused by I.M.O.S throughout the exposed two hours and after 24 hours of exposure was recorded. The number mosquito eggs population were calculated throughout the installation of I.M.O.S. Data were analysed using two-way ANOVA and paired T-test, respectively. The mean number of Aedes mosquito eggs and ovitraps index showed no significant difference (p>0.05) between control and treatment blocks. There were significant differences (p<0.05) in the percentage of knockdown of adult Aedes mosquitoes (10, 20, 30, 60 and 120 minutes after exposure) and the mortality of adult Aedes mosquitoes after 24 hours exposure. Nano and slow-release technology of the I.M.O.S with Xmos mini aerosol proved that this type of intervention can kill adult Aedes mosquitoes. Thus, it is a potential intervention for vector control and management.

DAYA TETAS TELUR NYAMUK Aedes aegypti PADA TIGA JENIS AIR PERINDUKAN DI KELURAHAN MEDONO KOTA PEKALONGAN

The <em>Aedes aegypti</em> mosquito lays its eggs in calm and clear water. People often collect water for daily needs which is placed outside or inside the house, water comes from tap water, rainwater, and well water, provide a good place for <em>Aedes aegypti </em>to breed. The <em>Aedes aegypti</em> as a vector of the Dengue Virus and others. The prevalence of Dengue Fever in Pekalongan City in 2017, as many as 44 cases of DHF in the Medono Community Health Center area. The purpose of this study was to determine the hatchability of <em>Aedes aegypti</em> eggs in the well water, tap water, and rainwater in Medono Village, Pekalongan City. The research was carried out at the Research and Development Center for Disease Vector and Reservoir Research Laboratory (B2P2VRP) Salatiga. The sample consisted of 540 eggs of <em>Aedes aegypti. </em>This research is descriptive, which makes observations and examinations in the laboratory by inserting <em>Aedes aegypti</em> eggs into three types of water, with nine replications for each type of water, each glass filled with 20 mosquito eggs, and observed for 24 hours. Research also measures water temperature and pH. The results show the average number of mosquito eggs hatched in well water as many as 6.89 (34.45%), rainwater 4.44 (22.2%), and tap water 2.67 (13.35%). The pH of the well water is 7.56, rainwater is 7, and tap water is 6. The temperature of the three types of water is the same, which is 25<sup>O</sup> C. The conclusion of this research is the hatchability of <em>Aedes aegypti</em> eggs in well water as many as 6.89 (34.45%), rainwater 4.44 (22.2%) and tap water 2.67 (13.35%). Tap water with a lower pH has a lower hatchability of <em>Aedes aegypti</em> eggs.

Increased size and energy reserves in diapausing eggs of temperate Aedes aegypti populations

Many insects overwinter in diapause, a pre-programmed anticipated response to unfavorable environmental conditions, often induced by a short-day photoperiod. Diapause involves morphological changes and increased energy stores required for metabolic demands during winter. In diapausing mosquito eggs, the accumulation of lipids plays an important role, because these molecules are the primary fuel consumed during embryogenesis and pharate larvae metabolism, and have a key role in egg desiccation resistance. The supposed inability of the mosquito Aedes aegypti to lay diapausing eggs has been recently challenged by a study on a temperate population, which showed that the inhibition of egg hatching in response to short days is possible in this species. Thus, the aim of the present study was to assess the effects of parental photoperiod on embryonic diapause-related traits, such as the triglyceride content and size of eggs laid, of two populations whose localities of origin differ in their winter length. Two colonies were maintained for each population: one under a Short-Day Photoperiod (SD: 10 h:14 h – Light:Dark) and the other under a Long-Day Photoperiod (LD: 14 h:10 h – Light:Dark). The eggs obtained from each combination of population and light treatment were used for size measurement (length, width and volume) and for the quantification of triglyceride content. Egg size showed differences between photoperiod treatments, with larger width and volume in eggs from the SD treatment. Remarkably, eggs from the SD treatment accumulated twice as many triglycerides as those from the LD treatment. Also, the eggs derived from the population having the longer winter accumulated larger amounts of triglycerides. The higher lipid content is probably contributing to a better survival during the cold season in both populations. The photoperiod-induced response in egg size and amount of triglycerides observed in this study support the hypothesis that the Ae. aegypti populations studied are able to lay diapausing eggs, a fact that provides physiological bases for the further expansion of this species to colder regions.

