Flight activity ofProstephanus truncatus (Horn) (Coleoptera: Bostrichidae) in relation to population density,resource quality,age, and sex

Higher flight activity has been observed in aged, high-density cultures ofProstephanus truncatus (Horn) (Coleoptera: Bostrichidae), but adults in new, lowdensity culture jars showed less flight activity. In order to understand this change in behavior, the effects of population density, age, resource quality, and sex on the flight ofP. truncatus were studied in a wind tunnel. While an immediate density on the release platform had no significant effect on flight, beetles from high-density cultures were more inclined to fly than those from low-density cultures. Resource quality exerted a major influence on flight; insects in food suitable for boring and oviposition seldomly exhibited flight, however, when food was absent or of inferior quality for boring and oviposition, the dominant behavior was flight. Also, insects maintained for a week in food suitable for boring and oviposition were less ready to fly than those maintained in food unsuitable for boring and oviposition. The optimum age range for flight activity was before the peak of reproduction and insects rarely flew before 4 days or after 32 days of emergence. There were no significant differences between the flight activity of males and that of females. Based on these results, we conclude that age and resource quality are major influences on the flight activity ofP. truncatus and a hypothesis is proposed in which reproductively active male and female beetles disperse from habitats of low resource quality to those that support their reproductive behavior. The practical implications of these results and the possible role of the male-produced aggregation pheromone are discussed.