THE EFFECT OF PHOTOPERIOD ON THE FLIGHT ACTIVITY AND BIOLOGY OF RHYZOPERTHA-DOMINICA (COLEOPTERA, BOSTRICHIDAE)

Patterns of Rhyzopertha dominica (F.) biology were studied at photoper iods of 16:8, 14:10, 12:12, 10:14, 8:16, and 6:18 (L:D). Aspects of bi ology studied included flight activity of a lab and field strain, and oviposition, egg hatch, developmental time and larval-pupal survival f or the lab strain. Egg hatch and larval-pupal survival were unaffected by photoperiod. The longest scotophase significantly delayed developm ent, increased egg production and reduced flight. Oviposition was high est at 8:16. Young females at all photoperiods had a higher rate of ov iposition than older females. Flight occurred primarily throughout the photophase, and the number of flights did not vary with sex. Flight a ctivity 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 freq uently in the first 2 hr of the photophase at all photoperiods. Based on photoperiod alone, this study suggests that young R. dominica shoul d tend to fly more in the summer during wheat harvest and oviposit mor e in the late fall, winter and early spring.