A single amino acid polymorphism in the Drosophila melanogaster Dα1 (ALS) subunit enhances neonicotinoid efficacy at Dα1-chicken β2 hybrid nicotinic acetylcholine receptor expressed in Xenopus laevis oocytes.

Polymorphisms are sometimes observed in native insect nicotinic acetylcholine receptor (nAChR) subunits, which are important insecticide targets, yet little is known of their impact on insecticide actions. Here we investigated the effects of a polymorphism involving the substitution of histidine108 by leucine in the Drosophila melanogaster Dα1 subunit on the agonist actions of the neurotransmitter acetylcholine (ACh) and two commercial neonicotinoid insecticides (imidacloprid and clothianidin). There was no significant impact of the H108L substitution on either the ACh EC50, the concentration leading to a half maximal ACh response, or the maximum current amplitude in response at 10 μM ACh, of the Dα1-chicken β2 nAChR expressed in Xenopus laevis oocytes. However, the response amplitudes to imidacloprid and clothianidin were significantly enhanced, indicating a role of His108 in the selective interactions of Dα1 with these neonicotinoids.