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|Title: ||Interaction of Kudzu, Pueraria montana (Lour.) Merr. var. lobata (Willd.) and Arthropods in North Carolina|
|Authors: ||Kidd, Kathleen Ann|
|Advisors: ||David B. Orr, Committee Co-Chair|
David Danehower, Committee Member
Fred Gould, Committee Co-Chair
Joe Neal, Committee Member
|Keywords: ||weed biological control|
insect- plant interaction
|Issue Date: ||11-Feb-2003|
|Abstract: ||This project was undertaken to better understand the ecology of kudzu growing in the United States, and to determine differences between plants from North Carolina and from the native range of this plant, in China. Specific goals of this project were to: 1) evaluate the development and feeding of a native herbivore, Pseudoplusia includens (Walker), the soybean looper, on kudzu and to determine if it could be used as a model herbivore for future studies; 2) determine the rate of seed herbivory at several locations in NC; 3) compare feeding on Chinese and US kudzu by generalist herbivores in the field and the model herbivore in the laboratory; 4) compare the growth and development of kudzu from Chinese and North Carolina seed sources; and 5) examine herbivore-induced volatile production and its effects on predation.
Larvae of P. includens were successfully reared on kudzu, but had higher mortality, longer development times with supernumerary molts, and lower pupal weights compared to larvae reared on soybean. Rearing history affected length of development time, but did not affect other measured parameters. Foliage consumption did not differ between treatments, and nutritional quality of soybean and kudzu did not differ. The stadia at which insects were transferred from artificial diet to either kudzu or soybean significantly influenced development time, number of stadia, foliage consumption, and pupal weights, with the fourth stadia being the optimum stage for transfer. When offered kudzu alone, females readily used it as an oviposition substrate, but when both kudzu and soybean were provided, more eggs were deposited on soybean than on kudzu. Because kudzu is an acceptable host to P. includens this herbivore could be used in future studies as a model herbivore.
Insect herbivory on kudzu seeds was widespread across NC, with 80.9% of unprotected seeds damaged by insect feeding. Feeding by hemipterans caused the most damage statewide, and herbivory by a naturalized bruchid, Borowecious ademptus, was also widespread.
In the field, plants from China had less insect defoliation than plants from the US. In a laboratory bioassay, however, no evidence was found that plants from China were better defended from herbivory than plants from the US. No significant differences were found in preimaginal development times of P. includens, our model herbivore, or in the amount of foliage consumed. By comparison, P. includens fed soybean foliage developed in significantly less time and were larger than those fed on kudzu from either source.
Several growth parameters of kudzu from China and the US were compared in a field study. Vine length, vine dry weights, and the area (m²) covered were greater for kudzu of Chinese origin than for plants of US origin. Although the ratio of root:vine dry weight for plants of Chinese origin was lower than for those of US origin, the ratio of vine dry weight to area covered by the plants was similar for plants from both sources. This suggests that Chinese plants directed more resources to vine growth than root growth, but of those resources directed to the vines, allocation was similar. Fiber content of the roots of Chinese plants was higher than that of US plants. These differences in vine growth and root fibers may be indicative of different varieties or biotypes of kudzu.
Herbivore-induced volatile production was examined in the field and the laboratory. Feeding by the herbivore P. includens resulted in an increase of visits by generalist predators at certain times of the year. Additional methods development is needed to produce conclusive data on volatile production by kudzu and its impact on predation.|
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