Tenellin is a yellow pigment produced by species of the genus Beauveria, isolated and reported by Canadian researchers in 1968. Structure elucidation in 1977 showed that tenellin belongs to the rare 4-hydroxypyridone class containing a dienone side chain. Little has been published on the biological activity of tenellin despite the extensive use of Beauveria species, capable of producing tenellin, as biocontrol agents for agrochemical pests.