Neonicotinoids have been widely used
to control pests
with remarkable
effectiveness. Excessive insecticides have led to serious insect resistance.
Mutations of the nicotinic acetylcholine receptor (nAChR) are one
of the reasons for neonicotinoid resistance conferred in various agricultural
pests. Two mutations, V65I and V104I, were found in the nAChR β1
subunit of two neonicotinoid-resistant aphid populations. However,
the specific functions of the two mutations remain unclear. In this
study, we cloned and identified four nAChR subunits (α1, α2,
α8, and β1) of thrips and found them to be highly homologous
to the nAChR subunits of other insects. Subsequently, we successfully
expressed two subtypes nAChR (α1/α2/α8/β1
and α1/α8/β1) by coinjecting three cofactors for
the first time in thrips, and α1/α8/β1 showed abundant
current rapidly. Acetylcholine, neonicotinoids, and sulfoxaflor exhibited
different activation capacities for the two subtypes of nAChRs. Finally,
V65I was found to significantly reduce the binding ability of nAChR
to neonicotinoids and sulfoxaflor through electrophysiology and computer
simulations. V104I caused a decrease in agonist affinity (pEC50) but an increase in the efficacy (I
max) of nAChR against neonicotinoids and reduced the binding
ability of nAChR to sulfoxaflor. This study provides theoretical and
technical support for studying the molecular mechanisms of neonicotinoid
resistance in pests.