Photoperiod and thermoperiod to regulate egg hatching of the short-winged katydid, Chizuella bonneti Bolivar (Orthoptera: Tettigoniidae)

Photoperiod and thermoperiod to regulate egg hatching of the short-winged katydid, Chizuella bonneti Bolivar (Orthoptera: Tettigoniidae)

Creators Arai Tetsuo

The hatchability of the short-winged katydid, Chizuella bonneti (Furukawa, 1950) (Orthoptera: Tettigoniidae) was affected by temperature and photoperiod. It was low at 25ºC and 20ºC in continuous darkness (DD) and constant light (LL), but it increased under LD 12: 12 at 20ºC and 15ºC. The hatchability also increased under thermoperiod (25ºC: 15ºC). The egg hatching was irregular under DD and LL but it occurred in synchronization with photoperiod and thermoperiod. Hatching occurred within 2 h after light-on (L-on) under LD 12: 12 at 25ºC and 20ºC, and under LD 6: 18, 12: 12, and 18: 6 at 15ºC. The effect of the thermoperiod on hatching was also investigated where 25ºC was the warm phase (W) and 15ºC the cool phase (C) conditions both under DD and LL. Under a thermoperiod of WC 6: 18 in DD, hatching peaked within 2 h after the temperature-rise (T-rise) and around 12 h after the temperature-fall (T-fall). Hatching peaked before and after the T-rise under WC 12: 12 and within 2 h after the T-rise under WC 18: 6. In LL, hatching peaked around 8 h and around 6 h after T-fall under WC 6: 18 and 12: 12, respectively, and before and after the T-rise under WC 18: 6. In order to investigate of circadian rhythm in determining hatching time, eggs were transferred from photoperiod or thermoperiod to constant conditions. Hatching occurred in synchronization with photoperiod and thermoperiod but when eggs were transferred to constant conditions, the daily rhythm of hatching disappeared immediately. However, when eggs were transferred to constant conditions, hatching was suppressed for certain periods, suggesting the involvement of an endogenous rhythm triggered by photoperiod or thermoperiod. Hatching time was determined by a single signal of T-fall, but the involvement of a single signal of L-off was not clear. Hatching behavior was triggered by a single signal of L-on or T-rise.

[ISSN]2189-4825