Rhythmicity in life events of an aphidophagous ladybird beetle, Cheilomenes sexmaculata

Abstract:  The present laboratory experiments have been carried out to investigate rhythms in various life events, viz. mating, oviposition, hatching, moulting, pupation and eclosion, of an aphidophagous ladybird beetle, Cheilomenes sexmaculata under laboratory conditions. Incidences of mating and eclosion occurred mostly (66% and 73% respectively) in photophase. While oviposition, hatching, moulting and pupation occurred during scotophase with the peaks of the former two distributed between time intervals 12:00–15:00 h and 21:00–00:00 h respectively. Confinement of life events that are associated with vulnerable stages in scotophase might be an adaptation to prevent their exposure to natural enemies.     

Endogenously entrained life events of Parthenium beetle,Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae)

Biological rhythm is ubiquitous in all living organisms and is known to govern physiology, behavior, and population of insects. Though these rhythms are generated endogenously, they are entrained by environment. This experiment aims to evaluate the diel rhythms of mating, hatching and oviposition, and the influence of parental mating rhythm on their progeny. Peak of mating and oviposition incidences were recorded during later part of the photophase, which might be ascribed to the foraging rhythm during the day. However, maximum hatching was recorded during the scotophase which appears to be a survival strategy. Mating, oviposition, and hatching rhythms did not change on consecutive days and were thus probably endogenous in nature. It was also observed that the rhythm of parental mating had profound effect on their offspring fitness in terms of development and survival.     

Ovipositional Rhythmicity in Ladybirds (Coleoptera: Coccinellidae): A Laboratory Study

Complete and diel ovipositional rhythms have been observed in three aphidophagous ladybirds (Coleoptera: Coccinellidae): Coccinella septempunctata Linnaeus, Coccinella transversalis Fabricius and Propylea dissecta (Mulsant) for the first time. The complete ovipositional rhythm could be described in terms of a polynomial curve and daily fluctuations in all three species. In the diel cycle, all three ladybird species oviposited significantly in the scotophase. C. septempunctata females preferred to oviposit at the end of scotophase in the early morning hours (0300-0700), P. dissecta laid most eggs in the middle of scotophase during the night (2100-2300), and C. transversalis laid most at the beginning of the scotophase at dusk (1700-1900). While the diel ovipositional rhythm of C. septempunctata and P. dissecta did not differ between days, that of C. transversalis changed dramatically; there was a single peak on the first and second day of observation, and four oviposition peaks on the fifth day with the peaks being situated in the two hours preceding and succeeding the onset and end of the scotophase. Diel rhythms of C. septempunctata and P. dissecta appear to be endogenous in nature while that of C. transversalis is partly modified by exogenous factors.     

Daily rhythms in the sorghum shootfly, Atherigona soccata: oviposition, egg-hatch and adult eclosion

ABSTRACT. Daily rhythms controlling oviposition, egg-hatching and adult eclosion in the sorghum shootfly, Atherigona soccata Rondani, were investigated. Eggs were laid only during the photophase of a LD 12:12 cycle, in two peaks. Under continuous light, this oviposition was considerably attenuated but not made immediately arrhythmic. Egg-hatching and adult eclosion both commenced just before dawn. Some feature of the scotophase during or immediately after black-head formation apparently acts as a signal for hatching. Eclosion was controlled by light but its timing in the field was modified by temperature. The last 2–3 days of the pupal period constituted the most sensitive stage, and light signals received during this period determined the time of eclosion. Ecological advantages of these rhythms to the shootfly are discussed.     

Does the difference in the timing of eclosion of the fruit fly Drosophila melanogaster reflect differences in the circadian organization?