Colonization and Various Parameters Affecting Egg Hatch and Development of the Old Balara Strain (Philippines), Aedes aegypti

Aedes aegypti strain obtained from field collections in Old Balara, Quezon City, Philippines was colonized at the Department of Science and Technology–Philippine Nuclear Research Institute (DOST-PNRI) laboratory. The number of eggs and their weight followed a significant linear relationship for the Ae. aegypti colony. Storing the hatching solution composed of nutrient broth (NB) and brewer’s yeast (BY) longer for at least 16 h hatched the mosquito fastest within 4h. Among the different ages tested, 2-wk-old eggs had the highest hatch rate. After collecting eggs from rearing cages, eggs for 6 wk still produced a high hatch rate and pupal recovery. Mosquito eggs can be effectively stored in cup and ziplock with a hatch rate of at least 77% on the third week, and at least 71% on the fourth week. Eggs stored in plastic cups can be best stored at 17–20 °C in the incubator 4 wk without a decrease in hatch rate. Eggs at these temperatures still produced about 50% egg hatch even until 3 mo.

Impact of recent climate extremes on mosquito-borne disease transmission in Kenya.

Climate change and variability influence temperature and rainfall, which impact vector abundance and the dynamics of vector-borne disease transmission. Climate change is projected to increase the frequency and intensity of extreme climate events. Mosquito-borne diseases, such as dengue fever, are primarily transmitted by Aedes aegypti mosquitoes. Freshwater availability and temperature affect dengue vector populations via a variety of biological processes and thus influence the ability of mosquitoes to effectively transmit disease. However, the effect of droughts, floods, heat waves, and cold waves is not well understood. Using vector, climate, and dengue disease data collected between 2013 and 2019 in Kenya, this retrospective cohort study aims to elucidate the impact of extreme rainfall and temperature on mosquito abundance and the risk of arboviral infections. To define extreme periods of rainfall and land surface temperature (LST), we calculated monthly anomalies as deviations from long-term means (1983-2019 for rainfall, 2000-2019 for LST) across four study locations in Kenya. We classified extreme climate events as the upper and lower 10% of these calculated LST or rainfall deviations. Monthly Ae. aegypti abundance was recorded in Kenya using four trapping methods. Blood samples were also collected from children with febrile illness presenting to four field sites and tested for dengue virus using an IgG enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). We found that mosquito eggs and adults were significantly more abundant one month following an abnormally wet month. The relationship between mosquito abundance and dengue risk follows a non-linear association. Our findings suggest that early warnings and targeted interventions during periods of abnormal rainfall and temperature, especially flooding, can potentially contribute to reductions in risk of viral transmission.

Rapamycin inhibits pathogen transmission in mosquitoes by promoting immune activation.

Repeated blood meals provide essential nutrients for mosquito egg development and routes for pathogen transmission. The target of rapamycin, the TOR pathway, is essential for vitellogenesis. However, its influence on pathogen transmission remains to be elucidated. Here, we show that rapamycin, an inhibitor of the TOR pathway, effectively suppresses Plasmodium berghei infection in Anopheles stephensi. An. stephensi injected with rapamycin or feeding on rapamycin-treated mice showed increased resistance to P. berghei infection. Exposing An. stephensi to a rapamycin-coated surface not only decreased the numbers of both oocysts and sporozoites but also impaired mosquito survival and fecundity. Transcriptome analysis revealed that the inhibitory effect of rapamycin on parasite infection was through the enhanced activation of immune responses, especially the NF-κB transcription factor REL2, a regulator of the immune pathway and complement system. Knockdown of REL2 in rapamycin-treated mosquitoes abrogated the induction of the complement-like proteins TEP1 and SPCLIP1 and abolished rapamycin-mediated refractoriness to Plasmodium infection. Together, these findings demonstrate a key role of the TOR pathway in regulating mosquito immune responses, thereby influencing vector competence.

