Proximity of release points of pheromone components as a factor confusing males of the spotted stem borer,Chilo partellus, approaching the trap.

The effect of proximity of the release points of the two pheromone components (Z)-11-hexadecenal and (Z)-11-hexadecen-1-ol of the spotted stem borer,Chilo partellus (Lepidoptera: Pyralidae) on behavior of the males and on trapping efficiency was investigated. Separating the dispensers of the two components in the trap by a mere 3 cm resulted in a threefold decrease in trap performance, compared to very close release of the components. The result is attributed to possible distortion of the pheromone signal, resulting in confused behavior ofC. partellus males in the vicinity of the trap. The ethological and practical implications of the phenomenon are discussed.