The roles of hypertrehalosemic hormone on reproduction in modulating trehalose levels and oviposition of the German cockroach, Blattella germanica

Hypertrehalosemic hormone (HTH) is a neuropeptide in the adipokinetic hormone (AKH) family that induces the synthesis of trehalose in most insects such as cockroaches. Trehalose acts as the principle circulating sugar with multiple physiological roles such as energy store. We first determined the daily changes of trehalose amount in the German cockroach, Blattella germanica. Female adults displayed a cyclic fluctuation of hemolymph trehalose levels synchronized with the maturation of oocytes in the reproductive cycle. In this study, we have further cloned the hth gene from the German cockroach and the deduced sequence and organization of preprohormone were compared with other insect AKH precursors. To study the functions of hth in the German cockroach, we performed the RNA interference technique to reduce its expression. The effects of hth dsRNA injection resulted in the less increase of hemolymph trehalose levels in the late period of vitellogenesis in comparison with the control group. In addition, RNAi knockdown of hth also delayed the oviposition and few individuals did not produce ootheca until 15 days after eclosion. The present data supports the recent hypothesis that the peptide of AKH family in insect is in homology of gonadotropin-releasing hormone in other metazoans and its role in reproduction may be conserved.