(Z)-Pentacos-12-ene, an Oviposition-deterring Pheromone of Cheilomenes sexmaculata

Larvae of the coccinellid beetle Cheilomenes sexmaculata (F.) produce an oviposition-deterring pheromone that inhibits egg laying of conspecific females on oviposition sites walked over by first-instar larvae. By use of bioassay-guided fractionation of larval extracts, (Z)-pentacos-12-ene was identified as an active component of the cuticular hydrocarbons of the larvae. Other compounds that occur in the active fractions, such as the alkaloid coccinelline and saturated hydrocarbons, were individually tested but proved to be inactive. The synthesis of (Z)-pentacos-12-ene is reported.