Infertility and fecundity loss of Wolbachia-infected Aedes aegypti hatched from quiescent eggs is expected to alter invasion dynamics.

The endosymbiotic bacterium Wolbachia shows viral blocking in its mosquito host, leading to its use in arboviral disease control. Releases with Wolbachia strains wMel and wAlbB infecting Aedes aegypti have taken place in several countries. Mosquito egg survival is a key factor influencing population persistence and this trait is also important when eggs are stored prior to releases. We therefore tested the viability of mosquitoes derived from Wolbachia wMel and wAlbB-infected as well as uninfected eggs after long-term storage under diurnal temperature cycles of 11–19°C and 22–30°C. Eggs stored at 11–19°C had higher hatch proportions than those stored at 22–30°C. Adult Wolbachia density declined when they emerged from eggs stored for longer, which was associated with incomplete cytoplasmic incompatibility (CI) when wMel-infected males were crossed with uninfected females. Females from stored eggs at both temperatures continued to show perfect maternal transmission of Wolbachia, but storage reduced the fecundity of both wMel and wAlbB-infected females relative to uninfected mosquitoes. Furthermore, we found a very strong negative impact of the wAlbB infection on the fertility of females stored at 22–30°C, with almost 80% of females hatching after 11 weeks of storage being infertile. Our findings provide guidance for storing Wolbachia-infected A. aegypti eggs to ensure high fitness adult mosquitoes for release. Importantly, they also highlight the likely impact of egg quiescence on the population dynamics of Wolbachia-infected populations in the field, and the potential for Wolbachia to suppress mosquito populations through cumulative fitness costs across warm and dry periods, with expected effects on dengue transmission.

Adulticidal Efficacy and Sublethal Effects of Metofluthrin in Residual Insecticide Blends Against Wild Aedes albopictus (Diptera: Culicidae).

Field development for optimizing the use patterns of spatial repellents are an ongoing research need. To investigate volatile pyrethroids in blends containing multiple active ingredients, metofluthrin was formulated into a vegetation spray for application to foliage and mosquito harborage. Metofluthrin was compared by itself and in combination with Sector (permethrin), Hyperion (sumithrin), Onslaught Fast Cap (s-fenvalerate, prallethrin), and against a benchmark for comparison, OneGuard (λ-cyhalothrin, prallethrin, pyriproxyfen). Field sites with established Aedes albopictus (Skuse) (Diptera: Culicidae) populations were allocated as control and treatment and surveilled with both adult traps and oviposition cups before and after treatment. Adult mosquito reductions were consistently higher over 4 wk in the combination treatments and were comparable to OneGuard. In contrast, efficacy provided by metofluthrin alone or the standalone existing product (Sector, Hyperion, Onslaught) by were consistently less effective than OneGuard and the comparative blends. Additionally, poorly melanized and collapsing eggs were identified from mosquito adults collected at treated field sites. A 20-50% significant decrease in nonviable mosquito eggs, a 50% or more reduction in total eggs and an 80% or more reduction in adult mosquitoes collected at the local field sites was demonstrated across all metofluthrin-containing treatments. Metofluthrin applications both supplemented the adulticidal control of the selected pyrethroid-containing products and provided significant reduction in egg laying frequency and viability during monitoring of areas adjacent to the treated vegetation. Metofluthrin, and possibly other volatile ingredients, appears to have complex interactions for mosquito control in the field and could be unique as a supporting ingredient to other insecticides.

Characterization of Pyrethroid Resistance Mechanisms in Aedes aegypti from the Florida Keys.

