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Previous studies have shown that: (1) plant defensive compounds may have medicinal properties; and (2) defensive compounds present in aposematic insects are often sequestered from their host-plant(s). This study addresses whether aposematic insects can be used as guides to detect plants containing medicinally-active compounds. First, ten tropical medicinally-active plants and ten non-active plants, selected using previous ICBG bioassay results, were observed regularly to determine their insect populations. Aposematic insects were found more frequently on active than non-active plants ( X2=8.167, P=0.01). Second, three aposematic insects feeding on Tithonia diversifolia were examined chemically to determine the fate of the plant's pharmaceutically-active compounds. They were not found to sequester or excrete these compounds. Therefore, using aposematic insects could increase the likelihood of finding plants with medicinally-active compounds; however, these insects may not necessarily utilize these compounds for defensive purposes. The underlying basis for this significant association between aposematic insects and medicinally-active plants requires further investigation.

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 201-241). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph.D.) -- University of Adelaide, Dept. of Entomology, 1980.

Thesis (Ph.D.)--Michigan State University. Dept. of Entomology and Program in Ecology, Evolutionary Biology, and Behavior, 2008. / Title from PDF t.p. (viewed on July 17, 2009) Includes bibliographical references (p. 115-126). Also issued in print.

Thesis (Ph. D.) -- Lincoln University, 2008. / Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Ulrich G. Mueller. Vita. Includes bibliographical references.

Thesis (Ph. D.) -- Lincoln University, 2008. / Also available via the World Wide Web.

The response to host plant variation shapes the long-term success of phytophagous insects. Two gall-forming tephritid flies, Urophora affinis and U. quadrifasciata, oviposit in flower buds of Centaurea diffusa and C. maculosa (Asteraceae). Females of both fly species chose among plants, among groups of buds on plants, and among buds. Among plant choices were correlated with buds per plant. Among bud choices corresponded to larval developmental requirements. Insect attack led to gall formation, bud abortion, and reduced seed production. Bud abortion, caused by probing females, limited gall densities. Increased densities of U. affinis females relative to oviposition sites led to more U. affinis galls, increased bud abortion, fewer U. quadrifasciata galls, and fewer seeds. A temporal refuge for seed production was observed. Plants compensated only slightly for aborted buds. Bud abortion may increase the search time between successful ovipositions. A simulation model based on this premise implied that bud abortion may dramatically reduce total gall formation. Plant quality was manipulated in an attempt to shift three population limiting factors. Plants responded to fertilization and watering with an increase in bud numbers. Except for two year-site-treatment combinations, galls per developed bud did not differ significantly between treatments. Treated plants did not differ in their propensity to abort buds. U. affinis larvae developed faster in fertilized plants. Among year comparisons showed that the density of buds available for oviposition was limited by precipitation, non-random insect attack, and, in the longer term, by the reduction in seed production due to fly attack. Bud densities, in turn, limited gall densities. / Science, Faculty of / Zoology, Department of / Graduate