Journal of Insect Physiology 50 (2004) 547–554 www.elsevier.com/locate/jinsphys The diapause hormone-pheromone biosynthesis activating neuropeptide gene of Helicoverpa armigera encodes multiple peptides that break, rather than induce, diapause Tian-Yi Zhang a , Jiu-Song Sun a , Qi-Rui Zhang a , Jun Xu a , Rong-Jing Jiang c , Wei-Hua Xu a,b, a Department of Molecular and Cell Biology, University of Science and Technology of China, Hefei 230027, China b State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, China c Shanghai Institute of Entomology, Chinese Academy of Science, Shanghai 200025, China Received 20 October 2003; received in revised form 10 March 2004; accepted 15 March 2004 Abstract FXPRLamide peptides encoded by the DH-PBAN (diapause hormone-pheromone biosynthesis activating neuropeptide) gene induce embryonic diapause in Bombyx mori, but terminate pupal diapause in Helicoverpa armigera (Har). Here, we explore the mechanisms of terminating pupal diapause by the FXPRLamide peptides. Using quantitative RT-PCR, we observed that expression of Har-DH-PBAN mRNA in the SG of nondiapause-type pupae was significantly higher than in diapause-type pupae. Immunocytochemical results indicated that the level of FXPRLamide peptides and axonal release are related to the diapause decision. Ecdysteroidogenesis in prothoracic glands (PGs) was stimulated by synthetic Har-DH in vivo and in vitro, and labeled Har-DH bound to the membrane of the PG, thus suggesting that DH breaks diapause by activating the PG to synthesize ecdy- sone. Furthermore, the response of DH in terminating diapause was temperature dependent. Decerebration experiments showed that the brain can control pupal development through the regulation of DH, and DH can terminate diapause and promote devel- opment without the brain. This result suggests a possible mechanism of response for the signals of DH and other FXPRLamide peptides in H. armigera. # 2004 Elsevier Ltd. All rights reserved. Keywords: DH-PBAN; Pupal diapause; Ecdysteroid; Diapause termination; Pupal development; Helicoverpa armigera 1. Introduction Diapause is a period of arrested development that has evolved as an adaptation to survive seasonally recurring adverse conditions. As a strategy for over- wintering and synchronization, insects can enter diapause at various developmental stages, depending on the species. Diapause is a complex adaptive response that involves many well-defined biochemical, physiological, and endocrinological adjustments (Denlinger, 1985; Yamashita and Hasegawa, 1985), yet many aspects of diapause regulation remain unknown (Denlinger, 2002). Roles for many of the well-known insect hormones, including ecdysone, juvenile hormone, and prothoracicotropic hormone (PTTH), have been well defined, and thus far no unique hormone has been associated with diapause termination (Denlinger, 1985, 2002; Denlinger et al., 1980). By contrast, a specific gene has been associated with diapause induction in the silkworm, Bombyx mori. This species has an embryonic diapause that is induced by diapause hormone (Bom-DH), a member of the FXPRLamide family of peptides produced by neurose- cretory cells in the suboesophageal ganglion (SG) (Imai et al., 1991; Yamashita, 1996). The Bom-DH cDNA encodes DH, pheromone biosynthesis activating neuropeptide (PBAN) and three SG neuropeptides  Corresponding author. Tel.: +86-551-3602234; fax: 86-551- 3601443. E-mail address: whxu@ustc.edu.cn (W.-H. Xu). 0022-1910/$ - see front matter # 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jinsphys.2004.03.011