Insecticide resistance in Culex quinquefasciatus Say, 1823 in Brazil: a review

Abstract

Culex quinquefasciatus is a successful invasive species broadly distributed in subtropical regions, including Brazil. It is an extremely annoying mosquito due to its nocturnal biting behavior, in high-density populations and it is a potential bridge between sylvatic arbovirus from birds to man in urban territories. Herein, we present a review concerning the methods of chemical control employed against Cx. quinquefasciatus in Brazil since the 1950’s and insecticide resistance data registered in the literature. As there is no specific national programme for Cx. quinquefasciatus control in Brazil, the selection of insecticide resistance is likely due in part to the well-designed chemical campaigns against Aedes aegypti and the elevated employment of insecticides by households and private companies. There are very few publications about insecticide resistance in Cx. quinquefasciatus from Brazil when compared to Ae. aegypti. Nevertheless, resistance to organophosphates, carbamate, DDT, pyrethroids and biolarvicides has been registered in Cx. quinquefasciatus populations from distinct localities of the country. Concerning physiological mechanisms selected for resistance, distinct patterns of esterases, as well as mutations in the acetylcholinesterase (ace-1) and voltage-gated sodium channel (NaV) genes, have been identified in natural populations. Given environmental changes and socioeconomical issues in the cities, in recent years we have been experiencing an increase in the number of disease cases caused by arboviruses, which may involve Cx. quinquefasciatus participation as a key vector. It is urgent to better understand the efficiency and susceptibility status to insecticides, as well as the genetic background of known resistant mechanisms already present in Cx. quinquefasciatus populations for an effective and rapid chemical control when eventually required.

Optimized CRISPR tools and site-directed transgenesis towards gene drive development in Culex quinquefasciatus mosquitoes

“…Current insecticide-based mosquito control strategies are beginning to fail due to the development of resistance in Culex populations 15 , 16 . Fortunately, the advent of CRISPR has allowed for the development of alternative genetic–engineering-based strategies that prevent disease transmission or suppress vector populations 17 , 18 .…”

Kdr genotyping in Aedes aegypti from Brazil on a nation-wide scale from 2017 to 2018

“…However, pyrethroid resistance was also confirmed a few years later 8 . Currently, the organophosphate malathion is employed by governmental campaigns in the entire country as the only alternative to pyrethoids, although the latter class of compounds is still intensively used in households and by private companies for mosquito control, as well as against other urban insect vectors, such as Culex , sandflies, anophelines and triatomines 6 , 9 , 10 .…”

Misuse, perceived risk, and safety issues of household insecticides: Qualitative findings from focus groups in Arequipa, Peru

“…Research in the Argentine Chaco indicated that households with domestic insecticide use were less likely to be infested with triatomines prior to the initiation of a formal spray campaign, indicating that household insecticide use plays an important role in vector control [ 15 ]. However, there is also evidence that the use of household insecticides contributes to health impacts for family members and insecticide resistance [ 17 , 32 , 33 ]. Of the major household brands identified in the current study many include pyrethroid insecticides, a class that is widely used in the Americas for control of Chagas disease [ 31 ] and presents a risk for development of resistance as well as acute health impacts [ 31 , 34 , 35 ].…”