Larval diapause of Monochamus urussovi and photoperiodic effects on larval development in tree bolts

To determine the larval diapause and the effect of photoperiod on development in Monochamus urussovi (Coleoptera: Cerambycidae), larvae were reared on Abies sachalinensis and Picea jezoensis logs and bolts. Larvae stopped developing in the final instar at 25°C and 16L : 8D (16 h light and 8 h dark) whereas an exposure to 5°C in the dark (134 days) following acclimation at 12°C under natural daylength led to adult emergence. When larvae were reared under 8L : 16D or 16L : 8D at 25°C with an intervening period of chilling at 5°C in the dark (112 days), a photoperiod of 8L : 16D induced a shorter time required for adult emergence after being returned to 25°C, and smaller adult body size than 16L : 8D.     

The effect of temperature on photoperiodic induction of diapause in insects and mites: a model for the photoperiodic "counter"

Existing models for the accumulation of photoperiodic information (the photoperiodic "counter") cannot explain satisfactorily the various effects of temperature on diapause induction in insects and mites, nor the observation that in several insect species the so-called "required day number" has a high degree of temperature compensation. In the model presented in this paper the effect of temperature has been incorporated in such a way that both the rate of increase of the "induction sum" (or "diapause titre") and the level of the "minimally required induction sum" (or "threshold level") are temperature dependent. The proposed model is in accordance with observed temperature effects, and gives an explanation for a temperature-compensated "required day number".     

Insect photoperiodism: effects of temperature on the induction of insect diapause and diverse roles for the circadian system in the photoperiodic response

This review considers the effects of temperature on insect diapause induction and the photoperiodic response, and includes constant temperature, temperature cycles, pulses and steps in daily light–dark cycles, constant darkness and in constant light, all with reference to various circadian‐based “clock” models. Although it is a comparative survey, it concentrates on two species, the flesh fly Sarcophaga argyrostoma and its pupal parasite Nasonia vitripennis, which possess radically different photoperiodic mechanisms, although both are based upon the circadian system. Particular attention is given to the effects of daily thermoperiod in darkness and to low and high temperature pulses in conjunction with a daily light–dark cycle, treatments that suggest that S. argyrostoma “measures” night length with a “clock” of the external coincidence type. However, N. vitripennis responds to seasonal changes in photoperiod with an internal coincidence device involving both “dawn” and “dusk” oscillators. Other species may show properties of both external and internal coincidence. Although the precepts of external coincidence have been well formulated and supported experimentally, those for internal coincidence remain obscure.     

Inheritance patterns of photoperiodic diapause induction in Leptinotarsa decemlineata

Photoperiod is a reliable indicator of season and an important cue that many insects use for phenological synchronization. Undergoing range expansion insects can face a change in the local photoperiod to which they need to resynchronize. Rapid range expansion can be associated with rapid photoperiodic adaptation, which can be associated with intense selection on strongly heritable polygenic traits. Alternatively, it is proposed that, in insects with an XO sex‐determination system, genes with large effect residing on the sex chromosome could drive photoperiodic adaptation because the gene or genes are exposed to selection in the sex carrying only a single X‐chromosome. The present study seeks to understand which of these alternatives more likely explains the rapid photoperiodic adaptation in European Colorado potato beetles Leptinotarsa decemlineata Say. Diapause induction is assessed in beetles from a northern and a southern population, as well as from reciprocal hybrid crosses between the northern and southern population, when reared at an intermediate length photoperiod. The crosses within population display the expected responses, with the northern and southern populations showing high and low diapause propensity, respectively. The hybrids show intermediate responses in all studied traits. No clear difference in the responses in hybrids depending on the latitudinal origin of their father or mother is detected, even though partial paternal line dominance is seen in the responses of male beetles in one hybrid cross. These results therefore indicate that, in L. decemlineata, photoperiodic diapause induction is strongly heritable, and has an additive polygenic autosomal background.     

