The effect of photoperiod on the flight activity and biology of Rhyzopertha dominica (Coleoptera: Bostrichidae)

Patterns of Rhyzopertha dominica (F.) biology were studied at photoperiods of 16:8, 14:10, 12:12, 10:14, 8:16, and 6:18 (L: D). Aspects of biology studied included flight activity of a lab and field strain, and oviposition, egg hatch, developmental time and larval-pupal survival for the lab strain. Egg hatch and larval-pupal survival were unaffected by photoperiod. The longest scotophase significantly delayed development, increased egg production and reduced flight. Oviposition was highest at 8:16. Young females at all photoperiods had a higher rate of oviposition than older females. Flight occurred primarily throughout the photophase, and the number of flights did not vary with sex. Flight activity of 3- and 6-day-old adults was significantly higher than that of 9-day-old adults. Adults from the field strain flew more frequently than those from the lab strain. Time of day did not affect the flight patterns of lab-strain adults, but field-strain adults flew more frequently in the first 2 hr of the photophase at all photoperiods. Based on photoperiod alone, this study suggests that young R. dominica should tend to fly more in the summer during wheat harvest and oviposit more in the late fall, winter and early spring.