Lineatin enantiomer preference, flight periods, and effect of pheromone concentration and trap length on three sympatric species of Trypodendron (Coleoptera : Scolytidae)

The effects of lineatin enantiomer ratios, lineatin release rate, and trap length on catches and the night periods of three sympatric species of Trypo dendron Stephens were investigated in field bioassays using multiple-funnel traps. The ambrosia bee tie, Trypodendron betulac Swaine, was caught in si milar numbers in baited traps and blank control traps, showing that this sp ecies does not respond to lineatin. Our results confirmed that Trypodendron lineatum (Olivier) is attracted only to (+)-lineatin. Trypodendron rufitar sus (Kirby) and Trypodendron retusum (LeConte) were shown to utilize lineat in and like T. lineatum were caught only when (+)-lineatin was present. The se results indicate that lineatin does not govern reproductive isolation am ong these three species. There was no effect by (+)-lineatin release rate w ithin the range tested. The flight of T. rufitarsus commenced earlier and c eased before the peak of the T, lineatum flight, suggesting that temporal s eparation may be an important component of reproductive isolation between t hese two species. The flight period of T, retusum was similar to that of T, lineatum. Host odours may aid in reproductive isolation of these two speci es. Enantiomer blend did not significantly affect sex ratio in any species; however; sex ratio differed among species, indicating that different speci es responded differently to the traps or that natural sex ratios differ. Ca tches of T. rufitarsus and T. retusum increased with trap length when phero mone release per trap was held constant and when release was held constant relative to trap length. Trap length and release rate did not affect sex ra tio.