ABSTRACTThe status of insecticide resistance in Aedes aegypti is of concern in areas where Aedes-borne arboviruses like chikungunya, dengue, and Zika occur. In recent years, outbreaks involving these arboviruses have occurred, for which vaccines do not exist; therefore, disease prevention is only through vector control and personal protection. Aedes aegypti are present on every inhabited island within the Florida Keys. The resistance status of Ae. aegypti in the Florida Keys was assessed to guide knowledge of the best choice of chemical for use during an outbreak. Mosquito eggs were collected using ovitraps placed on Key West, Stock Island, Vaca Key, Upper Matecumbe Key, Plantation Key, and Key Largo. Bottle bioassays were conducted at the Florida Keys Mosquito Control District using Biomist® 30+30 (Clarke Mosquito Control Products, Inc., Roselle, IL). Further bottle testing using malathion and permethrin occurred at the CDC, Fort Collins, CO, in addition to molecular and biochemical assays. Levels of resistance varied between islands with different underlying mechanisms present. Resistance was seen to Biomist® 30+30 but not to permethrin, indicating that piperonyl butoxide (PBO) or the inert ingredients may be involved in resistance. No study has been conducted to date examining the role of PBO in resistance. Key Largo was treated the most with adulticides and expressed the highest levels of alpha and beta esterases, oxidases, glutathione-S-transferases, and frequency of the V1016I knockdown mutation from all sites tested. Knowledge of localized resistance and underlying mechanisms helps in making rational decisions in selection of appropriate and effective insecticides.

APPLICATION OF LARVITRAP AND OVITRAP TO CONTROL Aedes sp. IN DHF ENDEMIC AREAS

Alternative mosquito vector control at this time that is cheap, practical and relatively safe to the environment is needed by developing countries such as Indonesia.One of the methods of controlling Aedes sp without insecticides is the use of larvae traps (larvitrap). The working principle of larvitrap is that the eggs trapped in the tool The incidence rate (IR) of Dengue Hemorrhagic Fever per 100.000 population in Central Java in the last five years is as follows: 2011 amounted to 15,27 in 2012 amounted to 19,29 in 2013 amounted to 45,52 in 2014 amounted to 32,95 and years 2015 amounted to 34,87. Since 2010 DHF has spread to all districts / cities in Central Java. Larvitrap and ovitrap are tools that can be used as traps for Aedes sp. Both of these tools can be used with additional attractants which can serve to attract the attention of Aedes sp. in order to lay eggs on the tool. Larvae that hatch from eggs in the larvitrap eventually cannot become adults and will die. Mosquito eggs trapped in the ovitrap can be destroyed so that they do not develop into adult mosquitoes. The research objective was to determine the effectiveness of using larvitrap and ovitrap as a control tool for Aedes sp (DHF vector).The research method used is experimental research. The research location is in the Banyumas Regency area. Larvitrap made of plastic jars and pralon was painted black and modified using gauze on the top. Ovitrap from plastic cups was painted black and given an ovistrip. Larvitrap and ovitrap were placed in DHF endemic areas. After the larvitrap and ovitrap are taken, the number of trapped Aedes sp and the larvitrap / ovitrap index is calculated. Furthermore, analyzed the effectiveness of using larvitrap and ovitrap as a means of controlling mosquitoes Aedes sp.The results showed that the larvitrap index in the larvitrap installation in Pandak Village was 60%, while in Mersi Village it was 56,7%. The ovitrap index in the ovitrap installation in Pandak Village was 36,7%, while in Mersi Village it was 33,3%. The number of larvae trapped in the larvitrap installation in Pandak Village were 832 larvae, while in Mersi Village there were 985 larvae. The number of eggs trapped in the ovitrap installation in Pandak Village were 518 eggs, while in Mersi Village there were 811 eggs.The conclusion of this research is that larvitrap is more effective to control Aedes sp than ovitrap. The community is advised to use larvitrap as a tool to control the Aedes sp (DHF vector.

