The Impact of Rearing Temperature and Water pH on Longevity and Pesticide Resistance in Aedes Aegypti (Diptera: Culicidae)

Abstract

Aedes aegypti is the most important vector of arboviral disease worldwide. In South-America, this mosquito species is currently responsible for the transmission of dengue fever, yellow fever, chikungunya and Zika. In Ecuador, dengue fever has historically been one of the most important challenges to the public health sector. More recently, the introductions of chikungunya and Zika viruses were followed by periods of intense disease transmission, causing an important burden to the country´s public health infrastructure and economy. Because A. aegypti is an ectotherm and breeds in fresh water pools, environmental conditions can have deep influences on this species´ biology, distribution, population dynamics and vector capacity. To better understand the potential impact of future climate change on A. aegypti´s biology, we studied the effect of variations in environmental temperature and the pH of breeding water on this species´ longevity and pesticide resistance.

Mosquitoes of experimental (geographic) and control strains were reared under different environmental conditions (environmental temperatures of 25°, 28°, 31°C, maintained throughout the insects´ life span;  water pH values of 4, 5 and 6, set at the beginning of larval development). Upon adult emergence, we monitored the longevity and resistance to deltamethrin for each treatment. 

Our results suggest that both environmental temperature and water pH seem to influence adult longevity and pesticide resistance in A. aegypti. Longevity is significantly diminished in temperatures above or below 28°C, as well as with the acidification of the initial breeding water. Similarly, deltamethrin resistance seems to decrease significantly in specimens reared above or below 28^oC, and in specimens reared in more acidic environments.

Although the definitive effects of climate change on A. aegypti biology and physiology in the field are hard to predict, our study contributes novel information about the biology and physiology of this vector species under controlled conditions. This information could help us better predict and understand the effects of putative future climate scenarios on the landscape of arboviral disease transmission.

About the Speaker

After completing his B.Sc. in Biological Sciences at the Pontificia Universidad Católica del Ecuador (PUCE, by its Spanish acronym), Marco joined Ohio University as a graduate student in 1999, where he obtained both a Master´s degree in International Affairs and a Ph.D. degree in Biological Sciences, working under the supervision of Drs. William S. Romoser and Calvin James. Following the completion of his doctoral degree, Marco held postdoctoral posts at the University of Florida (2005-2009) and the Liverpool School of Tropical Medicine (2009-2010), after which he joined British biotech company Oxitec Ltd. as a Senior Scientist (2010-2013). In 2013, Marco joined PUCE as an Associate Professor and Principal Investigator at the Center for Research on Health in Latin America (CISeAL, by its Spanish acronym). Marco was admitted as a member of the Ecuadorian Academy of Sciences in 2014, and he obtained full professorship at PUCE in 2018.

Marco´s work has focused on the biology of medically important mosquito species, covering aspects such as virus/vector interaction, the molecular physiology of larval mosquitoes and the use of genetic engineering as a tool for mosquito control. Currently, Marco´s research focuses on the development of alternative vector control methods, monitoring pesticide resistance in field mosquito populations and understanding the effects of climate change in mosquito biology. Additionally, he teaches several graduate and undergraduate courses at PUCE´s School of Biology and Medical School.

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