Age-Dependent Movement Patterns of Japanese Beetle and European Chafer (Coleoptera: Scarabeidae) Grubs in Soil–Turfgrass Microcosms

Abstract

Movement patterns of japanese beetle, Popillia japonica Newman, and European chafer, Rhizotrogus (Amphimallon) majalis (Razoumowsky),grubs as influenced by gravity, host plant position, and external disturbances were studied in laboratory soil-turfgrass microcosms. Second through third instars just before pupation were monitored using radiographic techniques. Neonates were monitored using destructive sampling. Results demonstrate significantly different movement patterns between species and among age groups. The development stage of the grub had a large effect on japanese beetle grub behavior and a measurable, but lesser effect, on European chafers. All larval stages of European chafers and all larval stages of japanese beetle, except neonates and postoverwintering third instars, displayed a downward movement in response to disturbance. Neonate japanese beetles showed little movement while postoverwintering. japanese beetles moved upward when disturbed. European chafer grubs of all age classes displayed random vertical movement with some arrestment in or near sod. Preoverwintering and postoverwintering third-instar chafers showed less dramatic arrestment behavior than other instars tested. Second-instar japanese beetles behaved similarly to European chafers; however, third instars behaved very differently. All third instars except those tested in late winter and early spring showed some innate downward movement in the soil microcosms. japanese beetles tested in late winter displayed random movement with some arrestment in sod, whereas those tested in early spring exhibited upward movement and arrestment in sod.

Soil Application Effects of Metarhizium anisopliae on Japanese Beetle (Coleoptera: Scarabaeidae) Behavior and Survival in Turfgrass Microcosms

“…Boxes with paired microcosms were stored horizontally and at random compass directions, in complete darkness at 25°± 2°C during each experiment. Radiographic techniques and equipment used in this study were identical to those described by Villani and Nyrop (1991). Radiographs were taken of all boxes in sets of eight at regular, predetermined time intervals.…”

Behavioral Interactions Between Japanese Beetle (Coleoptera: Scarabaeidae) Grubs and an Entomopathogenic Nematode (Nematoda: Heterorhabditidae) within Turf Microcosms

“…Grubs tended to move downward in all sections despite greater estimated nematode densities on right sections of the flats. When disturbed, Japanese beetle grubs move downward in the soil profile (Villani & Nyrop 1991).…”

Behavioral Changes in Japanese Beetle and Masked Chafer Grubs (Coleoptera: Scarabaeidae) After Parasitism by Tiphiid Wasps (Hymenoptera: Tiphiidae)

“…Grubs may also burrow downward in response to heat or drought (Villani and Nyrop 1991). Early observations of Tiphia cocoons deep in the soil (McColloch et al 1928) were attributed to the wasps having oviposited after the grubs had begun their normal descent to overwintering or pupation depth (McColloch et al 1928, Clausen 1940.…”