Egg data validation in quantitative monitoring of Aedes albopictus in Emilia-Romagna region, Italy

ABSTRACT The monitoring of Aedes urban species is usually conducted by ovitraps, which can provide a good estimate of population density at low cost and relatively easy management. When the monitoring network is managed by many operators, as in the case of the Emilia-Romagna regional plan, it becomes necessary to develop a quality control methodology capable of highlighting the possible data incoherency and ensuring that the monitoring system provides reliable data. This paper presents the procedure applied in the egg counting phase as developed in Emilia-Romagna in order to check the data quality and validate the data before being included in the database. Several steps have been identified and protocols developed to serve quality control such as training of technicians and intralaboratory quality check, daily random double counting of Masonite paddles and interlaboratory periodic comparison. The qualitative test showed that all operators were able to distinguish Aedes albopictus eggs from other mosquito species eggs. The quantitative test showed significant differences between the 11 operators, with a relative error resulting in the range of 0.1–25.8%. The daily internal double counting of randomly extracted Masonite slides was performed by the coordinator showing a relative error in the range 2.47–2.63% without statistical differences, confirming a good alignment of the operators with the coordinator throughout the monitoring period. The interlaboratory comparison trial produced an average relative error of 7.20% showing a sufficient alignment between the three laboratories. Moreover a new time-saving methods in egg counting was developed and tested in real condition.

Aedes Albopictus (Diptera: Culicidae) Susceptibility Status to Agrochemical Insecticides Used in Durian Planting Systems in Southern Thailand

High rates of dengue morbidity occur in southern Thailand. The intensive application of insecticides in orchards could affect not only agricultural insect pests, but also nontarget mosquitoes or beneficial insects. In this study, the type and quantity of insecticides commonly used across durian plantations in southern Thailand were characterized, along with the population density of Aedes albopictus (Skuse) (Diptera: Culicidae). Our primary aim was to determine the susceptibility status of field-derived Ae. albopictus to typical application concentrations of four agrochemical insecticides; cypermethrin, chlorpyrifos, carbaryl, and imidacloprid. Mosquito eggs were collected from durian cultivation sites in five provinces in southern Thailand and used to generate adults for susceptibility tests. The cultivation sites were categorized into three groups based on insecticide application: intensive application of insecticides, low application of insecticides, and no application of insecticides. Twenty ovitraps were deployed for at least three consecutive days at each study site to collect mosquito eggs and to determine Ae. albopictus population density. WHO tube assays were used to determine the susceptibility of adult mosquitoes derived from field-collected eggs to selected insecticides. This represents the first report of the susceptibility status of Ae. albopictus from durian orchards in southern Thailand to agrochemical insecticides. Results showed complete susceptibility of these Ae. albopictus to chlorpyrifos, but reduced mortality following exposure to λ-cyhalothrin, carbaryl, and imidacloprid, which is suggestive of the development of resistance. These findings provide new insights into the status of insecticide susceptibility in Ae. albopictus populations, with important implications for mosquito and mosquito-borne disease control in Thailand.

Prolonged hypoxia induced melanotic pseudotumors in the larvae of blood-sucking mosquitoes

It was found that the presence of mosquito eggs in artificially created conditions of prolonged hypoxia causes the appearance of numerous melanotic pseudotumors in the larvae hatching from such eggs. In the cells of melanotic pseudotumors multilayer concentric membrane-like structures were found in the cytoplasm. In the immediate vicinity of such membranes, small spherical virus-like particles (VLP) with a diameter of about 30 nm were observed. The possible role of hypoxia in the development of melanotic pseudotumors of mosquito larvae is discussed

Culex pipiens and Culex restuans egg rafts harbor diverse bacterial communities compared to their midgut tissues

