Abstract
The attractiveness of Riptortus pedestris males reared in short (10L14D) and long (16L8D) photoperiods to field adults was examined in field trap experiments in autumn. Simultaneously, the pheromone component occurrences and the condition of the internal organs of bait males were clarified by GC-MS analysis and dissection, respectively. In two field experiments, male baits reared in the short photoperiod did not attract any conspecific adults, while males reared in the long photoperiod did. Tetradecyl isobutyrate (14:iBu), which is an essential component of the R. pedestris pheromone, was not detected in any of the extracts of male baits reared in the short photoperiod, while the component was often detected in the extracts of male baits reared in the long photoperiod. In the extracts of 0- to 12-day-old males reared in the short photoperiod in a laboratory, 14:iBu was not detected at all. Males reared in the short photoperiod in the field and laboratory experiments had an immature erection fluid reservoir, indicating that the males entered a reproductive diapause. The present results indicate that photoperiod greatly influences the sexual maturation and pheromone emission of males in R. pedestris.
