Optimization of the Aedes aegypti Control Strategies for Integrated Vector Management

We formulate an infinite-time quadratic functional minimization problem of Aedes aegypti mosquito population. Three techniques of mosquito population management, chemical insecticide control, sterile insect technique control, and environmental carrying capacity reduction, are combined in order to obtain the most sustainable strategy to reduce mosquito population and consequently dengue disease. The solution of the optimization control problem is based on the ideas of the Dynamic Programming and Lyapunov Stability using State-Dependent Riccati Equation (SDRE) control method. Different scenarios are analyzed combining three mentioned population management efforts in order to assess the most sustainable policy to reduce the mosquito population

A Systematic Review of Mosquito Coils and Passive Emanators: Defining Recommendations for Spatial Repellency Testing Methodologies.

Mosquito coils, vaporizer mats and emanators confer protection against mosquito bites through the spatial action of emanated vapor or airborne pyrethroid particles. These products dominate the pest control market; therefore, it is vital to characterize mosquito responses elicited by the chemical actives and their potential for disease prevention. The aim of this review was to determine effects of mosquito coils and emanators on mosquito responses that reduce human-vector contact and to propose scientific consensus on terminologies and methodologies used for evaluation of product formats that could contain spatial chemical actives, including indoor residual spraying (IRS), long lasting insecticide treated nets (LLINs) and insecticide treated materials (ITMs). PubMed, (National Centre for Biotechnology Information (NCBI), U.S. National Library of Medicine, NIH), MEDLINE, LILAC, Cochrane library, IBECS and Armed Forces Pest Management Board Literature Retrieval System search engines were used to identify studies of pyrethroid based coils and emanators with key-words "Mosquito coils" "Mosquito emanators" and "Spatial repellents". It was concluded that there is need to improve statistical reporting of studies, and reach consensus in the methodologies and terminologies used through standardized testing guidelines. Despite differing evaluation methodologies, data showed that coils and emanators induce mortality, deterrence, repellency as well as reduce the ability of mosquitoes to feed on humans. Available data on efficacy outdoors, dose-response relationships and effective distance of coils and emanators is inadequate for developing a target product profile (TPP), which will be required for such chemicals before optimized implementation can occur for maximum benefits in disease control

Sterile Insect Technique in an Integrated Vector Management Program against Tiger Mosquito Aedes albopictus in the Valencia Region (Spain): Operating Procedures and Quality Control Parameters

The Asian tiger mosquito Aedes albopictus (Skuse, 1894) is an invasive species responsible for the transmission of arboviruses such as dengue, Zika and chikungunya. The rapid expansion of this species globally is the result of a lack of effective control methods. In this context, the sterile insect technique (SIT) is an emerging tool for controlling mosquito populations. The Agriculture Department of the Valencian Region (Spain) is promoting a pilot project to evaluate the efficacy of the sterile insect technique as part of an integrated vector management program against Ae. albopictus. From 2018 to 2020, sterile male releases were carried out in two pilot sites, releasing more than 15 million sterile males over 80 ha. The present work describes the laboratory studies carried out to evaluate the performance of irradiated males to assess the feasibility of the SIT before release in the field, as well as the production and quality control parameters obtained in rearing activities. The obtained values in terms of production and quality control and the proposed rearing methodology can be useful for designing a medium-scale mosquito-rearing pipeline.Ciencias Experimentale

Scientific achievements and reflections after 20 years of vector biology and control research at the Pu Teuy mosquito field research station, Thailand

Additional vector control tools are needed to supplement current strategies to achieve malaria elimination and control of Aedes-borne diseases in many settings in Thailand and the Greater Mekong Sub-region. Within the next decade, the vector control community, Kasetsart University (KU), and the Ministry of Higher Education, Science, Research and Innovation must take full advantage of these tools that combine different active ingredients with different modes of action. Pu Teuy Mosquito Field Research Station (MFRS), Department of Entomology, Faculty of Agriculture, Kasetsart University (KU), Thailand was established in 2001 and has grown into a leading facility for performing high-quality vector biology and control studies and evaluation of public health insecticides that are operationally relevant. Several onsite mosquito research platforms have been established including experimental huts, a 40-m long semi-field screening enclosure, mosquito insectary, field-laboratory, and living quarters for students and researchers. Field research and assessments ranged from ‘basic’ investigations on mosquito biology, taxonomy and genetics to more ‘applied’ studies on responses of mosquitoes to insecticides including repellency, behavioural avoidance and toxicity. In the course of two decades, 51 peer-reviewed articles have been published, and 7 masters and 16 doctoral degrees in Entomology have been awarded to national and international students. Continued support of key national stakeholders will sustain MFRS as a Greater Mekong Subregion centre of excellence and a resource for both insecticide trials and entomological research

Development and evaluation of a novel contamination device that targets multiple life-stages of Aedes aegypti.

