Variation in the production and distribution of substituted benzoquinone compounds among genetic strains of the confused flour beetle, Tribolium confusum

Insects often produce chemicals, such as defensive compounds, whose quantit y and distribution can affect their fitness. For evolution to produce adapt ations, chemical production must be genetically variable. Here we report th e results of a study using high-performance liquid chromatography to quanti fy two important chemical secretions of the flour beetle Tribolium confusum , methyl-1,4-benzoquinone (MBQ) and ethyl-1,4-benzoquinone (EBQ). Our resul ts show a distinct difference in the production of the compounds among four genetically distinct strains of T confusum (b-+, b-I, b-IV, b-Pakistan) wi th an unusually high amount measured for the b-Pakistan strain. By measurin g internal and external benzoquinone levels separately, we were also able t o detect differences in production and distribution of the compounds betwee n the strains. Some strains secrete more of the chemicals, whereas other st rains appear to sequester the compounds within their bodies. The sexes also differ in total quinone production as well as in their internal to externa l benzoquinone ratios, suggesting the trait is sex influenced. Finally, a c onsistent correlation in the amounts of MBQ to EBQ in individual beetles su ggests that the substituted benzoquinones share a common precursor or pathw ay.