Abstract
Whole body extracts from nymphs and adults of the brown planthopper, Nilaparvata lugens were analyzed for the known insect juvenile hormones (JHs) by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring. JH was separated successively by solvent extraction, chromatography on an aluminum oxide column and high performance liquid chromatography. JH III was identified as the only type of JH in both stages of this species. As the levels were very low for quantitative determination of JH III by GC-MS, we prepared haemolymph juvenile hormone binding protein (JHBP) of Locusta migratoria which had a high affinity for JH III and used it in a competitive binding assay to quantify JH III in the haemolymph of the brachypterous and macropterous pure lines of N. lugens. However, the JH III titer developmental profiles were similar in the brachypterous and macropterous fifth (final) stadium nymphs. JH III titers in the haemolymph of the brachypters were significantly higher than those of macropters, coinciding with earlier development of oocytes in the brachypters, which supported the regulation of ovarian development by JH III.
