The pine caterpillar, Dendrolimus punctatus (Walker) (Lepidoptera: Lasiocampidae), is a multivoltine pest of pine trees in China, overwintering as larvae. Winter diapause was induced by short day length. The critical night length was about 10 h 40 min at 25, 28, and 31°C in the field, showing a temperaturecompensated diapause induction. Transfer experiments from a short night (L16: D8) to a long night (L12: D12) or vice versa at different times after hatching showed that sensitivity to day length was restricted to the first 14 days; the required day number for a 50% response at 25°C was about 3.5 days for short nights but 7.5 days for long nights, indicating that short nights are photoperiodically more effective. When four successive short nights (L16: D8) were used to interrupt the long-night regime (L12: D12) at different development stages and vice versa, the results showed that the highest sensitivity to photoperiod occurred on the 4th−8th day, corresponding to the second larval instar. Experiments of alternating short-night (L16:D8) and long-night (L12:D12) cycles during the larval period showed that the information of short nights as well as long nights could be accumulated. By rearing the larvae under conditions other than 24-h light–dark cycles, we clearly showed that the dark period (scotophase) played a major role in the determination of diapause. The Nanda-Hamner and Bünsow experiments failed to reveal rhythmic fluctuations with a period of about 24 h in the occurrence of diapause. Therefore, the photoperiodic clock in D. punctatus is an hourglass timer or a damped circadian oscillator.

大猿叶虫Colaphellus bowringi是江西山区十字花科蔬菜上的重要食叶害虫，以成虫在土中越夏和越冬。由于成虫滞育期的差异，该虫的化性显示了明显的种内变异。有些个体隔年繁殖；有些个体是一化性的，仅在春季或秋季繁殖1代；有些个体是二化性的，春季和秋季各繁殖1代；有些个体是多化性的，春季1代，秋季2～3代。因此，大猿叶虫在田间一年可发生4代。在春季，滞育成虫于2月底至4月初陆续出土繁殖；在秋季，滞育成虫于8月中旬至10月初陆续出土繁殖。春季羽化的成虫于4月底至6月上旬陆续入土越夏，秋季羽化的成虫于9月中旬至12月底陆续入土越冬。大猿叶虫一生能交配多次，大多数雌虫的产卵期超过1个月，最长达67天。平均每雌产卵量；春季世代为644粒，秋季世代为963粒，最高达1950粒。各虫态的发育历期：在15～30℃间，卵为13.78～3.14天，幼虫为22.83～6.95天，蛹为12.10～3.18天。发育阈值温度：卵为10.7 ℃，幼虫为8.8 ℃，蛹为9.6 ℃。非滞育成虫的寿命约为1～2个月，滞育成虫的寿命为5～38个月。滞育成虫均入土蛰伏，在土中的蛰伏深度为9～31cm。

Pseudopidorus fasciata enters diapause as fourth instar larvae at short day lengths. Using 24-h light–dark cycles, the photoperiodic response curves in this species appeared to be similar with a critical night length of 10.5 h at temperatures below 30▫C. At an average temperature of 30.5▫C, the critical night length had shifted to between 15 and 17 h. In experiments using non-24-h light-dark cycles, it was clearly demonstrated that the dark period (scotophase) was the decisive phase for a diapause determination. In night interruption experiments using 24-h light–dark cycles, a 1-h light pulse at LD12:12 completely reversed the long night effect and averted diapause in all treatments.. At LD 9:15 light pulses of 1-h, 30- or 15-min also averted diapause effectively when both the pre-interruption (D1) or the post-interruption scotophases (D2) did not exceed the critical night length. If D1 or D2 exceeded the critical night length diapause was induced. The most crucial event for the photoperiodic time measurement in this species is the length of the scotophase. A 10-min light pulse placed in the most photosensitive phase reversed diapause in over 50% of the individuals. Night interruption experiments under non-24-h light–dark cycles indicated that the photoperiodic clock measured only D1 regardless of the length of D2, suggesting that the most inductive cycles are often those in which LD are close to 24 h. In resonance experiments, this species showed a circadian periodicity at temperatures of 24.5 or 26▫C, but not at 30.5 and 23.3▫C. On the other hand, Bünsow and skeleton photoperiod experiments failed to reveal the involvement of a circadian system in this photoperiodic clock. These results suggest the photoperiodic clock in this species is a long-night measuring hourglass and the circadian effect found in the final expression of the photoperiodic response in the resonance experiments may be caused by a disturbing effect of the circadian system in unnatural regimes.

w a great difference in diapause duration (from several months to more than 3 years) under natural conditions. The effects of diapause duration on future reproduction in the beetle are investigated at 25▫C with an LD 14: 10 h photoperiod and under natural conditions. The fecundity of postdiapause adults with a short diapause of 5 months and nondiapause adults is similar, showing that a short diapause has no affect on reproduction, whereas the longevity of postdiapause adults with a short diapause of 5 months is significantly shorter than nondiapause adults, showing that a short diapause has a negative affect on longevity. The mean total egg production per female and longevities of postdiapause adults with long diapause periods of 16, 22, 29 and 34 months are similar to nondiapause adults, but the mean daily egg production per female is significantly higher than nondiapause adults, showing that extended diapause has a positive effect on postdiapause reproduction. The offspring of postdiapause parents require a relatively shorter time for egg development compared with the offspring of nondiapause parents, showing that diapause has a positive effect on their offspring’s performance. However, there are no significant differences among offspring performance in terms of survival, adult longevity, mean egg production per female and mean daily egg production per female.

本文报道了用水稻和茭白分别饲养二化螟水稻种群和茭白种群的光周期反应。光周期反应曲线显示,用水稻饲养茭白种群或用茭白饲养水稻种群,无论是在短光照还是在长光照条件下,绝大多数幼虫被诱导进入滞育,丧失了各自原有的光周期反应特性,表明这两个种群已分化到仅适应其本身寄主的程度。用水稻饲养的茭白种群仅有5%～6%的个体化蛹,且其幼虫期较用茭白饲养的延长了15～18天;而用茭白饲养的水稻种群有30 %～40 %的个体化蛹,其幼虫期与水稻饲养的仅相差3～8天。茭白种群用水稻饲养时32日龄幼虫体重仅为茭白饲养的53.1 % ,而水稻种群用水稻饲养时32日龄幼虫体重为茭白饲养的79.5 %。这些结果表明,茭白种群不适应取食水稻,而水稻种群对取食茭白则有一定的适应能力。根据这些结果,我们认为: (1) 这两个种群已出现种下分化的迹象; (2) 茭白种植不会对水稻田二化螟的发生产生大的影响。