Development of contact insecticide and application device - effectiveness proof on Aedes aegypti larvae

Abstract

The mosquito Aedes aegypti is the main transmitter of dengue, chikungunya, zika and urban yellow fever. Among these endemics, only yellow fever currently has immunological control applied in large scale. Vaccines for dengue and zika viruses currently under development may still require 2 or 3 years until they become distributed by the public system. Therefore, the vector control is the only alternative meanwhile to prevent the worsening of the epidemiological crisis resulting from these endemics.In the larval control of A. Aegypti, actives with low toxicological risk for people and environment have been applied, mainly those, to be used in drinking water reservoirs. In addition to these factors, the larvicide persistence is an important issue as well. However, compliance with these requirements by some kinds of larvicides could be considered precarious. As an example, we can cite the biolarvicide Bacillus thuringiensis and the larvicides based on the active pyriproxyfen. The biolarvicide based on the bacteria Bacillus thuringiensis although considered safe, presents a variable range of persistence. Depending on the strain and its direct exposure to the sun ray, its persistence may ranges from 1 to 11 weeks - less than 120 days required. In the case of larvicides based on pyriproxyfen, it was verified that, accumulation spots of this active in the environment could take place. These accumulations interfere negatively on surrounding populations of non-target species, leading to their elimination as have been verified with bee population.In order to evaluate an alternative to this problem, we propose the development of insecticidal technology based on formulations of natural and derivates actives showing insecticidal characteristics, low toxicological risk to people and environmentally friendship. Its action is based on the formation of a thin layer that replaces the original air-water interface in perennial breeding sites, changing its physico-chemical characteristics. The mortality of the target insect stems are due to environmental changes which worsening its survival conditions and usually leads dead by hypoxia. The proposed larvicidal technology comprises two components:1) Net formulation of biodegradable assets with low potential for collateral risk in humans, animals or the environment, and2) Dispensing device with flow restrictor element for the continuous and controlled release of microdosages of the solution in water reservoirs. In this way, it is possible to obtain effective preventive vector control for adjustable periods of persistence. (AU)