烟蚜茧蜂滞育诱导的温光周期反应

烟蚜茧蜂Aphidius gifuensis Ashmead是可持续防控蚜虫的优良内寄生蜂,在害虫生防中具有重要作用,研究其滞育对探索发育调控机制、延长产品货架期、提高防治效果意义重大。本文采用梯度变温法和光周期反应曲线法,系统研究了温度和光周期对烟蚜茧蜂滞育诱导的影响,研究结果表明:烟蚜茧蜂以老熟幼虫滞育,滞育类型属冬滞育型。低温、短光照是诱导烟蚜茧蜂滞育的主要环境因子,二者相互配合能诱导更多个体滞育。短光照(L∶D=8∶16)条件下,温度低于12℃可诱导烟蚜茧蜂进入滞育,8℃时滞育率可达54.35%。长光照(L∶D=14∶10)下,高温不能诱导烟蚜茧蜂滞育,低温下的滞育率较低,仅为1.79%。低温(10℃)下,短光照(8 h)可诱导50.70%的高滞育率,光照为14 h和6 h其滞育率均显著下降。25℃时,不同光照下滞育率均为0,光周期作用不显著。综合而言,温度和光周期均能显著影响烟蚜茧蜂的滞育,温度较光周期的滞育诱导效能更显著,二者互作配合能极显著的诱导烟蚜茧蜂进入滞育态。     

Geographic variation in photoperiodic diapause induction and diapause intensity in Sericinus montelus (Lepidoptera: Papilionidae)

Abstract Due to the risk of extinction and ornamental value of the swallowtail butterfly, Sericinus montelus Gray (Lepidoptera: Papilionidae) in China, knowledge about local adaptations is important for the conservation and economical utilization of the species. In the present study, photoperiodic diapause induction and diapause intensity of S. montelus populations from Jiamusi (46°37′N), Beijing (40°15′N), Zibo (36°48′N), Fangxian (32°36′N), Wuhan (30°33′N) and Huaihua (27°33′N) were characterized at 25°C. Logistic regression analysis revealed a significant population × hours of light interaction, confirming that photoperiodic responses varied among populations. The critical photoperiod was positively correlated with latitude and increased toward the north at a rate of about 1 h for each 6.67 degrees of latitude. Survival analyses indicated that survival time of diapausing pupae before adult eclosion differed significantly among populations at 25°C and 16 : 8 L : D h. The mean duration of pupal diapause was also positively correlated with latitude. Our study reveals geographic variation in the critical photoperiod for diapause induction and in diapause intensity of S. montelus. These results provide useful information for our general understanding about seasonal adaptation in insects and may also be used to predict how geographic populations respond to climate warming.     

The influence of temperature on the photoperiodic regulation of diapause in saturniids

Contrary to previous observations, induction of diapause in A. pernyi can be modified by high temperatures. Termination of diapause can also be achieved in the majority of unchilled pupae at 32°C and under short-day conditions. A. polyphemus is more sensitive to slight changes in rearing temperatures; short days and temperatures over 29°C completely prevent diapause induction and also promote its termination. Those temperatures most effective in inducing diapause tend to maintain it, whereas temperatures most effective in preventing its induction tend to terminate the dormancy in both the saturniids.     

Adaptive latitudinal cline of photoperiodic diapause induction in the parasitoid Nasonia vitripennis in Europe

Living in seasonally changing environments requires adaptation to seasonal cycles. Many insects use the change in day length as a reliable cue for upcoming winter and respond to shortened photoperiod through diapause. In this study, we report the clinal variation in photoperiodic diapause induction in populations of the parasitoid wasp Nasonia vitripennis collected along a latitudinal gradient in Europe. In this species, diapause occurs in the larval stage and is maternally induced. Adult Nasonia females were exposed to different photoperiodic cycles and lifetime production of diapausing offspring was scored. Females switched to the production of diapausing offspring after exposure to a threshold number of photoperiodic cycles. A latitudinal cline was found in the proportion of diapausing offspring, the switch point for diapause induction measured as the maternal age at which the female starts to produce diapausing larvae, and the critical photoperiod for diapause induction. Populations at northern latitudes show an earlier switch point, higher proportions of diapausing individuals and longer critical photoperiods. Since the photoperiodic response was measured under the same laboratory conditions, the observed differences between populations most likely reflect genetic differences in sensitivity to photoperiodic cues, resulting from local adaptation to environmental cycles. The observed variability in diapause response combined with the availability of genomic tools for N. vitripennis represent a good opportunity to further investigate the genetic basis of this adaptive trait.     

