Abstract
Seasonal prevalence of the bean bug, Riptortus clavatus, caught in water-pan traps baited with synthetic aggregation pheromone of this bug was compared with seasonal abundance of the bugs in a soybean field at Tsukuba in 2001. The population density of the adult bugs in the field showed a bimodal pattern with two peaks in mid-August and mid-September. On the other hand, a single peak was observed in the number of adult bugs caught by the pheromone traps in August by a trap placed beside the soybean field and in late September to early October by a trap in the experimental area near glasshouses. The population trend of the adult bugs caught in the traps in the soybean field was not synchronized with that observed in the field. These results suggest that the pheromone traps may not be an effective means to estimate their population trend in soybean fields.
