Silencing ofP‐glycoproteinincreases mortality in temephos‐treatedAedes aegyptilarvae

Abstract

Re-emergence of vector-borne diseases such as dengue and yellow fever, which are both transmitted by the Aedes aegypti mosquito, has been correlated with insecticide resistance. P-glycoproteins (P-gps) are ATP-dependent efflux pumps that are involved in the transport of substrates across membranes. Some of these proteins have been implicated in multidrug resistance (MDR). In this study, we identified a putative P-glycoprotein in the Ae. aegypti database based on its significantly high identity with Anopheles gambiae, Culex quinquefasciatus, Drosophila melanogaster and human P-gps. The basal ATPase activity of ATP-binding cassette transporters in larvae was significantly increased in the presence of MDR modulators (verapamil and quinidine). An eightfold increase in Ae. aegypti P-gp (AaegP-gp) gene expression was detected in temephos-treated larvae as determined by quantitative PCR. To analyse the potential role of AaegP-gp in insecticide efflux, a temephos larvicide assay was performed in the presence of verapamil. The results showed an increase of 24% in temephos toxicity, which is in agreement with the efflux reversing effect. RNA interference (RNAi)-mediated silencing of the AaegP-gp gene caused a significant increase in temephos toxicity (57%). In conclusion, we have demonstrated for the first time in insects that insecticide-induced P-gp expression can be involved in the modulation of insecticide efflux.

ABC transporters are involved in defense against permethrin insecticide in the malaria vector Anopheles stephensi

“…In mosquitoes, the ABCB2 gene was showed by quantitative PCR to be eightfold up-regulated in larvae of a susceptible strain of Ae. aegypti analysed at 48 h post temephos-treatment [29]. The ABCB4 gene was showed to be over-transcribed by transcriptome and quantitative PCR analyses, in DDT and pyrethroid (permethrin and deltamethrin) resistant Ae.…”

“…stephensi , we performed bioassays using a sub-lethal dose of the ABC transporter inhibitor verapamil in association with permethrin. The results obtained using this approach highlight that the combination of insecticides with an ABC-transporter inhibitor can increase the efficacy of the insecticide molecule [18, 29, 55]. In prospect, combined treatments of insecticide plus ABC-transporter inhibitors could be proposed, with the objective of reducing the current dosages of insecticides or to prevent the development of resistance, and reduce environmental pollution [29, 56].…”

“…The results obtained using this approach highlight that the combination of insecticides with an ABC-transporter inhibitor can increase the efficacy of the insecticide molecule [18, 29, 55]. In prospect, combined treatments of insecticide plus ABC-transporter inhibitors could be proposed, with the objective of reducing the current dosages of insecticides or to prevent the development of resistance, and reduce environmental pollution [29, 56]. The implementation of such a strategy would require the availability of gene- and species-specific inhibitors in order to avoid the serious consequences that would derive from a generic inhibition of ABC-transporters in non-target organisms.…”

“…stephensi at the third instar were exposed to permethrin and the expression of ABC-transporter genes was monitored in the surviving larvae by quantitative RT-PCR twice after insecticide treatment: 24 h (e.g. the time at which the LD50 has been estimated) and 48 h following the study of Figueira-Mansur [29] that found increased expression of ABC transporters in the mosquito Ae. aegypti .…”

Transcriptome mining: Multigene panel to test delousing drug response in the sea louse Caligus rogercresseyi

“…The present study showed an overregulation of P-gp in C. rogercresseyi treated with azamethiphos that was significantly greater than the response obtained in adults treated with deltamethrin, thus demonstrating a strong interaction of P-gp with organophosphates. Likewise, when the expression of P-gp was blocked in A. aegypti via RNAi, an increased susceptibility to the temephos drug was triggered (Figueira-Mansur et al, 2013). On the other hand, an interaction between P-gp and deltamethrin in C. rogercresseyi cannot be ruled out as an increased expression of P-gp was observed with a 2 ppb concentration of deltamethrin.…”