Sex pheromone components of nettle caterpillar, Setora nitens

Gas chromatographic-electroantennographic detection (GC-EAD) analyses of ph eromone gland extracts of Female nettle caterpillars, Setora nitens, reveal ed four compounds that consistently elicited responses from male moth anten nae. Retention indices on three fused silia columns (DB-5, DB-23, and DB-21 0) of two EAD-active compounds were almost identical to those of (E)-9-dode cenal (E9-12: Aid) and (E)-9,11-dodecadienal (E9,11-12: Aid), two pheromone components previously identified in congeneric Setothosea asigna. However, comparative GC, CC-EAD, and GC-mass spectrometry of extracted S. nitens co mpounds and authentic standards revealed that the candidate pheromone compo nents were (Z)-9-dodecenal (Z9-12:Ald) and (Z)-9,11-dodecadienal (Z9,11-12: Aid). The two other EAD-active compounds in pheromone gland extracts proved to be the corresponding alcohols to these aldehydes. In field-trapping exp eriments in Tawau, Malaysia, synthetic Z9-12:Ald and Z9,11-12:Ald at a 1:1 ratio, but not singly, attracted male S. nitens. Attractiveness of these tw o aldehydes could not be enhanced through the addition of their correspondi ng alcohols. Whether these differences in pheromone biology and chemistry b etween S. nitens and S. asigna are sufficient to prevent cross-attraction o f heterospecific males or whether nonpheromonal mechanisms are required to maintain reproductive isolation is currently being studied.