The association between lasionycta wyatti (lepidoptera : noctuidae) and the toxic plant ambrosia chamissonis (asteraceae)

• Main Author: Dojillo-Mooney, Joanna
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/7741

A group of toxic sulfur-containing polyynes (thiarubrines) exhibit significant lightmediated antibiotic activity against microoroganisms particularly against fungi. These phytochemicals have been isolated from several members of the Asteraceae including Ambrosia chamissonis Less. (Greene), a species found along sandy beaches in British Columbia. The larvae of a rare noctuid moth, Lasionycta wyatti (Barnes and Benjamin) (Lepidoptera: Noctuidae), were found to be associated with the stems and roots of this plant. High performance liquid chromatographic (HPLC) analyses of L. wyatti larvae and their frass found significant amounts of thiarubrines. Artificial diets containing thiarubrines were shown to be tolerated by these larvae. These same diets, however, were toxic to larvae ofManduca sexta (L.) (Lepidoptera: Sphingidae) and growth inhibitory to larvae of Spodoptera litura (Hubner) (Lepidoptera: Noctuidae). The combination of simulated sunlight and artificial diets containing thiarubrines, did not negatively affect the larvae of L. wyatti. However, the incorporation of UV-activated thiophenes did negatively affect the larvae of L. wyatti. Results of feeding assays suggest the escape mechanism used by L. wyatti is its ability to rapidly eliminate thiarubrines from its tissues.