Insect molecular olfaction

Science programme: Molecular olfaction

Insects use odours as cues to find food and mates.  For example, plants produce odours from tissues such as leaves, flowers and fruit that are used as cues by female moths to locate host plants on which to lay their eggs.  Also female moths produce long range sex pheromones that are detected by males of the same species.  We are interested in understanding how the odour recognition system, housed within the insect’s antennae, functions.  This knowledge will lead to new methods to modify insect behaviour.

Insect genomes contain large numbers of olfactory receptor genes.  Each receptor gene is expressed in a specific class of olfactory sensory neuron that are housed in long hair-like sensilla on the surface of insect antennae.  We are isolating and functionally characterising receptors from insects such as the horticultural pest, Epiphyas postvittana (Light Brown Apple Moth).  We have found that olfactory receptors are functionally active when expressed in insect cell lines.  This is enabling us to determine the range of odorants that each receptor can respond to and test compounds that might block their activation.  We collaborate with researchers from Monash University and CSIRO Entomology  in this programme.

Odorant binding proteins are small molecular weight proteins that are thought to bind and carry odorants to the receptor within the sensillal lymph which bathes the dendrites of the olfactory sensory neurons.  We are characterising the structure and binding activity of odorant binding proteins from E. postvittana to understand their potential role in receptor activation and in encoding specificity within the olfactory system (Newcomb et Al ).  We collaborate with Auckland University in this programme.

Genes involved in the production and recognition of sex pheromones might be involved in the speciation process.  We are testing this hypothesis in moths by comparing DNA sequences and levels of expression in such genes among species within two genera of native New Zealand leafroller moths.  Moths of the genera Ctenopseustis and Planotortrix use a range of similar sex pheromones that mainly vary in the position of a double bond.  We collaborate with researchers from Landcare Research  and Auckland University on this programme.