Alpha-Terthienyl is a pigment in African marigolds (Tagetes spp.) and exhibits antifungal, insecticidal, and nematicidal properties related to its ability to sensitize the formation of singlet oxygen. Terthiophene is the compound responsible for the insecticidal activity of Tagetes minuta. Alpha-Terthienyl is also used as building block in the production of organic semiconductors.