The effects of photoperiod and temperature on diapause termination in Thyrassia penangae (Lepidoptera: Zygaenidae)

Author of the article:LIU Wei1** SONG Shui-Lin1 GE Hong-Bin2 XUE Fang-Sen1 HE Hai-Min1***

Author's Workplace：1. Institute of Entomology, Jiangxi Agricultural University, Nanchang 330045, China; 2. Nanchang Academy of Agricultural Sciences, Nanchang 330038, China

Key Words：Thyrassia penangae; photoperiod; temperature; diapause termination

Abstract：[Aim] To investigate the effects of photoperiod and temperature on diapause induction and termination in Thyrassia penangae. [Methods] Diapausing cocoons were randomly assigned to different temperature and photoperiod treatments after which their diapause and eclosion durations were measured and compared. [Results] Exposure to photoperiods of 11L∶13D, 12L∶12D and 13L∶11D at 22, 25 and 28 ℃ did not significantly affect diapause duration (P = 0.604). However, when diapausing cocoons were placed under 12L∶12D at 25 ℃, or 15L∶9D at 22, 25 and 28 ℃, the duration of diapause significantly shortened with increasing temperature, from (135.23 ± 2.22) d at 22 ℃ to (101.55 ± 4.15) d at 28 ℃ (P < 0.001). The eclosion duration of diapausing cocoons tended to shorten at 5 ℃. The eclosion duration of diapausing cocoons at normal ambient temperatures was 117 days, whereas that of cocoons exposed to low temperatures for 30, 60 and 90 d was 96, 75 and 47 d, respectively. [Conclusion] Photoperiod and temperature significantly affected the duration of diapause and eclosion in T. penangae. These results further understanding of the insect diapause-termination mechanism.