Master of Science (MS), Wright State University, 2017, Biological Sciences

Tachinid parasitoids in the subfamily Phasiinae are important natural enemies of heteropteran bugs. Host location by these flies occurs via antennal reception to the pheromones of their hosts; however little is known regarding the mechanisms which underlie host selection. Halyomorpha halys, the invasive brown marmorated stink bug, represents a potential novel host species in North America. This study was conducted to determine the suitability of H. halys as a host for phasiine species, and to assess cues used in host selection by the species Gymnoclytia occidua. Field attraction to pentatomid pheromones by both phasiines and pentatomids in Southwest Ohio were investigated and preliminary laboratory host-selection experiments were conducted. In 2015, from June 23 to September 16 pyramid-type traps were baited with three pentatomid-pheromone lures and were monitored in agricultural and semi-natural locations. Trap catches included specimens from seven different phasiine species and three different pentatomid species. Host movement is an important factor in parasitoid attraction to host models, this attraction was not affected by pheromone presence, choice and no-choice trials indicate that Gymnoclytia occidua females do not discriminate against H. halys. However, no parasitoids were successfully reared from H. Halys. Field parasitism by a Gymnoclytia occidua female on H. halys was directly observed, and both adults and nymphs of H. halys were found bearing parasitoid eggs in the field. These results suggest that H. halys may be a “sink” for Gymnoclytia occidua and possibly other native phasiine parasitoids in North America.

Committee: John Stireman III Ph.D. (Advisor); Donald Cipollini Ph.D. (Committee Member); Jeffrey Peters Ph.D. (Committee Member) Subjects: Animals; Behavioral Sciences; Biology; Ecology; Entomology

Doctor of Philosophy (PhD), Wright State University, 2015, Environmental Sciences PhD

Humans have caused drastic changes in ecosystems and communities through their modification of the natural landscape. Rare species, often highly specialized, are more impacted by these changes. Pieris virginiensis is a rare butterfly native to eastern North America that is a species of concern due to negative influences from habitat loss and plant invasion. This thesis discusses several threats to P. virginiensis, including habitat loss, climate change, competition, and the cascading effects of a novel European invasive plant, Alliaria petiolata, that attracts oviposition but does not allow for larval survival. First, I examined a local extinction event and attributed it primarily to several seasons of poor weather and extreme climatic events, but with contributions by an increasing deer population and the introduction of A. petiolata. Second, I found that A. petiolata attracts approximately two-thirds of total eggs, but no larvae survive on the novel host. I tested several chemical causes of larval death and identified two potential contributors: sinigrin, which delays growth, and alliarinoside, which reduces survival. I also examined competition between P. virginiensis, its host plants, and novel competitors in the habitats. First, I looked at shared habitat use between P. virginiensis and another, exotic Pierid butterfly P. rapae. Although habitats are occasionally shared, P. rapae is most likely not a large influence on the success or failure of P. virginiensis. Second, I examined the influence of A. petiolata when it competes with two native host plants of P. virginiensis, and found differential effects of each life stage of A. petiolata on the native host plants. Finally, I used a combination of species distribution modeling and genetic sequencing to determine the current and future states of P. virginiensis given the changing climate and other stressors on P. virginiensis populations. Although secure currently, future stressors will most likely cause (open full item for complete abstract)

Committee: Don Cipollini Ph.D. (Advisor); John Stireman Ph.D. (Committee Member); Jeffrey Peters Ph.D. (Committee Member); Thaddeus Tarpey Ph.D. (Committee Member); Francie Chew Ph.D. (Committee Member) Subjects: Biology; Botany; Climate Change; Conservation; Ecology; Environmental Science; Environmental Studies

Master of Science, The Ohio State University, 2019, Entomology

Cryptic dispersal, hidden larvae, and long-lived adult stages are among the characteristics of the weevil group that make them difficult to manage. However, it is well known that weevils rely heavily on chemical cues to find hosts and mates, and indeed these cues have been exploited to monitor populations and inform management decisions. A less known and challenging crop-weevil system that would benefit from the investigation of chemical cues is that of the carrot weevil (Listronotus oregonensis) and its cultivated hosts: carrot, celery, and parsley. The majority of carrot weevil research has focused on population management with insecticides, while investigation of carrot weevil behavior or chemical ecology has lagged behind significantly. To address these knowledge gaps I (1) adapted a still-air bioassay approach to evaluate the role of short-range volatile cues in carrot weevil host-seeking behavior, and (2) developed a preliminary degree-day model to understand the emergence activity of overwintering adults in north central Ohio. I found the still-air bioassay to be successful for evaluating carrot weevil response to host volatile odors. Eighty-eight percent of males and 77% of females exhibited attraction to carrot volatiles in the absence of any visual or tactile cues. Similarly, 87% of males were attracted to parsley volatiles in the absence of other cues; however, only 62% of female weevils responded to the volatiles of parsley. Furthermore, male response to parsley volatiles was significantly stronger than that of females. When weevils were given a choice between carrot root and parsley foliage across three experimental dates, male weevils did not exhibit a preference for either host. Females exhibited the same pattern, with the exception of one experimental date wherein 92% of females preferred carrot volatiles over parsley volatiles. Results from two seasons of monitoring overwintering adult activity in the field revealed a consistent 2:1 male-femal (open full item for complete abstract)

Committee: Elizabeth Long (Advisor) Subjects: Entomology