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•The effective control of Anopheles vectors plays a key role in any malaria management program.•Most National Malaria Control Programs in Africa still rely to IRS and LLINs.•IRS and ...LLINs reduce malaria incidence but have little impact on malaria prevalence.•Outdoor transmission and insecticide resistance threaten the efficacy of LLINs and IRS.•This review discussed challenges and trends in malaria vector control research.
The effective and eco-friendly control of Anopheles vectors plays a key role in any malaria management program. Integrated Vector Management (IVM) suggests making use of the full range of vector control tools available. The strategies for IVM require novel technologies to control outdoor transmission of malaria. Despite the wide number of promising control tools tested against mosquitoes, current strategies for malaria vector control used in most African countries are not sufficient to achieve successful malaria control. The majority of National Malaria Control Programs in Africa still rely on indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs). These methods reduce malaria incidence but generally have little impact on malaria prevalence. In addition to outdoor transmission, growing levels of insecticide resistance in targeted vectors threaten the efficacy of LLINs and IRS. Larvicidal treatments can be useful, but are not recommended for rural areas. The research needed to improve the quality and delivery of mosquito vector control should focus on (i) optimization of processes and methods for vector control delivery; (ii) monitoring of vector populations and biting activity with reliable techniques; (iii) the development of effective and eco-friendly tools to reduce the burden or locally eliminate malaria and other mosquito-borne diseases; (iv) the careful evaluation of field suitability and efficacy of new mosquito control tools to prove their epidemiological impact; (v) the continuous monitoring of environmental changes which potentially affect malaria vector populations; (vi) the cooperation among different disciplines, with main emphasis on parasitology, tropical medicine, ecology, entomology, and ecotoxicology. A better understanding of behavioral ecology of malaria vectors is required. Key ecological obstacles that limit the effectiveness of vector control include the variation in mosquito behavior, development of insecticide resistance, presence of behavioral avoidance, high vector biodiversity, competitive and food web interactions, lack of insights on mosquito dispersal and mating behavior, and the impact of environmental changes on mosquito ecological traits. Overall, the trans-disciplinary cooperation among parasitologists and entomologists is crucial to ensure proper evaluation of the epidemiological impact triggered by novel mosquito vector control strategies.
About the Authors: André B. B. Wilke * E-mail: axb1737@med.miami.edu Affiliation: Department of Public Health Sciences, Miller School of Medicine, University of Miami, Miami, Florida, United States ...of America ORCID logo http://orcid.org/0000-0002-6629-7666 Giovanni Benelli Affiliation: Department of Agriculture, Food and Environment, University of Pisa, via del Borghetto, Pisa, Italy ORCID logo http://orcid.org/0000-0001-8971-6010 John C. Beier Affiliation: Department of Public Health Sciences, Miller School of Medicine, University of Miami, Miami, Florida, United States of America ORCID logo http://orcid.org/0000-0003-0095-4130 Citation: Wilke ABB, Benelli G, Beier JC (2020) Beyond frontiers:
Invasive mosquitoes of epidemiological importance, such as Aedes aegypti (L.), A. albopictus (Skuse), and Culex quinquefasciatus Say, are more likely to adapt and thrive in urban environments in low-latitude parts of the world in comparison with native species 3,4.
...invasive species often benefit from biotic homogenization processes and from the reduction in overall biodiversity by being able to increase their range and abundance in the process 3,5–7.
...it is currently unknown what mechanisms are employed by invasive mosquito species to disperse, establish, and thrive in urban environments.
...environmental and physiological features that trigger and support mosquito dispersal are also yet to be identified.
Suggested framework for future research on the development of control strategies to prevent the invasion, establishment, and colonization of new areas by alien mosquito vectors * Development of basic information on how and why invasive vector species are becoming locally abundant in urban habitats. * Development of profiles of basic ecology and behavior for new and neglected invasive mosquito species to clarify their potential importance as vectors. * Increase in awareness about the potential presence of invasive mosquito species to avoid their underestimation or even failure in detecting them due to misidentification of specimens or surveillance strategies disregarding their habitats. * Assessment of current and future risks to determine if some invasive species should be considered a higher priority for vector control operations.
