Background: Nicotinic acetylcholine receptors (nAChRs) of insects play a key
role in fast excitatory neurotransmission. Several classes of insecticides target insect nAChRs,
which are composed of subunit members of a family of multiple subunit encoding genes. Alternative
splicing and RNA A-to-I editing can add further to receptor diversity. Native and
recombinant receptors have been explored as sites of insecticide action using radioligands,
electrophysiology and site-directed mutagenesis.
Methods: We have reviewed the properties of native and recombinant insect nAChRs, the
challenges of functional recombinant insect nAChR expression, nAChR interactions with
ligands acting at orthosteric and allosteric sites and in particular their interactions with insecticides.
Results: Actions on insect nAChRs of cartap, neonicotinoids, spinosyns, sulfoxamines,
butenolides and mesoionic insecticides are reviewed and current knowledge of their modes of
action are addressed. Mutations that add to our understanding of insecticide action and those
leading to resistance are discussed. Co-crystallisation of neonicotinoids with the acetylcholine
binding protein (AChBP), a surrogate for the nAChR ligand binding domain, has proved instructive.
Toxicity issues relating to insecticides targeting nAChRs are also considered.
Conclusion: An overview of insecticide classes targeting insect nAChRs has enhanced our
understanding of these important receptors and their insecticide binding sites. However, the
subunit composition of native nAChRs remains poorly understood and functional expression
still presents difficulties. These topics together with improved understanding of the precise
sites of insecticide actions on insect nAChRs will be the subject of future research.