Inheritance of photoperiodic induction of larval diapause in the Asian corn borer Ostrinia furnacalis

The Asian corn borer Ostrinia furnacalis (Guenée) enters facultative diapause as fully‐developed larvae in response to short‐day conditions. As a consequence of geographical variation in photoperiodic response, moths from Nanchang (28°46′N, 115°50′E) enter diapause in response to short day‐lengths (D strain), even at the high temperatures whereas moths from Ledong (18°47′N, 108°89′E) exhibit almost no diapause under the same conditions (N strain). In the present study, crosses between the two strains are used to evaluate the inheritance of diapause under different photoperiods at temperatures of 22, 25 and 28 °C. The moths, both reciprocal crosses and backcrosses, show a clear long‐day response, similar to that of the D strain, suggesting that the photoperiodic response controlling diapause in this moth is heritable. However, the critical day‐length for induction of diapause is shorter in hybrids than in the D strain. The N strain also shows a short‐day photoperiodic response at the lower temperature of 22 °C, indicating that the N strain still has the capacity to enter a photoperiodically‐induced diapause, depending on the rearing temperature. The incidence of diapause in all crosses is highest with D strain fathers or grandfathers and lowest with N strain fathers or grandfathers, indicating that the male parent has significantly more influence on the incidence of diapause of subsequent progeny than the female. The results obtained from all crosses under LD 12 : 12 h or LD 13 : 11 h photocycles at 25 °C show that inheritance of diapause in O. furnacalis does not fit an additive hypothesis and that the capacity for diapause is transmitted genetically in the manner of incomplete dominance.     

Sexual difference in the photoperiodic induction of pupal diapause in the flesh fly Sarcophaga similis

The flesh fly Sarcophaga similis enters pupal diapause in response to short days, but averts diapause under long days. This species shows a sexual difference in the photoperiodic induction of diapause, with females having shorter critical daylength than males. Here, we proposed two hypotheses to explain this sexual difference. First, we proposed a sexual difference in the qualitative evaluation of photoperiods. This hypothesis assumes under the external coincidence model that although the photoinducible phase of both sexes locates at late scotophase, in males, it locates at a slightly earlier phase. However, the results of night interruption experiments clearly ruled out this hypothesis. Because we verified that S. similis evaluated photoperiods quantitatively, we next proposed a sexual difference in the quantitative evaluation of photoperiods. This hypothesis incorporates concepts of a hypothetical substance accumulation that shows a diapause‐inducing effect and an internal threshold that serves as a reference to determine the diapause/nondiapause developmental program. In long‐day exposure experiments and night interruption experiments, females consistently showed a lower incidence of diapause than males. Thus, the present study data satisfactorily meet the second hypothesis, that is a sexual difference in the quantitative evaluation of photoperiods exists in S. similis.     

Effect of diet on the photoperiodic induction of diapause in three species of predatory mite,Amblyseius potentillae,A. cucumeris andTyphlodromus pyri

The predatory mitesAmblyseius potentillae, A. cucumeris andTyphlodromus pyri entered diapause in response to a short-day photoperiodic regime, when they were reared on pollen of the ice plant,Dorotheanthus bellidiformis. With pollen of the broad bean,Vicia faba, as food, however, diapause was virtually absent inA. potentillae andA. cucumeris under the same short-day regime, but full diapause was found inT. pyri. The importance of carotenoids for the photoperiodic response in these predatory mites is discussed.     

