Uncommon C18 Conjugated Dienes Define the Sex Pheromone System of <i>Thelosia camina</i> (Lepidoptera: Apatelodidae), a Pest of Yerba Mate

The yerba mate tree <i>Ilex paraguariensis</i> is widely consumed in South America, and the limited recommendation for pesticide use highlights the need for alternative pest-management strategies. <i>Thelosia camina</i> is an important defoliator whose damage severely reduces yields. This study investigated the sex-pheromone system of <i>T. camina</i> as a basis for pheromone-mediated control. Female pheromone glands were extracted and analyzed by gas chromatography-electroantennographic detection, revealing nine antennally active compounds. Structural elucidation identified three major components (13<i>Z</i>,15<i>Z</i>)-octadeca-13,15-dienal (<b>4</b>), (13<i>Z</i>,15<i>Z</i>)-octadeca-13,15-dien-1-ol (<b>5</b>) and (13<i>Z</i>,15<i>Z</i>)-octadeca-13,15-dien-1-yl acetate (<b>9</b>). Remaining components were stereoisomers and related monoenes consistent with the same double-bond system. All isomers were synthesized, field bioassays showed that both the ternary blend (<b>4</b>,<b>5</b> and <b>9</b>) and the acetate (<b>9</b>) alone attracted males at levels significantly higher than controls. These results confirm conjugated C18 dienes as key pheromone components of <i>T. camina</i> and provide a foundation for pheromone-based, sustainable management in yerba mate cultivation.