Juvenile hormone titer determinations in the southwestern corn borer, diatraea grandiosella, by electron capture-gas chromatography

A procedure is described for analysis of the three known juvenile hormones (JHs) at physiological levels in 5–10 gram samples of insect hemolymph or whole bodies. The method employs conversion of the oxirane ring of the JHs to their respective 11-methoxy-10-pentafluorophenoxyacetate esters, allowing use of gas-liquid chromatography/electron capture detection for qualitative and quantitative analysis at picogram levels. The method is used to determine the JH titers of the southwestern corn borer, Diatraea grandiosella , as a function of developmental stage. The results show that diapausing larvae contain significant titers of all three known juvenile hormones, thereby supporting the theory that larval diapause in this species is under the control of the corpus allatum.