Stick insect chemical biodiversity, biosynthesis and applications (Order Phasmatodea)

Insects make up the most numerous and diverse group of organisms on the planet. This biological diversity also manifests itself in the wide variety of chemical substances they contain. During the past four years my research on the chemical defenses of stick insects (or “phasmids; Order Phasmatodea) has led to several discoveries. This talk will present the following: 1) new insights into phasmid defense spray biosynthesis, 2) compounds discovered in phasmid chemical defenses for the first time, and 3) data demonstrating ant repellent properties of these compounds. The defensive sprays of over 13 phasmid species have been analyzed. From this work, 9 compounds, including spiroketals and dimethylpyrazines, have been identified in stick insects for the first time and at least one novel compound, parectadial, has been discovered. We have shown that sulcatone (from Lopaphus sphalerus) and a spiroketal (from Asceles glaber) repel red imported fire ants (Solenopsis invicta) and mosquitoes. Additionally, we have found that the defensive spray of Anisomorpha buprestoides contains glucosidase and oxidase activity on a putative geraniol glucoside precursor. These results demonstrate that stick insects are promising model systems for studying natural product biosynthesis and chemical biodiversity.