title: Neonicotinoid binding, toxicity and expression of nicotinic acetylcholine receptor subunits in the aphid Acyrthosiphon pisum.
abstract: Neonicotinoid insecticides act on nicotinic acetylcholine receptor and are particularly effective against sucking pests. They are widely used in crops protection to fight against aphids, which cause severe damage. In the present study we evaluated the susceptibility of the pea aphid Acyrthosiphon pisum to the commonly used neonicotinoid insecticides imidacloprid (IMI), thiamethoxam (TMX) and clothianidin (CLT). Binding studies on aphid membrane preparations revealed the existence of high and low-affinity binding sites for [3H]-IMI (Kd of 0.16 ± 0.04 nM and 41.7 ± 5.9 nM) and for the nicotinic antagonist [125I]-α-bungarotoxin (Kd of 0.008 ± 0.002 nM and 1.135 ± 0.213 nM). Competitive binding experiments demonstrated that TMX displayed a higher affinity than IMI for [125I]-α-bungarotoxin binding sites while CLT affinity was similar for both [125I]-α-bungarotoxin and [3H]-IMI binding sites. Interestingly, toxicological studies revealed that at 48 h, IMI (LC50 = 0.038 µg/ml) and TMX (LC50 = 0.034 µg/ml) were more toxic than CLT (LC50 = 0.118 µg/ml). The effect of TMX could be associated to its metabolite CLT as demonstrated by HPLC/MS analysis. In addition, we found that aphid larvae treated either with IMI, TMX or CLT showed a strong variation of nAChR subunit expression. Using semi-quantitative PCR experiments, we detected for all insecticides an increase of Apisumα10 and Apisumβ1 expressions levels, whereas Apisumβ2 expression decreased. Moreover, some other receptor subunits seemed to be differently regulated according to the insecticide used. Finally, we also demonstrated that nAChR subunit expression differed during pea aphid development. Altogether these results highlight species specificity that should be taken into account in pest management strategies.
authors.affiliation: Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647 USC INRA 1330, SFR QUASAV 4207, Université d'Angers, Angers, France.
authors.forename: Emiliane
authors.initials: E
authors.lastname: Taillebois
authors.affiliation: Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647 USC INRA 1330, SFR QUASAV 4207, Université d'Angers, Angers, France.
authors.forename: Abdelhamid
authors.initials: A
authors.lastname: Beloula
authors.affiliation: Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647 USC INRA 1330, SFR QUASAV 4207, Université d'Angers, Angers, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Quinchard
authors.affiliation: Institut de Génétique Environnement et Protection des Plantes (IGEPP), Institut National de la Recherche Agronomique (INRA), UMR 1349, Le Rheu, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Jaubert-Possamai
authors.affiliation: Groupement Interprofessionnel de Recherche sur les Produits Agropharmaceutiques (GIRPA), Angers, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Daguin
authors.affiliation: Institut de Biologie et Technologie (iBiTecS), Service d'Ingénierie Moléculaire des Protéines (SIMOPRO), Commisariat à l'Energie Atomique (CEA), Gif-sur-Yvette, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Servent
authors.affiliation: Institut de Génétique Environnement et Protection des Plantes (IGEPP), Institut National de la Recherche Agronomique (INRA), UMR 1349, Le Rheu, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Tagu
authors.affiliation: Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647 USC INRA 1330, SFR QUASAV 4207, Université d'Angers, Angers, France.
authors.forename: Steeve H
authors.initials: SH
authors.lastname: Thany
authors.affiliation: Laboratoire Récepteurs et Canaux Ioniques Membranaires (RCIM), UPRES EA 2647 USC INRA 1330, SFR QUASAV 4207, Université d'Angers, Angers, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Tricoire-Leignel
mesh_terms: D000818:Animals; D001042:Aphids / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D001665:Binding Sites; D002038:Bungarotoxins / Q000737:chemistry / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D006146:Guanidines / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D007093:Imidazoles / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D007306:Insecticides / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D000073943:Neonicotinoids; D018733:Nicotinic Antagonists / Q000737:chemistry / Q000378:metabolism; D009574:Nitro Compounds / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D010078:Oxazines / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D011485:Protein Binding; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D000077922:Thiamethoxam; D013844:Thiazoles / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity
chemical_list: D002038:Bungarotoxins; D006146:Guanidines; D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D018733:Nicotinic Antagonists; D009574:Nitro Compounds; D010078:Oxazines; D021122:Protein Subunits; D011978:Receptors, Nicotinic; D013844:Thiazoles; C480342:clothianidin; C082359:imidacloprid; D000077922:Thiamethoxam