Effect of norharmane in vitro on juvenile hormone epoxide hydrolase activity in the lower termite, Reticulitermes speratus.

The aromatic beta-carboline norharmane was determined in workers, nymphs, and ergatoids of Reticulitermes speratus (Kolbe) (Isoptera: Rhinotermitidae) by gas chromatography/mass spectrometry. Norharmane levels in workers, nymphs, and ergatoids collected in May (approximately 4.3 ng/termite) were higher than those in November (approximately 0.2 ng/termite). Fluorescence of norharmane was observed in histological sections in whole animals and in the fat body. Norharmane, at a final concentration of 1 mM, stimulated juvenile hormone epoxide hydrolase (JHEH) activity of enzyme extract from ergatoids, but inhibited JHEH activity at higher concentrations. The elevated JHEH activity stimulated by norharmane should accelerate juvenile hormone metabolism in R. speratus.