Chapters authored
Insecticide-Treated House Screens to Reduce Infestations of Dengue Vectors
The public health importance of the endophilic mosquito Aedes aegypti increased dramatically in the recent decade, because it is the vector of dengue, chikungunya, Zika and yellow fever. The use of long-lasting insecticidal nets (LLINs) fixed on doors and windows, as insecticide-treated screening (ITS), is one innovative approach recently evaluated for Aedes control in South Mexico. From 2009 to 2014, cluster-randomised controlled trials were conducted in Acapulco and Merida. Intervention clusters received Aedes-proof houses (‘Casas a prueba de Aedes’) with ITS and were followed up during 2 years. Overall, results showed significant and sustained reductions on indoor adult vector densities in the treated clusters with ITS after 2 years: ca. 50% on the presence (OR ≤ 0.62, P < 0.05) and abundance (IRR ≤ 0.58, P < 0.05). ITS on doors and windows are ‘user-friendly’ tool, with high levels of acceptance, requiring little additional work or behavioural change by householders. Factors that favoured these interventions were (a) house construction, (b) high coverage achieved due to the excellent acceptance by the community and (c) collaboration of the vector control services; and only some operational complaints relating to screen fragility and the installation process. ITS is a housing improvement that should be part of the current paradigms for urban vector-borne disease control.
Part of the book: Dengue
Mosquito Excito-Repellency: Effects on Behavior and the Development of Insecticide Resistance
Mosquito’s resistance to avoiding insecticide-treated surfaces (“excito-repellency”) has two effects: irritation from direct contact with a treated area and repellency as an avoidance response to contact with treated surfaces. Nowadays, this behavior appears to reduce the success of mosquito control programs, particularly those based on insecticide-driven strategies. Different systems have been designed to assess the excito-repellency, evaluating numerous insecticides’ irritants, deterrents, and toxic properties at different concentrations. The information provides valuable insights regarding the patterns of mosquito behavior based on their physiological conditions, such as the age of the mosquitoes and the duration of the tests. However, the physiological processes resulting from chemical stimulus contact “chemoreception”) are still poorly explored and understood. This review provides an overview of insecticide effects on mosquito behavior and describes the mechanisms involved in chemical stimuli uptake, translation, and recognition.
Part of the book: Mosquito Research
Community Engagement and Social Assessment for Wolbachia-Based Suppression of Natural Populations of Aedes aegypti: The Mexican Experience
The Wolbachia-based approach is under evaluation as a control strategy against Aedes aegypti in Mexico. From 2017 to 2019, we performed a pilot study to evaluate an open-field mass-release of wAlbB-infected Ae. aegypti male mosquitoes, as part of an integrated vector management (IVM) plan led by the Ministry of Health in Mexico to suppress natural populations of Ae. aegypti in southern Mexico. Community engagement and social evaluation were part of the key activities conducted. Overall, results showed the positive benefits of this Wolbachia-based method in the reduction of Aedes mosquitoes (90%). Mosquito’s nuisance at bedtime and the increasing circulation of mosquitoes during the releasing days were reported as the negative perceptions of this method. Importantly, participants understood the difference between wild mosquitoes and those released as part of the project, as well as the importance of the IVM. A significant number of the population accepted and supported the project, and feedback was given to improve future mosquito-releasing activities. The social license was a key factor in the success of the intervention and should be part of innovative paradigms for mosquito-vector control strategies involving community engagement. We outline the Mexican experience of community engagement and social assessment in implementing a Wolbachia-based strategy.
Part of the book: Mosquito Research
Low-Cost Materials for Do-It-Yourself (DIY) Installation of House Screening against Aedes aegypti
House-screening (HS) using fixed-aluminium frames to reduce the risk of indoor infestation with Aedes aegypti mosquitoes as well as the risk of Aedes-transmitted diseases in communities living in endemic areas. However, the success of this approach has been hindered by the elevated cost of the aluminium-based materials as well as their professional installation, which cannot be afforded by people living under vulnerable conditions. Cost-saving strategies such as the use of low-cost materials including wood, PVC, and Velcro are within the list of HS options available and offered by HS businesses and/or Do-it-yourself (DIY) packages verbi gratia ready-made and ready-to-install mosquito-screens. Here, we evaluated the efficacy of low-cost frames constructed with different materials to protect against Ae. aegypti indoor infestation using experimental huts. The efficacy of protection in preventing female mosquito passing inside the huts of any of the options of frames was high (>93%) compared to the control with no-screen. People’s perceptions on the different materials showed the most “popular” alternative was the frame made of wood (62%). All the prototype-frames of HS made of different materials were effective at blocking Ae. aegypti entering-mosquitoes particularly, low-cost options like magnets and Velcro.
Part of the book: Mosquito Research