‘What I cannot create, I do not understand’: functionally validated synergism of metabolic and target site insecticide resistance

Abstract

The putative synergistic action of target-site mutations and enhanced detoxification in pyrethroid resistance in insects has been hypothesized as a major evolutionary mechanism responsible for dramatic consequences in malaria incidence and crop production. Combining genetic transformation and CRISPR/Cas9 genome modification, we generated transgenic Drosophila lines expressing pyrethroid metabolizing P450 enzymes in a genetic background along with engineered mutations in the voltage-gated sodium channel ( para ) known to confer target-site resistance. Genotypes expressing the yellow fever mosquito Aedes aegypti Cyp9J28 while also bearing the para V1016G mutation displayed substantially greater resistance ratio (RR) against deltamethrin than the product of each individual mechanism (RR combined : 19.85 > RR Cyp9J28 : 1.77 × RR V1016G : 3.00). Genotypes expressing Brassicogethes aeneus pollen beetle Cyp6BQ23 and also bearing the para L1014F ( kdr ) mutation, displayed an almost multiplicative RR (RR combined : 75.19 ≥ RR Cyp6BQ23 : 5.74 × RR L1014F : 12.74). Reduced pyrethroid affinity at the target site, delaying saturation while simultaneously extending the duration of P450-driven detoxification, is proposed as a possible underlying mechanism. Combinations of target site and P450 resistance loci might be unfavourable in field populations in the absence of insecticide selection, as they exert some fitness disadvantage in development time and fecundity. These are major considerations from the insecticide resistance management viewpoint in both public health and agriculture.

Untangling a Gordian knot: the role of a GluCl3 I321T mutation in abamectin resistance in Tetranychus urticae

“…We confirm the antagonistic effect of abamectin on all three Rdls, suggesting that abamectin also acts on Rdls at high doses in T. urticae . We therefore propose that the I321T GluCl3 mutation plays a role in abamectin resistance, but only in combination with synergistic additional factors that deserve more investigation 75 …”

“…We therefore propose that the I321T GluCl3 mutation plays a role in abamectin resistance, but only in combination with synergistic additional factors that deserve more investigation. 75…”

Permethrin Resistance in Aedes aegypti Affects Aspects of Vectorial Capacity

“…Homozygous kdr mutations at both nucleotides 1016 and 1534 of the voltage-gated sodium channel gene were characterized in the p-s population and might contribute to high resistance to permethrin. In fact, co-occurrence of multiple resistance mechanisms, such as the V1016G kdr mutation and overexpression of CYP9J28 , was shown to be synergistic in conferring pyrethroid resistance in genetically engineered Drosophila [ 62 ]. We noticed the p-s population had a longer survival time in the adult stage, moreover, the dissemination rate of DENV-1 in the p-s population was significantly higher than its parental population, Key West.…”

Co-Expression of a Homologous Cytochrome P450 Reductase Is Required for In Vivo Validation of the Tetranychus urticae CYP392A16-Based Abamectin Resistance in Drosophila

“…Indeed, research involving investigation of the synergistic interactions of enzyme overexpression and/or target-site mutations within a Drosophila-engineered unbiased framework has indicated that the synergistic action of different molecular mechanisms has a multiplicative effect in phenotype manifestation, at least for pyrethroids [44]. This implies that such an experimental system can be readily engineered, for example by stably integrating a TuCPR-expressing transgene together with an attP landing site for ΦC31 integrase or equivalent, which would minimize the "noise" induced by position effects.…”

“…In recent years, functional expression of candidate CYP genes is routinely used for the investigation of their catalytic properties and substrate specificities. Moreover, the integration of the molecular genetics toolbox developed in model systems like Drosophila into insecticide resistance research (reviewed in [39][40][41]) has facilitated novel approaches that have significantly contributed to the validation of several candidate mutations conferring target-site resistance [42], P450 genes potentially conferring metabolic resistance [43], or their synergistic interactions [44], in the absence of confounding genetic effects.…”