BackgroundThe bacterial communities associated with mosquito eggs are an essential component of the mosquito microbiota, yet there are few studies characterizing and comparing the microbiota of mosquito eggs to other host tissues.MethodsWe sampled gravid female Culex pipiens L. and Culex restuans Theobald from the field, allowed them to oviposit in the laboratory, and characterized the bacterial communities associated with their egg rafts and midguts for comparison through MiSeq sequencing of the 16S rRNA gene.ResultsBacterial richness was higher in egg rafts than in midguts for both species, and higher in Cx pipiens than Cx. restuans. The midgut samples of Cx. pipiens and Cx. restuans were dominated by Providencia. Culex pipiens and Cx. restuans egg rafts samples were dominated by Ralstonia and Novosphingobium, respectively. NMDS ordination based on Bray-Curtis distance matrix revealed that egg-raft samples, or midgut tissues harbored similar bacterial communities regardless of the mosquito species. Within each mosquito species, there was a distinct clustering of bacterial communities between egg raft and midgut tissues.ConclusionThese findings expand the list of described bacterial communities associated with Cx. pipiens and Cx. restuans and the additional characterization of the egg raft bacterial communities facilitates comparative analysis of mosquito host tissues, providing a basis for future studies seeking to understand any functional role of the bacterial communities in mosquito biology.

Induced Hatching of Quiescent Aedes aegypti (Diptera: Culicidae) Eggs by Labile Glutathione-Stabilizable Compounds From Yeast Extract.

Aedes aegypti (Linnaeus, 1762) is the insect vector that transmits several deadly human diseases. Although the egg stage is an important phase of its life cycle, the biology of mosquito egg remains poorly understood. Here, we report our investigations on the chemical factors that induced hatching of Ae. aegypti eggs. Commercial yeast extracts were able to increase egg hatching rate in a dose-dependent manner, with a hatching rate that ranged from approximately 10% with 1 g/liter to 80% with 20 g/liter of yeast extract. Notably, the addition of glutathione, a reducing agent that showed no significant effect on egg hatching by itself, enhanced and stabilized the activity of yeast extract for at least 70 h. Because dissolved oxygen in different treatments was maintained at high levels in a narrow range (92-95%), we proposed that yeast extract contains hatching inducing compound (HIC) which is able to trigger egg hatching independent of dissolved oxygen level. The HIC in yeast extract could prove to be a potential starting point to design an effective tool to forcefully induce mosquito eggs to hatch under unfavorable conditions, functioning as a novel method for vector control.

Exposure to nanoceria impacts larval survival, life history traits and fecundity of Aedes aegypti.

Effectively controlling vector mosquito populations while avoiding the development of resistance remains a prevalent and increasing obstacle to integrated vector management. Although, metallic nanoparticles have previously shown promise in controlling larval populations via mechanisms which are less likely to spur resistance, the impacts of such particles on life history traits and fecundity of mosquitoes are understudied. Herein, we investigate the chemically well-defined cerium oxide nanoparticles (CNPs) and silver-doped nanoceria (AgCNPs) for larvicidal potential and effects on life history traits and fecundity of Aedes (Ae.) aegypti mosquitoes. When 3rd instar larvae were exposed to nanoceria in absence of larval food, the mortality count disclosed significant activity of AgCNPs over CNPs (57.8±3.68% and 17.2±2.81% lethality, respectively) and a comparable activity to Ag+ controls (62.8±3.60% lethality). The surviving larvae showed altered life history traits (e.g., reduced egg hatch proportion and varied sex ratios), indicating activities of these nanoceria beyond just that of a larvicide. In a separate set of experiments, impacts on oocyte growth and egg generation resulting from nanoceria-laced blood meals were studied using confocal fluorescence microscopy revealing oocytes growth-arrest at 16-24h after feeding with AgCNP-blood meals in some mosquitoes, thereby significantly reducing average egg clutch. AgCNPs caused ~60% mortality in 3rd instar larvae when larval food was absent, while CNPs yielded only ~20% mortality which contrasts with a previous report on green-synthesized nanoceria and highlights the level of detail required to accurately report and interpret such studies. Additionally, AgCNPs are estimated to contain much less silver (0.22 parts per billion, ppb) than the amount of Ag+ needed to achieve comparable larvicidal activity (2.7 parts per million, ppm), potentially making these nanoceria ecofriendly. Finally, this work is the first study to demonstrate the until-now-unappreciated impacts of nanoceria on life history traits and interference with mosquito egg development.

