Neonicotinoid Binding, Toxicity and Expression of Nicotinic Acetylcholine Receptor Subunits in the Aphid Acyrthosiphon pisum
2014
Taillebois, Emiliane | Beloula, Abdelhamid | Quinchard, Sophie | Jaubert-Possamai, Stéphanie | Daguin, Antoine | Servent, Denis | Tagu, Denis | Thany, Steeve H | Tricoire-Leignel, Helene | Récepteurs et Canaux Ioniques Membranaires (RCIM) ; Université d'Angers (UA)-Institut National de la Recherche Agronomique (INRA) | Institut de Génétique, Environnement et Protection des Plantes (IGEPP) ; Institut National de la Recherche Agronomique (INRA)-Université de Rennes (UR)-AGROCAMPUS OUEST | GIRPA ; Groupement Interprofessionnel de Recherche sur les Produits Agropharmaceutiques | Service d'Ingénierie Moléculaire pour la Santé (ex SIMOPRO) (SIMoS) ; Médicaments et Technologies pour la Santé (MTS) ; Université Paris-Saclay-Institut des Sciences du Vivant Frédéric JOLIOT (JOLIOT) ; Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Paris-Saclay-Institut des Sciences du Vivant Frédéric JOLIOT (JOLIOT) ; Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | INRA Département SPE ; Ministère de la Recherche et de l'Enseignement Supérieur
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Show more [+] Less [-]English. 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 [H-3]-IMI (Kd of 0.16 +/- 0.04 nM and 41.7 +/- 5.9 nM) and for the nicotinic antagonist [I-125]-alpha- 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 [I-125]-alpha-bungarotoxin binding sites while CLT affinity was similar for both [I-125]-alpha-bungarotoxin and [H-3]-IMI binding sites. Interestingly, toxicological studies revealed that at 48 h, IMI (LC50 = 0.038 mu g/ml) and TMX (LC50 = 0.034 mu g/ml) were more toxic than CLT (LC50 = 0.118 mu g/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 Apisum alpha 10 and Apisum beta 1 expressions levels, whereas Apisum beta 2 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
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