Highly selective tuning of a silkworm olfactory receptor to a key mulberry leaf volatile

Curr Biol. 2009 Jun 9;19(11):881-90. doi: 10.1016/j.cub.2009.04.035. Epub 2009 May 7.


Background: The olfactory system plays an important role in the recognition of leaf volatiles during the search of folivore insects for a suitable plant host. For example, volatiles emitted by mulberry leaves trigger chemotaxis behavior in the silkworms Bombyx mori, and as a consequence, they preferentially reside on and consume mulberry leaves. Here, we aimed to identify natural chemoattractants and their corresponding olfactory receptors (Ors) involved in silkworm behavior to mulberry leaves.

Results: Chemotaxis behavioral assays for headspace volatiles detected by gas chromatography-mass spectroscopy analysis revealed that among the volatiles that were emitted by mulberry leaves, cis-jasmone was the most potent attractant for silkworms, working at a threshold of 30 pg from [corrected] 20 cm distance. Among a total of 66 Ors identified in the B. mori genome, we found that 23 were expressed in the olfactory organs during larval stages. Functional analysis of all the larvae-expressed Ors in Xenopus oocytes revealed that one Or, termed BmOr-56, showed a high sensitivity to cis-jasmone. In addition, the ligand-receptor activity of BmOr-56 reflected the chemotaxis behavioral response of silkworms.

Conclusions: We identified cis-jasmone as a potent attractant in mulberry leaves for silkworms and provide evidence that a highly tuned receptor, BmOr-56, may mediate this behavioral attraction. The current study sheds light on the mechanism of the correlation between olfactory perception in folivore insects and chemotaxis behavior to a natural volatile emitted by green leaves.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bombyx / drug effects
  • Bombyx / genetics
  • Bombyx / physiology*
  • Chemical Fractionation
  • Chemotactic Factors / chemistry*
  • Chemotactic Factors / isolation & purification
  • Chemotaxis / drug effects
  • Chromatography, Gas
  • Feeding Behavior
  • Larva / drug effects
  • Larva / physiology
  • Morus / chemistry*
  • Oils, Volatile / chemistry*
  • Phylogeny
  • Plant Leaves / chemistry
  • Receptors, Odorant / genetics
  • Receptors, Odorant / physiology*
  • Structure-Activity Relationship
  • Xenopus


  • Chemotactic Factors
  • Oils, Volatile
  • Receptors, Odorant