930 © The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. Vector Control, Pest Management, Resistance, Repellents Fitness Cost of Sequential Selection with Deltamethrin in Aedes aegypti (Diptera: Culicidae) Francisco J. Gonzalez-Santillan, 1 Yamili Contreras-Perera, 2 Jesus A. Davila-Barboza, 1 Alan E. Juache-Villagrana, 1 Selene M. Gutierrez-Rodriguez, 1 Gustavo Ponce-Garcia, 1 Beatriz Lopez-Monroy, 1 Iram P. Rodriguez-Sanchez, 1, Audrey E. Lenhart, 3 Lucy Mackenzie-Impoinvil, 3 and Adriana E. Flores 1,4, 1 Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Biologicas, Avenida Universidad s/n Ciudad Universitaria, San Nicolas de los Garza, NL 66455, Mexico, 2 Universidad Autonoma de Yucatan, UCBE-UADY, Merida, Yucatan, Mexico, 3 Entomology Branch, Division of Parasitic Disease and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, USA, and 4 Corresponding author, e-mail: adriana.foressr@uanl.edu.mx Disclaimer: The fndings and conclusions in this paper are those of the authors and do not necessarily represent the offcial position of the Centers for Disease Control and Prevention. Subject Editor: Donald Yee Received 5 November 2021; Editorial decision 22 February 2022. Abstract In Mexico, Aedes aegypti (L.) is the primary dengue vector, chikungunya, and Zika viruses. The continued use of synthetic pyrethroids has led to the development of resistance in target populations, which has diminished the effectiveness of vector control programs. Resistance has been associated with disadvantages that affect the biological parameters of resistant mosquitoes compared to susceptible ones. In the present study, the dis- advantages were evaluated by parameters related to survival and reproduction (‘fitness cost’) after selection with deltamethrin for five generations. The parameters analyzed were the length of the development cycle, sex ratio, survival, longevity, fecundity, egg viability, preoviposition, oviposition and postoviposition periods, and growth parameters. In the deltamethrin-selected strain, there was a decrease in the development cycle dur- ation, the percentage of pupae, the oviposition period, and eggs viability. Although mean daily fecundity was not affected after the selection process, this, together with the decrease in the survival and fecundity levels by specific age, significantly affected the gross reproductive rate (G RR ), net reproductive rate (R o ), and intrinsic growth rate (r m ) of the group selected for five generations with deltamethrin compared to the group without selection. Identifying the ‘cost’ of resistance in biological fitness represents an advantage if it is desired to limit the spread of resistant populations since the fitness cost is the less likely that resistant individuals will spread in the population. This represents an important factor to consider in designing integrated vector management programs. Key words: ftness cost, deltamethrin, sequential selection Aedes aegypti is a species that displays anthropophilic behavior linked to humans, carrying out its life cycle mainly in artifcial larval habitats, colonizing objects produced by humans that accumulate water, which are found around the home. This mosquito is one of the main vectors of dengue, chikungunya, Zika, and yellow fever viruses and represents a public health problem that is increasing since around two-thirds of the world’s population live in areas infested by Ae. aegypti. In Mexico, Ae. aegypti is distributed in at least 29 of the 32 states of the republic (Zapata-Peniche et al. 2007, Imam et al. 2014). Since the 1950s, vector control programs in Mexico have used multiple classes of chemical in- secticides, but since 1999, these programs have relied heavily on syn- thetic pyrethroids for adult vector control (DOF 2003, CENAPRECE 2021). However, their effcacy has been affected by increased resistance in target populations, a phenomenon that occurs worldwide and spreads rapidly due to the continuous pressure with the insecticides (Nkya et al. 2013, Saavedra-Rodriguez et al. 2015). Journal of Medical Entomology, 59(3), 2022, 930–939 https://doi.org/10.1093/jme/tjac032 Advance Access Publication Date: 7 April 2022 Research Downloaded from https://academic.oup.com/jme/article/59/3/930/6564619 by guest on 05 August 2023