CHIRAL ESTERS - SEX-PHEROMONE OF THE BAGWORM, OIKETICUS-KIRBYI (LEPIDOPTERA, PSYCHIDAE)

Gas chromatographic-electroantennographic detection (GC-EAD) analyses of pheromone extract of female bagworms, Oiketicus kirbyi (Guilding), revealed five EAD-active compounds. Retention index calculations, GC-m ass spectrometry in both full-scan and selected-ion monitoring modes a nd GC-EAD analyses of authentic standards identified the compounds as 1-methylbutyl octanoate (MBO), 1-methylbutyl nonanoate (MEN), 1-methyl butyl decanoate (MBD), 1-methylpentyl decanoate (MPD), and 1-methylbut yl dodecanoate (MBDD). Of these five chiral esters, MBD was most abund ant 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 e nantiomers of MBO, MEN, and MBDD strongly synergized attraction to (R) -MBD. (S)-MBO and (S)-MBDD were inactive, whereas (S)-MBN was inhibito ry. (R)-, (S)- and racemic MPD were inactive. Blends of (R)-MBD in ter nary combination with either (R)-MBO and (R)-MBN or (R)-MBN and (R)-MB DD were as attractive as the five-ester blend. Five- and four-ester bl ends were equally attractive, suggesting redundancy of pheromone compo nents for attraction of males. The multiple sex pheromone component bl end of chiral esters in O. kirbyi may have evolved to maintain species -specific communication in bagworm communities of tropical Americas.