Identification of a major Quantitative Trait Locus determining resistance to the organophosphate temephos in the dengue vector mosquito Aedes aegypti

Abstract

Organophosphate insecticides (OP) have extensively been used to control mosquitoes, such as the vector Aedes aegypti. Unfortunately, OP resistance has hampered control programs worldwide. We used Quantitative Trait Locus (QTL) mapping to evaluate temephos resistance in two F1 intercross populations derived from crosses between a resistant Ae. aegypti strain (RecR) and two susceptible strains (MoyoD and Red). A single major effect QTL was identified on chromosome 2 of both segregating populations, named rtt1 (resistance to temephos 1). Bioinformatics analyses identified a cluster of carboxylesterase genes (CCE) within the rtt1 interval. qRT-PCR demonstrated that different CCEs were up-regulated in F2 resistant individuals from both crosses. However, none exceeded the 2-fold expression. Primary mechanisms for temephos resistance may vary between Ae. aegypti populations, yet also appear to support previous findings suggesting that multiple linked esterase genes may contribute to temephos resistance in the RecR strain as well as other populations.

Insecticide resistance in mosquitoes: Development, mechanisms and monitoring

“…Other advance molecular based methods such as microsatellite genotyping to identify level of carboxylesterases in Ae. aegypti have improved the efficiency of monitoring resistance mechanisms (Paiva et al,, 2016). Detoxification chips have been introduced to estimate differential expression of metabolic enzyme genes using microarray analysis of cDNA (David et al, 2005;Strode et al, 2008).…”

A cluster of CYP6 gene family associated with the major quantitative trait locus is responsible for the pyrethroid resistance in Culex pipiens pallen

“…() confirmed that mutations in the para voltage‐gated sodium channel gene are responsible for permethrin resistance by the major QTL, which cause target‐site insensitivity; and Paiva et al . () identified a cluster of carboxylesterase genes (CCE) determining resistance to the organophosphate temephos within the major QTL interval. In Culex , previous studies mainly focused on the association between one or a few genes and pyrethroids resistance (Li et al ., ; Fang et al ., ; Lv et al ., ; Gong et al ., ).…”

Multiple insecticide resistance mechanisms in primary dengue vector, Aedes aegypti (Linn.) from dengue endemic districts of sub-Himalayan West Bengal, India

“…Mainly, the insecticide detoxification enzyme groups associated with resistance against temephos are CCEs [ 33 – 34 ], however some studies also suggest the role of other detoxifying enzymes such as CYP 450 s and GSTs [ 35 ]. The use of synergist TPP but not PBO was found to restore the susceptibility to temephos in NDP population, thus pinpointing the mechanism of temephos resistance in this population to be CCE mediated metabolic detoxification.…”

“…Involvement of CCEs in development of resistance against temephos have also been noted in many populations of Ae . aegypti throughout the world [ 33 – 34 , 36 ].…”