BACKGROUND: The increasing global threat of Dengue demands new and easily applicable vector control methods. Ovitraps provide a low-tech and inexpensive means to combat Dengue vectors. Here we describe the development and optimization process of a novel contamination device that targets multiple life-stages of the Aedes aegypti mosquito. Special focus is directed to the diverse array of control agents deployed in this trap, covering adulticidal, larvicidal and autodissemination impacts. METHODS: Different trap prototypes and their parts are described, including a floater to contaminate alighting gravid mosquitoes. The attractiveness of the trap, different odor lures and floater design were studied using fluorescent powder adhering to mosquito legs and via choice tests. We demonstrate the mosquitocidal impacts of the control agents: a combination of the larvicide pyriproxyfen and the adulticidal fungus Beauveria bassiana. The impact of pyriproxyfen was determined in free-flight dissemination experiments. The effect on larval development inside the trap and in surrounding breeding sites was measured, as well as survival impacts on recaptured adults. RESULTS: The developmental process resulted in a design that consists of a black 3 Liter water-filled container with a ring-shaped floater supporting vertically placed gauze dusted with the control agents. On average, 90% of the mosquitoes in the fluorescence experiments made contact with the gauze on the floater. Studies on attractants indicated that a yeast-containing tablet was the most attractive odor lure. Furthermore, the fungus Beauveria bassiana was able to significantly increase mortality of the free-flying adults compared to controls. Dissemination of pyriproxyfen led to >90% larval mortality in alternative breeding sites and 100% larval mortality in the trap itself, against a control mortality of around 5%. CONCLUSION: This ovitrap is a promising new tool in the battle against Dengue. It has proven to be attractive to Aedes aegypti mosquitoes and effective in contaminating these with Beauveria bassiana. Furthermore, we show that the larvicide pyriproxyfen is successfully disseminated to breeding sites close to the trap. Its low production and operating costs enable large scale deployment in Dengue-affected locations

The Evolution of Entomological Research with Focus on Emerging and Re-emerging Mosquito-Borne Infections in the Philippines

This paper presented previous and current research efforts for medically important mosquitoes that serve as vectors of emerging and re-emerging diseases in the Philippines, in light of identifying the research gap that exists in the field of public health entomology in the country. This extensive review of the past and current research studies with regard to medical entomology and vector control also attempted to provide proper direction and insights for effective implementation of the country’s vector control programs. All research studies conducted in the Philippines from 1958 up to the present that are related to the paper’s interest and are available on Philippines’ Department of Science and Technology and RITM databases were tracked. Results from this analysis imply that studies on public health entomology in the Philippines have evolved and have gone through various stages of development over time. However, the magnitude of research on medically important mosquitoes in the country is still insufficient for it to contribute comprehensively to integrated methods of vector management and totally eliminate mosquito-borne infections in the Philippines. It is recommended for researchers to work on the continuity of vector researches and explore further the diversity of the entomological aspects of the control of vector-borne diseases

A System Dynamic Transmission Model (SYStrans) to Simulate Epidemic Dengue Environment

Dengue is the most significant arthropod-borne virus in terms of human morbidity and mortality. Geographic expansion of dengue and intensity of outbreak has amplified significantly during the last few decades. Thus, the understanding of the dynamic of the large outbreaks has become indispensable for planning of control interventions in future epidemics. In this regard, local entomological, meteorological and epidemiological parameters based dengue models can be an essential tool for better interpretation of dengue-climate relationship at a regional scale. Process based modelling is resourceful in combining the vector and host dynamic along with the response to the meteorological factors for dengue transmission. In previous studies, process based models have not dealt with the integrated impact of vector-host dynamic and dengue transmission epidemiology by incorporating weather dependent transmission mechanism. In this study, a process-based model has been developed and validated for Iquitos of Peru, based on both vector and host population dynamic as well as the whole infection transmission mechanism. The sole objective was to develop a simple model to represent the actual scenario triggering dengue epidemic considering the most important features of vector population dynamics, transmission mechanism and environmental linkages. The model has used remote sensing or satellite based environmental data and also introduced dew point temperature as a new and effective weather parameter to depict the transmission process of dengue. The model has been capable of simulating the peak and moderate scenario in temporal scale, with considerable quantification of the actual number of cases for the 2004 and 2008 epidemics. Eventually, this type of model can be modified to use for different regions to predict the peak scenario based on local weather parameters effecting the infection transmission and vector development process along with population density