Quantitative trait loci associated with photoperiodic response and stage of diapause in the pitcher-plant mosquito, Wyeomyia smithii

A wide variety of temperate animals rely on length of day (photoperiodism) to anticipate and prepare for changing seasons by regulating the timing of development, reproduction, dormancy, and migration. Although the molecular basis of circadian rhythms regulating daily activities is well defined, the molecular basis for the photoperiodic regulation of seasonal activities is largely unknown. We use geographic variation in the photoperiodic control of diapause in the pitcher-plant mosquito Wyeomyia smithii to create the first QTL map of photoperiodism in any animal. For critical photoperiod (CPP), we detect QTL that are unique, a QTL that is sex linked, QTL that overlap with QTL for stage of diapause (SOD), and a QTL that interacts epistatically with the circadian rhythm gene, timeless. Results presented here confirm earlier studies concluding that CPP is under directional selection over the climatic gradient of North America and that the evolution of CPP is genetically correlated with SOD. Despite epistasis between timeless and a QTL for CPP, timeless is not located within any detectable QTL, indicating that it plays an ancillary role in the evolution of photoperiodism in W. smithii. Finally, we highlight one region of the genome that includes loci contributing to CPP, SOD, and hormonal regulation of development.     

Circadian component influences the photoperiodic induction of diapause in a drosophilid fly, Chymomyza costata

The last-instar larvae of a drosophilid fly, Chymomyza costata enter diapause in response to the dark-phases longer than 9 h (Yoshida, T., Kimura, M.T., 1995. The photoperiodic clock in Chymomyza costata. Journal of Insect Physiology 41, 217-222). In order to switch the developmental programming of the sensitive larvae from continuous development to diapause, after they were transferred from the short (8 h) to the long (14 h) dark-phase, significantly less time (1-2 days) was required when the dark-phase was abruptly and asymmetrically extended into the evening, than when it was extended symmetrically into both morning and evening (2-3 days), or asymmetrically into the morning hours (4-6 days). Diapause was also induced in 40-70% of sensitive larvae that were reared under the gradually shortening light-phase (from 16 h to 2 h, by 1 h in each cycle), despite that the dark-phase remained constant and short (8 h). Larvae developed continuously, however, when reared under the gradually extending light-phase (from 16 h to 24 h) and a constantly short dark-phase. We interpret such results, with the help of the two-oscillator model of circadian rhythmicity (Pittendrigh, C.S., Daan, S., 1976. A functional analysis of circadian pacemakers in nocturnal rodents. V. Pacemaker structure: A clock for all seasons. Journal of Comparative Physiology A 106, 333-355), as indicating that two mutually coupled oscillators (evening and morning) differing in their entrainability may participate in measuring of the dark-phase duration. The levels of dopamine (DA) and serotonin (5-HT) in the larval CNS transiently increased (by up to 20%) after the dusk, while no apparent change was observed during the dawn. The dusk-related increase was observed also after the asymmetric extension of the dark-phase into evening, while the asymmetric extension into morning had no effect on the levels of the DA and 5-HT.     

Functional involvement of carotenoids in photoperiodic induction of diapause in the spider mite, Tetranychus urticae

ABSTRACT. Using pigment mutants in which the uptake and oxidative metabolism of β-carotene is disturbed, it could be shown that carotenoid pigments are functionally involved in the photoperiodic reaction in the spider mite, Tetranychus urticae Koch (Acari; Prostigmata). Diapause responses appeared to be lowered in four albino mutants in comparison with the wild-type strains from which they originated. Back-crossing of the albino mutants to wild-type for ten generations did not restore the capability to diapause. Selection for diapause for six generations also proved unsuccessful in increasing the diapause response of the albino strains. On the other hand, albino mites coming from hybrid (phenotypically wild-type) mothers all diapaused normally. Apparently a maternal effect is responsible for the complete induction of diapause in albino mites. It is supposed that minimal amounts of carotenoids of maternal origin suffice in the embryo for the formation of a photopigment concerned in the photoperiodic induction of diapause. In albino mites the normal transmission of carotenoids via the egg is probably blocked. This transmission of pigment seems to be restored when the albinos originate from hybrid mothers, which possess the wild pigmentation.     

