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Description
The Bogong moth Agrotis infusa is a long-distance nocturnal migrant whose navigational ability still remains only partly understood. They travel up to a thousand kilometres to the Australian Alps where they seek out the shelter of isolated cool alpine caves, thereby escaping the approaching summer heat of their breeding grounds. Once in the caves, they enter a state of dormancy over the coming summer (known as aestivation). How they find their aestivation caves is still a mystery. Our hypothesis is that at the end of their journey, during the final “pin-pointing phase” of their long-distance navigation, they use their olfactory system to home in on their cave destination. If this is true it would possibly be the first proof of an innate “homing” olfactory cue.
We investigated the olfactory system of the Bogong moth to address this hypothesis by using odour collections from the caves (analysed in a gas chromatograph-mass spectrometer), electrophysiological recordings from the antennae and behavioural experiments. When analysing cave odours, one compound - (Z,E)-9,12-tetradecadienyl acetate - was found that males strongly react to electrophysiologically and both sexes behaviourally. During the spring migration towards the caves they are significantly attracted to this compound, but when leaving the caves on their return journey in the autumn, they are indifferent to it. The origin of this compound remains unknown. However, the three likeliest sources are the moths themselves, microbial activity in the soil or one or both species of parasitic mermithid nematodes that live only in these caves.