•There is an urgent need to understand the ecology of disease vectors to implement control strategies.•We introduce the Special Issue “Merging ecology and control of disease vectors”•The collection ...of papers should foster strategies of disease vector control
This is the introductory paper to the special issue "Merging ecology and control of vectors as a strategy to reduce zoonotic risks: an introduction to the Special Issue"
Global increases in temperatures and urbanization are impacting the epidemiology of mosquito-borne diseases. Urbanization processes create suitable habitats for vector mosquitoes in which there are a ...reduced number of predators, and human hosts are widely available. We hypothesize that mosquito vector species, especially Aedes aegypti, are locally concentrated primarily in those specific habitats at the neighborhood levels that provide suitable conditions and environmental resources needed for mosquito survival. Determining how mosquito vector species composition and abundance depend on environmental resources across habitats addresses where different types of vector control need to be applied. Therefore, our goal was to analyze and identify the most productive aquatic habitats for mosquitoes in Miami-Dade County, Florida. Immature mosquito surveys were conducted throughout Miami-Dade County from April 2018 to June 2019, totaling 2,488 inspections. Mosquitoes were collected in 76 different types of aquatic habitats scattered throughout 141 neighborhoods located in the urbanized areas of Miami-Dade County. A total of 44,599 immature mosquitoes were collected and Ae. aegypti was the most common and abundant species, comprising 43% of all specimens collected. Aedes aegypti was primarily found in buckets, bromeliads, and flower pots, concentrated in specific neighborhoods. Our results showed that aquatic habitats created by anthropogenic land-use modifications (e.g., ornamental bromeliads, buckets, etc.) were positively correlated with the abundance of Ae. aegypti. This study serves to identify how vector mosquitoes utilize the resources available in urban environments and to determine the exact role of these specific urban features in supporting populations of vector mosquito species. Ultimately, the identification of modifiable urban features will allow the development of targeted mosquito control strategies optimized to preventatively control vector mosquitoes in urban areas.
Integrated vector management (IVM) is defined as "a rational decision-making process for the optimal use of resources for vector control" and includes five key elements: 1) evidence-based ...decision-making, 2) integrated approaches 3), collaboration within the health sector and with other sectors, 4) advocacy, social mobilization, and legislation, and 5) capacity-building. In 2004, the WHO adopted IVM globally for the control of all vector-borne diseases. Important recent progress has been made in developing and promoting IVM for national malaria control programmes in Africa at a time when successful malaria control programmes are scaling-up with insecticide-treated nets (ITN) and/or indoor residual spraying (IRS) coverage. While interventions using only ITNs and/or IRS successfully reduce transmission intensity and the burden of malaria in many situations, it is not clear if these interventions alone will achieve those critical low levels that result in malaria elimination. Despite the successful employment of comprehensive integrated malaria control programmes, further strengthening of vector control components through IVM is relevant, especially during the "end-game" where control is successful and further efforts are required to go from low transmission situations to sustained local and country-wide malaria elimination. To meet this need and to ensure sustainability of control efforts, malaria control programmes should strengthen their capacity to use data for decision-making with respect to evaluation of current vector control programmes, employment of additional vector control tools in conjunction with ITN/IRS tactics, case-detection and treatment strategies, and determine how much and what types of vector control and interdisciplinary input are required to achieve malaria elimination. Similarly, on a global scale, there is a need for continued research to identify and evaluate new tools for vector control that can be integrated with existing biomedical strategies within national malaria control programmes. This review provides an overview of how IVM programmes are being implemented, and provides recommendations for further development of IVM to meet the goals of national malaria control programmes in Africa.
Current tools and strategies are not sufficient to reliably address threats and outbreaks of arboviruses including Zika, dengue, chikungunya, and yellow fever. Hence there is a growing public health ...challenge to identify the best new control tools to use against the vector Aedes aegypti. In this study, we investigated Ae. aegypti sugar feeding strategies in Bamako, Mali, to determine if this species can be controlled effectively using attractive toxic sugar baits (ATSB).
We determined the relative attraction of Ae. aegypti males and females to a variety of sugar sources including flowers, fruits, seedpods, and honeydew in the laboratory and using plant-baited traps in the field. Next, we observed the rhythm of blood feeding versus sugar feeding activity of Ae. aegypti in vegetation and in open areas. Finally, we studied the effectiveness of spraying vegetation with ATSB on Ae. aegypti in sugar rich (lush vegetation) and in sugar poor (sparse vegetation) urban environments.
Male and female laboratory sugar feeding rates within 24 h, on 8 of 16 plants offered were over 80%. The survival rates of mosquitoes on several plant sources were nearly as long as that of controls maintained on sucrose solution. In the field, females were highly attracted to 11 of 20 sugar sources, and 8 of these were attractive to males. Peak periods of host attraction for blood-feeding and sugar feeding in open areas were nearly identical and occurred shortly after sunrise and around sunset. In shaded areas, the first sugar-seeking peak occurred between 11:30 and 12:30 while the second was from 16:30 to 17:30. In a 50-day field trial, ATSB significantly reduced mean numbers of landing / biting female Ae. aegypti in the two types of vegetation. At sugar poor sites, the mean pre-treatment catch of 20.51 females on day 14 was reduced 70-fold to 0.29 on day 50. At sugar rich sites, the mean pre-treatment catch of 32.46 females on day 14 was reduced 10-fold to a mean of 3.20 females on day 50.
This is the first study to show how the vector Ae. aegypti depends on environmental resources of sugar for feeding and survival. The demonstration that Ae. aegypti populations rapidly collapsed after ATSB treatment, in both sugar rich and sugar poor environments, is strong evidence that Ae. aegypti is sugar-feeding frequently. Indeed, this study clearly demonstrates that Ae. aegypti mosquitoes depend on natural sugar resources, and a promising new method for vector control, ATSB, can be highly effective in the fight against Aedes-transmitted diseases.