光周期和温度对亚洲玉米螟滞育诱导的影响

亚洲玉米螟Ostrinia furnacalis (Guenée)属兼性滞育昆虫, 其滞育特性与种群利用适生境的最大化和季节性活动密切相关。解析季节性因素如光周期和温度对其滞育的诱导作用可为预测种群发生动态提供科学依据。本实验在HPS 500型和HPG-320H型自动控制环境气候箱中, 测定了RH 80%下温度20℃, 27℃和30℃与11个光周期组合对吉林农安（NA）、 河北衡水（HS）、 广东惠州（HZ）和海南海口（HK）等4个地理种群的滞育诱导作用。结果表明： 光周期、 温度及其交互作用均对亚洲玉米螟滞育诱导具有重要影响, 其中光周期在滞育诱导中起主导作用。在20℃条件下, 其光周期反应曲线属典型的长日照反应型, 临界光周期随种群分布的地理纬度降低而缩短, 4个地理种群NA, HS, HZ和HK的临界日昼长依次为14 h 3 min, 13 h 59 min, 13 h 32 min和13 h 7 min, 最有效的滞育诱导光周期是日昼长12 h。另一方面, 随种群分布纬度升高, 其对光周期诱导滞育的敏感性降低。温度为27℃时, 其光周期反应曲线为短日照 长日照反应型, 各种群有两个临界光周期, 临界日昼长依次为12 h 50 min和13 h 32 min, 11 h 35 min和13 h 8 min, 12 h 58 min和13 h 1 min, 以及11 h 50 min和12 h 26 min, 且最有效的滞育诱导光周期范围的滞育率明显低于20℃。一定温度范围内（20℃～27℃）, 随温度升高, 临界光周期缩短; 温度达到30℃时则滞育显著被抑制, 滞育率仅为4.3%或更低。这些结果说明温度对亚洲玉米螟滞育的光周期诱导具有很强的补偿作用。因此, 在自然界亚洲玉米螟的滞育属具有温度补偿作用的长日照反应型昆虫, 临界光周期随地理纬度北移而增长; 种群滞育的短日照 长日照反应型特性可能是产生局部世代种群的重要内因。     

Existence of a light-sensitive phase in the photoperiodic termination of diapause inPieris brassicae L. (Insecta:Lepidoptera) and comparison with diapause induction

Summary Pupal diapause ofPieris brassicae can be terminated experimentally by the sole action of photoperiod. Curves gave evidence of similar effect of photoperiod within a broad range of regimes in both diapause induction and termination. However, they showed opposite responses to ultra-short and ultra-long days and to continuous light and darkness. In diapause termination, the critical daylength is longer than in diapause induction by about 1.20 h.Results of night interruption experiments (asymmetrical skeleton photoperiods) provided the first reliable evidence of the involvement of a particular light-sensitive phase in photoperiodic diapause termination. A light pulse delivered at this moment elicited a complete long-day effect (i.e. diapause termination). Only one single point of long-day effect (lying in the early night) was disclosed in diapause termination whereas two points (A and B) characterize diapause induction in this species. Results of experimental designs where the period of the photoperiodic cycles differed from 24 h indicated that photoperiodic clock likely makes a nightlength measurement in both diapause induction and termination. This is discussed in relation to the formal properties of the clock, especially those derived from the time distribution of points of long-day effect.     

Interactive effects of photoperiod and temperature on diapause induction and termination in the yellow-spotted longicorn beetle, Psacothea hilaris

Abstract. The interactive effects of temperature (20 °C or 25 °C) and photoperiod (LD 12 : 12 h or LD 15 : 9 h) on diapause induction and termination are investigated in the west‐Japan type yellow‐spotted longicorn beetle, Psacothea hilaris (Pascoe) (Coleoptera: Cerambycidae). Larval diapause of P. hilaris is induced under three diapause‐inducing conditions (20 °C–SD, 20 °C–LD and 25 °C–SD), and the diapause larvae are transferred to one of four conditions (20 °C–SD, 20 °C–LD, 25 °C–SD or 25 °C–LD) for observation of pupation, which indicates termination of diapause. The intensity of diapause induced under the three conditions increases in the order 20 °C–SD < 25 °C–SD < 20 °C–LD, when assessed by the time course of pupation after the transfer. On the other hand, the effectiveness of the temperature–photoperiod combinations to terminate diapause is in the order 25 °C–SD (ineffective) < < 20 °C–LD < 25 °C–LD < 20 °C–SD. Among the temperatures (5, 10, 15 and 20 °C) examined, 15 °C is the most effective in terminating diapause under the short day; diapause in most larvae appears to have been completed in 15 days.