Sunday, April 24, 2011

The Importance of Being Smelly

Scents plays very important roles in the life of a moth. Recognising food is one. Some moths can distinguish individual scents that indicate food rewards from cocktails of more than sixty floral scents (1), and the hawkmoth Manduca sexta will not feed on a flower when the appropriate scent has been removed, even if the visual floral signal is still present and correct (2).
Angle Shades Moth, Phlogophora meticulosa
Of possibly more pressing concern however is the role scents play in mating of moths. Take the Angle Shades moth (Phlogophora meticulosa) for example. This noctuid moth is commonly seen in Ireland from May to October and is easily recognisible by the ragged margin of its forewing, with a leading edge rolled in at rest (3). The olive green to brown wings show pinkish triangular marks. Mating for the Angle Shades takes place at dawn, when the males remain at rest until the females expose their scent organs to release pheremones (4). The male then flies around the female, dousing her with burst of his own pheremones which seem to act jointly as an arrestant, preventing her from flying away, and an aphrodesiac, to persuade her to accept him as a mate (5). The pheremones in males are released from structures that are known as hair pencils. Scent plays such a vital role in P. meticulosa mating that removal of these results in an inability of males to mate (6).

Angle Shades Moth, Phlogophora meticulosa
  1. Riffell et al. 2009, Proceedings of the National Academy of Sciences of the USA 106 pp. 19219-19226
  2. Raguso and Willis 2002, Animal Behaviour 64 pp. 685-695
  3. Sterry 2004, Collins Complete Guide to Irish Wildlife p. 116
  4. Burton and Burton, 2002 The International Wildlife Encyclopedia p. 1822
  5. Preton-Mafham and Preston-Mafham 1993 The Encyclopedia of INvertebrate Behaviousr p. 105
  6. Birch et al. Annual Review of Entomology 1990 35 pp. 25-58

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