Current management and control of Aedes aegypti populations in urban areas are based on the spraying of insecticides. Here, we evaluated the effectiveness of spraying larvicide (Bacillus ...thuringiensis israelensis) using a truck-mounted Buffalo Turbine and adulticide (Deltamethrin) using a Grizzly ULV Sprayer in an urban area with high densities of Ae. aegypti and many cryptic and difficult to reach aquatic breeding habitats. Experiments were conducted in a tire shop located in Miami-Dade County, Florida with approximately 100,000 used airplane tires. Insecticide interventions were performed after a baseline survey consisting of 3 weeks of collections, followed by two insecticide interventions: (i) application of the adulticide followed by the application of larvicide on the subsequent week; and (ii) application of both adulticide and larvicide on two consecutive weeks. The first insecticide intervention resulted in a non-significant decrease in the relative abundance of Ae. aegypti. On the other hand, the second insecticide intervention significantly reduced the Ae. aegypti relative abundance (P < 0.002). Our results demonstrated that the combined insecticide interventions on two consecutive weeks significantly reduced the relative abundance of Ae. aegypti. This result indicated that the larvicide was successfully propelled reaching cryptical and difficult to reach aquatic habitats. However, even though the number of mosquitoes was greatly reduced, it was still greatly above the 10-mosquito threshold by trap night used by the Miami-Dade Mosquito Control Division to deploy an inspector to survey the area. Considering the lack of new and effective mosquito control tools, efficient and mobile insecticide propellers such as Buffalo Turbine can be of great help to manage mosquito populations in urban areas.
Urbanization processes are increasing globally. Anthropogenic alterations in the environment have profound effects on biodiversity. Decreased biodiversity due to biotic homogenization processes as a ...consequence of urbanization often result in increased levels of mosquito vector species and vector-borne pathogen transmission. Understanding how anthropogenic alterations in the environment will affect the abundance, richness, and composition of vector mosquito species is crucial for the implementation of effective and targeted mosquito control strategies. We hypothesized that anthropogenic alterations in the environment are responsible for increasing the abundance of mosquito species that are adapted to urban environments such as Aedes aegypti and Culex quinquefasciatus. Therefore, our objective was to survey mosquito relative abundance, richness, and community composition in Miami-Dade County, Florida, in areas with different levels of urbanization. We selected 24 areas, 16 remote areas comprised of natural and rural areas, and 8 urban areas comprised of residential and touristic areas in Miami-Dade County, Florida. Mosquitoes were collected weekly in each area for 24 h for 5 consecutive weeks from August to October 2020 using BG-Sentinel traps baited with dry ice. A total of 36,645 mosquitoes were collected, from which 34,048 were collected in the remote areas and 2,597 in the urban areas. Our results show a clear and well-defined pattern of abundance, richness, and community composition according to anthropogenic modifications in land use and land cover. The more urbanized a given area the fewer species were found and those were primary vectors of arboviruses, Ae. aegypti and Cx. quinquefasciatus.
Vector-borne diseases are an increasing issue to public health, endangering billions of people worldwide. Controlling vector mosquitoes is widely accepted as the most effective way to prevent ...vector-borne disease outbreaks. Mosquito surveillance is critical for the development of control strategies under the integrated vector management framework. We hypothesize that the effectiveness and reliability of using BG-Sentinel traps for the surveillance strongly depend on the bait used to attract mosquitoes. The objective of this study was to compare the effectiveness of BG-Sentinel traps baited with CO2 and BG-Lure. A total of 72 traps were deployed for 48 hours once a week for four weeks. For the initial 24-hour period, the traps were baited with CO2, and then for an additional 24 hours using the BG-Lure. Collected mosquitoes were analyzed using the Generalized Estimating Equation for repeated measures analysis. Biodiversity was assessed by the Shannon and Simpson indices and by individual rarefaction curves and SHE profiles. A total of 5,154 mosquitoes were collected, from which 3,514 by traps baited with CO2 and 1,640 mosquitoes by traps baited with BG-Lure. Aedes aegypti and Culex quinquefasciatus were the most abundant and dominant species. Results from the Generalized Estimating Equation models indicated that more than twice as many mosquitoes were attracted CO2 than to the BG-Lure. The comparison of attractiveness of CO2 and BG-Lure to Ae. aegypti and Cx. quinquefasciatus was non-significant, suggesting that both species were equally attracted by the baits. The individual rarefaction curves for Ae. aegypti and Cx. quinquefasciatus imply that traps baited with BG-Lure underestimated mosquito species richness compared to those baited with CO2. BG-Lure were less effective in attracting mosquitoes with low abundances and failed to collect Cx. coronator and Cx. nigripalpus, which were consistently collected by traps baited with CO2. According to our results, CO2 significantly (P<0.05) attracted more mosquitoes (2.67 adjusted odds ratios) than the BG-Lure when adjusted for time and species, being more effective in assessing the relative abundance of vector mosquitoes and yielding more trustworthy results. Traps baited with CO2 collected not only more specimens, but also more species in a more consistent pattern.
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