A qualitative study of community perspectives surrounding cleaning practices in the context of Zika prevention in El Salvador: implications for community-based Aedes aegypti control

BackgroundIn El Salvador, Aedes aegypti mosquitoes transmitting Zika and other arboviruses use water storage containers as important oviposition sites. Promotion of water storage container cleaning is a key element of prevention programs. We explored community perceptions surrounding cleaning practices among pregnant women, male partners of pregnant women, and women likely to become pregnant.MethodsResearchers conducted 11 focus groups and 12 in-depth interviews which included individual elicitations of Zika prevention measures practiced in the community. Focus group participants rated 18 images depicting Zika-related behaviors according to effectiveness and feasibility in the community context, discussed influencing determinants, voted on community intentions to perform prevention behaviors, and performed washbasin cleaning simulations. In-depth interviews with male partners of pregnant women used projective techniques with images to explore their perceptions on a subset of Zika prevention behaviors.ResultsGeneral cleaning of the home, to ensure a healthy environment, was a strong community norm. In this context, participants gave water storage container cleaning a high rating, for both its effectiveness and feasibility. Participants were convinced that they cleaned their water storage containers effectively against Zika, but their actual skills were inadequate to destroy Aedes aegypti eggs. A further constraint was the schedule of water availability. Even during pregnancy, male partners rarely cleaned water storage containers because water became available in homes when they were at work. Furthermore, prevailing gender norms did not foster male participation in domestic cleaning activities. Despite these factors, many men were willing to provide substantial support with cleaning when their partners were pregnant, in order to protect their family.ConclusionsBehavior change programs for the prevention of Zika and other arboviruses need to improve community members’ mosquito egg destruction skills rather than perpetuate the promotion of non-specific cleaning in and around the home as effective. Egg elimination must be clearly identified as the objective of water storage container maintenance and programs should highlight the effective techniques to achieve this goal. In addition, programs must build the skills of family members who support pregnant women to maintain the frequency of effective egg destruction in all water storage containers of the home.

Unlike Zika, Chikungunya virus interferes in the viability of Aedes aegypti eggs, regardless of females\u2019 age

Chikungunya and Zika are arboviruses transmitted by the mosquito Aedes aegypti. Mosquito fecundity and egg viability are important parameters of vectorial capacity. Here we aim to understand, comparatively, the effects of Chikungunya virus (CHIKV) and Zika virus (ZIKV) infections on the fecundity and fertility of young and old Aedes aegypti females. Using artificial infection blood feeding experiments we observed that both CHIKV and ZIKV do not alter the number of eggs laid when compared to uninfected females, although the egg fertility significantly decreases in both young and old CHIKV-infected females. There is an upward trend of null females (infertile females) from 2.1% in young to 6.8% in old ZIKV-infected females. Together, our data revealed that CHIKV and ZIKV affects differently Ae. aegypti physiology, that may be related to different viral spread in nature.

Working towards a Co-Ordinated Approach to Invasive Mosquito Detection, Response and Control in the UK.

The United Kingdom (UK) has reported a single detection of the eggs of the invasive mosquito vector Aedes albopictus in each of the three years from 2016 to 2018, all in southeast England. Here, we report the detection of mosquito eggs on three occasions at two sites in London and southeast England in September 2019. Mosquito traps were deployed at 56 sites, in England, Scotland, Wales, and Northern Ireland, as part of a coordinated surveillance programme with local authorities, Edge Hill University, and government departments. Response to each detection was coordinated by Public Health England’s (PHE) local health protection teams, with technical support from PHE’s Medical Entomology group, and control conducted by the respective local authority. Control, including source reduction and larviciding, was conducted within a 300 metre radius of the positive site. The response followed a National Contingency Plan for Invasive Mosquitoes: Detection of Incursions. Although the response to these incidents was rapid and well co-ordinated, recommendations are made to further develop mosquito surveillance and control capability for the UK.