Susceptibility to insecticides and resistance mechanisms in three populations of Aedes aegypti from Peru

Abstract

BackgroundEpidemics of dengue, chikungunya and Zika are a growing threat to areas where Aedes aegypti are present. The efficacy of chemical control of Ae. aegypti is threatened by the increasing frequency of insecticide resistance. The objective of this study was to determine the susceptibility status as well as the biochemical and molecular mechanisms underlying insecticide resistance in three populations of Ae. aegypti in high risk areas of dengue, chikungunya, and Zika in Peru.MethodsBioassays were conducted on adult Ae. aegypti to evaluate their susceptibility to insecticides used currently or historically for mosquito control in Peru, including six pyrethroids, three organophosphates and one organochlorine, in populations of Ae. aegypti from the districts of Chosica (Department of Lima), Punchana (Department of Loreto) and Piura (Department of Piura). Resistance mechanisms were determined by biochemical assays to assess activity levels of key detoxification enzyme groups (nonspecific esterases, multi-function oxidases, glutathione S-transferases and insensitive acetylcholinesterase). Real-time PCR assays were used to detect two kdr mutations (V1016I and F1534C) on the voltage-gated sodium channel gene.ResultsResistance to DDT was detected in all three populations, and resistance to pyrethroids was detected in all populations except the population from Chosica, which still exhibited susceptibility to deltamethrin. Resistance to organophosphates was also detected, with the exception of populations from Punchana and Piura, which still demonstrated susceptibility to malathion. In general, no increase or alteration of activity of any enzyme group was detected. Both 1016I and 1534C alleles were detected in Punchana and Piura, while only the 1534C allele was detected in Chosica.ConclusionsThe results suggest that resistance to multiple classes of insecticides exist in areas important to Ae. aegypti-borne disease transmission in Peru. The F1534C mutation was present in all 3 populations and the V1016I mutation was present in 2 populations. To our knowledge, this is the first report of the presence of 1016I and 1534C in Ae. aegypti in Peru. The absence of highly elevated enzymatic activity suggests that target site resistance is a key mechanism underlying insecticide resistance in these populations, although further research is needed to fully understand the role of metabolic resistance mechanisms in these populations.

Habitat characteristics and insecticide susceptibility of Aedes aegypti in the Ifakara area, south-eastern Tanzania

“…Since this study was the first of its kind in this geographical area, there were no immediate comparisons for the resistance profiles. However, in studies carried out in Dar es Salaam, Peru and Burkina Faso, resistance to pyrethroids and organophosphate was obvious [20,50,51]. Reduced susceptibility to pyrethroids observed in some of assays, and the resistance seen against bendiocarb in the rainy season are however signs that we must remain vigilant as insecticide resistance could rapidly spread among the vector populations once active control programmes begin.…”

“…In each experiment 120-150 mosquitoes were used, so that there were 20-25 individuals per test. Untreated controls were included, and the mosquitoes were initially observed for 60 minutes to observe knockdown at 10,15,20,30,40,50 and 60 min. The exposed and non-exposed mosquitoes were then provided with 10% glucose and maintained at 28.0 ± 1.0 °C and 80 ± 10% relative humidity, then overall mortality observed after 24 hours.…”

Combination ofkdrmutation and detoxification gene expression associated with high tolerance for permethrin in a resistantAedes aegyptipopulation

“…aegypti . However, involvement of GST proteins in resistance still needs to be assessed although assignment of an actual role of GST in permethrin resistance might not be straightforward [58,59]. It is critical to investigate permethrin-specific detoxification genes in mosquito populations with variable resistance ratios, such as in the Florida mosquito populations used in this study, so that their actual role in permethrin detoxification can be assessed and possible resistance countermeasures implemented.…”

Double BR-OVT: a new trap model for collecting eggs and adult mosquitoes from Culex quinquefasciatus and Aedes spp.

“…The application of chemical insecticides remains as the main method used to control mosquitoes 12,13 . However, the continuous use of these products causes a selective pressure, leading to the emergence of mosquitoes resistant to these compounds, that also have harmful effects on humans, other animals, and to the environment, requiring periodic assessment of their continued use.…”

“…However, the continuous use of these products causes a selective pressure, leading to the emergence of mosquitoes resistant to these compounds, that also have harmful effects on humans, other animals, and to the environment, requiring periodic assessment of their continued use. In addition, the use of chemical pesticides requires the monitoring of the susceptibility of the mosquito population exposed to them, which results in the replacement of the product used in the mosquito control strategy 13,14 . In this sense, the use of more sustainable tools and strategies, such as an integrated vector control (IVC) strategy, has been gaining evidence [15][16][17] .…”