Considerations on strategies for the control of Aedes aegypti
Technical note of edition 10 on considerations on strategies for the control of Aedes aegypti, with a focus on diagnosis, prevention and criteria applicable to professional pest management.
The fight against mosquitoes is ancient and complex, proof of this is that they are considered to date the most lethal predators of man. In 1909, Dr. Rubert Boyce, founder of the Liverpool School of Tropical Medicine, noted that the fate of human civilization would be decided by a simple question: Mosquito or man? Most researchers think that specializing in people would have had no particular advantage for mosquitoes before the development of sedentary cultures about 10,000 years ago.
However, sedentary lifestyle and the need to store water conditioned the reproductive dependence of mosquitoes, particularly in arid regions. Aedes aegypti can be considered one of the most important mosquitoes for public health, given its high degree of anthropophily, resistance to egg desiccation, oviposition in multiple reservoirs by gonotrophic cycle, wide geographical distribution, adaptability to urban centers and vector capacity. However, dengue outbreaks have also been attributed to Aedes albopictus, Aedes polynesiensis and several species of the Aedes scutellaris complex.
Each of these species with its own ecology, behavior and geographical distribution. A study carried out at Princeton University with Aedes aegypti obtained from 27 locations in sub-Saharan Africa to measure food preference between humans and guinea pigs, found that mosquitoes from highly populated areas were more attracted to human odors. The most revealing result being that linked to climate, mosquitoes that came from places that had a rainy season followed by a long, hot dry season, preferred humans. This may be related to the theory that mosquitoes evolved closer to humans due to our unique ability to store water during dry seasons. It is still worrying that several scientific articles warn about the expansion of its distribution area considering, among other factors, the growth of the city, climate change and global warming, which is why it is urgent to validate alternative and complementary strategies for its control. Regarding vector surveillance activities, it is necessary to improve existing entomological indicators and develop new indicators that better reflect the
transmission potential with greater predictive power. Regarding control, the integration of various tools is urgently needed to obtain synergistic benefits, including the attack on immature and adult stages. A recurring concern is the increasingly growing resistance of mosquito populations to insecticides with various modes of action. In this context, currently, applications of larvicides, immediate-effect adulticides, residual-effect adulticides, IGRs such as methoprene and pyriproxyfen including increased self-dissemination by males, biolarvicides such as BTI, monomolecular films, lethal traps, the sterile mosquito technique from which sterile male insects are released to increase the chances that they outnumber males are being used. fertile, so that when mating with fertile females, they make their offspring not viable, as well as the use of the Wolbachia bacteria that reduces the ability of Aedes aegypti mosquitoes to become infected with the dengue, Zika and chikungunya viruses.
Also on a smaller scale, arthropods and larvivorous fish, entomopathogenic fungi, specific parasites are used, and the use of toxic sugar bait is reported. Regarding new larvicides, the use of SPINOSAD stands out, a product derived from a natural soil bacteria Saccharopolyspora spinosa, whose active compound is a neurotoxin formed by a mixture of spinosins A and D, being the first health larvicide.
public in the chemical classification IRAC Class 5: Allosteric modulators of the nicotinic acetylcholine receptor – site I. It has WHOPES approval for use in domestic water and is formulated as liquid, granules or tablets, being very easy to apply unlike other larvicides. Studies carried out in southern Mexico, the USA, Peru, Brazil, Panama, Colombia and other places demonstrate the effectiveness of the product for more than three months in the control of Aedes aegypti. Thus, a study developed by the GORGAS MEMORIAL INSTITUTE OF HEALTH STUDIES “Evaluation of the bioefficacy of the larvicidal agent Natular™ DT in Aedes aegypti Diptera: Culicidae) under field conditions” records after 90 days of exposure of Aedes aegypti larvae to the insecticide Natular DT an average mortality percentage of 98.5%, with a median equal to 98.5%. Faced with the increase in
resistance of the mosquito in question to different types of insecticides in the region of the Americas, this product showed high bioefficacy and was able to maintain a high toxic residuality against larvae for a period of three months. In general terms, it is necessary to improve resources and skills for vector control, as well as develop basic and applied research, promoting innovation to adapt successful strategies locally. The political commitment expressed in public health guidelines and its budgetary correlation, as well as community participation, are no less important. Likewise, the design of inter-programmatic strategies and intersectoral actions, including education, housing improvement and basic sanitation, are necessary to modify the social and environmental determinants of vector-borne diseases.
Aedes aegypti CAN BE CONSIDERED ONE OF THE MOSQUITOES OF GREATEST IMPORTANCE FOR PUBLIC HEALTH, BASED ON ITS HIGH DEGREE OF ANTHROPOPHILY, RESISTANCE TO EGGS DESSICATION, OVIPOSITION IN MULTIPLE RESERVOIRS BY GONOTROPHIC CYCLE, WIDE GEOGRAPHICAL DISTRIBUTION, ADAPTABILITY TO URBAN CENTERS AND VECTOR CAPACITY.