Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Biotechnology Science and Engineering

Committee Chair

William N. Setzer

Committee Member

Emmanuel Waddell

Committee Member

Debra M. Moriarity

Committee Member

Bernhard Vogler

Committee Member

Gordon MacGregor


Essences and essential oils., Siloxanes., Opuntia., Organpipe cactus., Drosophila mojavensis., Drosophila melanogaster.


This study investigates the essential oil compositions of certain cacti species native to southern Arizona and the California Channel Islands. The species studied are Opuntia littoralis (Engelm.) Cockerell., Opuntia ficus-indica L. (Mill), Opunita prolifera Engelm., Opuntia acanthocarpa var. major (Engelm. & J.M. Begelow) L.D. Benson, Opuntia phaeacantha var. discata, and Stenocereus thurberi Engelm. Drosophila mojavensis, a cactus fly, utilizes the necrotic rots of O. littoralis and S. thurberi, which have been shown to be toxic to fruit flies, Drosophila melanogaster. The oil compositions of both O. littoralis and S. thurberi was characterized at differing states of necrosis and compared to laboratory rot specimens. Toxicity analysis was performed on Drosophila melanogaster to ascertain toxicity to individual volatile compounds identified in the necrotic cactus rots. Specimens of O. littoralis, O. ficus-indica, and S. thurberi were examined for the presence of cyclic oligosiloxane compounds. These cyclic compounds were characterized by gas chromatography-mass spectrometry. Confocal microscopy was employed to identify the location of silica bodies in the cactus tissues.



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