The Open Entomology Journal

2008, 2 : 1-5
Published online 2008 March 12. DOI: 10.2174/1874407900802010001
Publisher ID: TOENTOJ-2-1

Possible Function of Norharmane in Egg-Laying by Ergatoids and Nymphoids of the Lower Termite, Reticulitermes speratus (Kolbe)

Shuji Itakura , Satoshi Kawabata , Hiromi Tanaka and Akio Enoki
Department of Applied Biological Chemistry, Kinki University, Naka-Machi, Nara, 631-8505, Japan.

ABSTRACT

The aromatic 􀀁-carboline norharmane, which is located in the fat body of Reticulitermes speratus, stimulated the activity of juvenile hormone epoxide hydrolase (JHEH) of larva, ergatoid, and nymphoid homogenates. JHEH activity of ergatoid (16.67 ± 1.30 μU/termite) and nymphoid (20.94 ± 1.64 μU/termite) homogenates fortified with 0.1 mM norharmane was significantly higher than that of ergatoid (9.84 ± 1.69 μU/termite) and nymphoid (16.99 ± 0.60 μU/termite) homogenates to which no norharmane was added. Egg-laying by ergatoids and nymphoids, which ingested norharmane by feeding on norharmane-treated filter paper, was observed in 3 weeks. During rearing on filter paper without norharmane, egg-laying by ergatoids was observed in 5 weeks, whereas no egg-laying by nymphoids was observed throughout the incubation period of 8 weeks. Norharmane seems to be involved in egg development of ergatoids and nymphoids of R. speratus.