Date of Completion
herbivore-induced plant volatiles, Popillia japonica, Anomala orientalis, Tiphiidae, terpenes, kairomones
Charles S. Henry
Richard J. McAvoy
Field of Study
Doctor of Philosophy
Japanese beetle, Popillia japonica Newman, and oriental beetle, Anomala orientalis (Waterhouse) (Coleoptera: Scarabaeidae) are major turfgrass pests in United States. Tiphia vernalis Rohwer and Tiphia popilliavora Rohwer (Hymenoptera: Tiphiidae) were introduced as biocontrol agents against these beetles. To test the attractiveness of Tiphia wasps to herbivore induced plant volatiles, two choice bio assays were conducted. Results showed that both T. vernalis and T. popilliavora were strongly attracted to volatiles emitted by grub-infested tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.) over healthy grasses. The elevated levels of terpenes emitted by grub-infested Kentucky bluegrass and tall fescue coincided with the attractiveness to the tiphiid wasps. Below-ground host location choice tests revealed that T. popilliavora wasps can successfully discriminate between the trails containing body odor or frass of P. japonica grubs and trails without cues. Host cue detection at varying soil depths experiment revealed that each species of Tiphia can discriminate between the Y-tube arms with and without cues when the cues of P. japonica were buried at a depth of 2 cm but not at a depth of 5 cm. Analysis of Tiphia parasitoids preovipositional behaviors and of their scarab host defensive responses experiment showed that female T. vernalis spent significantly longer time trying to sting A. orientalis grubs than P. japonica grubs in order to paralyze them. Third-instar grubs of A. orientalis spent significantly longer time on defensive behaviors when they were attacked by T. vernalis which likely cause wasps to spend longer time trying to sting A. orientalis grubs. We examined the influence of turfgrass species on development and survival of oriental beetle grubs and their parasitoid T. popilliavora wasps. Grub feeding on perennial ryegrass and endophyte-free tall fescue resulted in highest mean grub survival, weight gain, and number of third instars compared to Kentucky bluegrass. The survival of T. popilliavora larvae was significantly greater on A. orientalis grubs that had been exposed to roots of endophyte-free tall fescue and perennial ryegrass compared to that of Kentucky bluegrass.
Obeysekara, Piyumi T., "Host Selection of Spring Tiphia (Tiphia vernalis) and Summer Tiphia (Tiphia popilliavora), Natural Enemies of Japanese and Oriental Beetles" (2013). Doctoral Dissertations. 295.