The insect GABA receptor, RDL (resistance to dieldrin), is a cys-loop ligand-gated ion channel (cysLGIC) that plays central roles in neuronal signaling and is the target of several classes of insecticides. Many insects studied to date possess one Rdl gene, however, there is evidence of two Rdls in aphids. To further characterize this insecticide target from pests that cause millions of dollars’ worth of crop damage each year, we identified the complete cysLGIC gene superfamily of the pea aphid, Acyrthosiphon pisum, using BLAST analysis. This confirmed the presence of two Rdl-like genes (RDL1 and RDL2) that likely arose from a recent gene duplication. When expressed individually in Xenopus laevis oocytes, both subunits formed functional ion channels gated by GABA. Alternative splicing of RDL1 influenced the potency of GABA and the potency of fipronil was different on the RDL1bd splice variant and RDL2. Imidacloprid and clothianidin showed no antagonistic activity on RDL1 whilst 100 M thiacloprid reduced the GABA responses of RDL1 and RDL2 to 55% and 62%, respectively. It is concluded that gene duplication of Rdl may have conferred increased tolerance to natural insecticides and played a role in the evolution of insect cysLGICs.
del Villar, Silvia G.Jones , Andrew K.
Faculty of Health and Life Sciences\Department of Biological and Medical Sciences
Year of publication: 2018Date of RADAR deposit: 2018-08-01