Journal of Chemical Ecology, Vol. 20. No. 12, 1994 CHIRAL ESTERS: SEX PHEROMONE OF THE BAGWORM, Oiketicus kirbyi (LEPIDOPTERA: PSYCHIDAE) MARC RHAINDS, I GERHARD GRIES, t'* JIANXIONG LI, 2 REGINE GRIES, 1 KEITH N. SLESSOR, 2 CARLOS M. CHINCHILLA, 3 and A. CAMERON OEHLSCHLAGER 2 1Centre for Pest Management. Department vf Biological Sciences "Department of Chemistry, Simon Fraser University BurnalLv, British Columbia. Canada V5A IS6 ~Pahn Research Program Palma Tica/ASD de Costa Rica Apdo 30-1000, San Jos~;, Costa Rica (Received March 9, t994; accepted July 20, 19947 Abstract--Gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone extract of female bagworms, Oiketicus kirbyi (Guild- ing), revealed five EAD-active compounds. Retention index calculations. GC- mass spectrometry in both full-scan and selected-ion monitoring modes and GC-EAD analyses of authentic standards identified the compounds as l-methylbutyl octanoate (MBO), l-methylbutyl nonanoate (MBN), I-methylbutyl decanoate (MBD), I-methylpentyl decanoate (MPD), and I-methylbutyl dodecanoate (MBDD). Of these five chiral esters, MBD was most abundant in extracts and elicited the strongest antennal response. In field experiments in Costa Rica, (R)-MBD attracted O. kirbyi males, whereas (S)-MBD in combination with (R)-MBD inhibited response. R but not S enan- tiomers of MBO, MBN, and MBDD strongly synergized attraction to (R)-MBD. (S)-MBO and (S)-MBDD were inactive, whereas (S)-MBN was inhibitory. (R)-, (S)- and racemic MPD were inactive. Blends of (R)-MBD in ternary combination with either (R)-MBO and (R)-MBN or (R)-MBN and (R)-MBDD were as attractive as the five-ester blend. Five- and four-ester blends were equally attractive, suggesting redundancy of pheromone com- ponents for attraction of males. The multiple sex pheromone component blend of chiral esters in O. kirbyi may have evolved to maintain species-specific communication in bagworm communities of tropical Americas. Key Words--Lepidoptera, Psychidae, Oiketicus kirbyi, bagworm, sex pher- *To whom correspondence should be addressed. 3083 0098-0331/94112(.YO-3083~9"JT.O0/O ~'~ 1994 Plenum Publishing Ctlq~imtion