Cyclic behavior of plum curculio,Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), within caged dwarf apple trees in spring

From 12 to 19 May 1987, during Morspur apple bloom, 21 radioactively labeled (⁶⁵ Zn) adult plum curculios, Conotrachelus nenuphar (Herbst), were released within a field cage containing four dwarf apple trees and located three times a day. A technique was developed for quickly obtaining (x, y, z)coordinates of location for adults foraging within apple trees. Cyclic patterns of behavior were detected using spectral analysis procedures. Over 70% of plum curculios exhibited diel periodicity with respect to activity and rate of movement, 36% exhibited such periodicity with respect to presence in the trees, and 27% with respect to movements from the center to the periphery of the canopy. Presence in fruit clusters, height in the trees, and movements along east-west and north-south axes showed little or no periodicity. Factors triggering cyclic behavior and practical implications of the results are discussed.