The eclosion rhythm of a laboratory population of Drosophila melanogaster was studied under 12h light, 12h dark (LD 12:12) cycles. Although most of the flies were found to eclose just after “lights on” in LD 12:12, termed within gate (WG) flies, a few flies were found to eclose nearly 10h after peak eclosion, termed outside gate (OG) flies. The circadian parameters of the clocks controlling oviposition rhythms in the WG and the OG flies were estimated to understand the cause of such differences in the timing of eclosion. The distribution of the fraction of individual flies exhibiting single, multiple, and no significant period in the WG flies was significantly different from distribution in the OG flies. Compared to the WG flies, more OG flies were found to exhibit oviposition rhythm with multiple periodicity, whereas more WG flies exhibited an oviposition rhythm with a single significant period. The fraction of flies with arrhythmic oviposition was similar in both the WG and the OG flies. Free-running period τ in constant darkness (DD) and the phase angle difference ψ in LD 12:12 for the oviposition rhythm of WG and OG flies were significantly different. These results suggest that the differences in the time of eclosion between the flies eclosing within the gate and outside the gate of eclosion are probably due to differences in the circadian system controlling eclosion, which is reflected by the differences in their oviposition rhythm. (Chronobiology International, 18(4), 601-612, 2001)     

Mating behaviour in Oncopeltus fasciatus: circadian rhythms of coupling, copulation duration and 'rocking' behaviour

ABSTRACT. Circadian rhythms are demonstrated in initiation and duration of copulation, and in 'rocking' by females during mating in the large milkweed bug, Oncopeltus fasciatus. In constant light or darkness there were no more than two or three recognizable cycles of any of these rhythms. In addition, light directly stimulated copulatory attempts, but did not influence their chance of success. Copulations were generally shorter during the early-mid photophase and longer during the late photophase in LD 16:8, while initiations of copulation were fewest during the scotophase. The males were mainly responsible for these rhythms. It is suggested that the diurnal rhythm in copulation duration probably evolved as a consequence of the rhythms of flight activity and/or oviposition. Sperm from the late photophase matings typically displaced 90–100% of sperm from prior matings, while sperm from the shorter early photophase matings typically displaced less prior sperm. Peak rocking activity during mating occurred from 6 to 8 h after lights-on in LD 16:8. Little rocking occurred during the late photophase, when the greatest percent of pairs are in copula. Feeding and drinking inhibited rocking activity, but the feeding rhythm did not drive the rocking rhythm. Rocking appears not to function in promoting termination of mating, positioning of the aedeagus, nor to mediate mechanical stimulation of egg production. Its function remains unknown.     

Multi-Oscillatory Control of Eclosion and Oviposition Rhythms in Drosophila melanogaster: Evidence from Limits of Entrainment Studies

The eclosion and oviposition rhythms of flies from a population of Drosophila melanogaster maintained under constant conditions of the laboratory were assayed under constant light (LL), constant darkness (DD), and light/dark (LD) cycles of 10:10 h (T20), 12:12 h (T24), and 14:14 h (T28). The mean (±95% confidence interval; CI) free-running period (τ) of the oviposition rhythm was 26.34 ± 1.04 h and 24.50 ± 1.77 h in DD and LL, respectively. The eclosion rhythm showed a τ of 23.33 ± 0.63 h (mean ± 95% CI) in DD, and eclosion was not rhythmic in LL. The τ of the oviposition rhythm in DD was significantly greater than that of the eclosion rhythm. The eclosion rhythm of all 10 replicate vials entrained to the three periodic light regimes, T20, T24, and T28, whereas the oviposition rhythm of only about 24 and 41% of the individuals entrained to T20 and T24 regimes, respectively, while about 74% of the individuals assayed in T28 regimes showed entrainment. Our results thus clearly indicate that the τ and the limits of entrainment of eclosion rhythm are different from those of the oviposition rhythm, and hence this reinforces the view that separate oscillators may regulate these two rhythms in D. melanogaster.     

Diel changes in the presence and physiological actions of octopamine in the female sex-pheromone glands of heliothine moths

Recent evidence suggests that the biogenic monoamine octopamine (OA) may be involved in the regulation of female sex-pheromone production in Lepidoptera. A radioenzymatic assay coupled with high performance liquid chromatography revealed the presence of OA in the innervated sex-pheromone gland of the corn earworm moth Helicoverpa (Heliothis) zea. Significantly more OA was found in glands just before the onset of scotophase (ca 320 fmol/gland), compared to levels at mid-photophase or just after the onset of scotophase (ca 160 fmol/gland).

Exogenous OA had several actions on pheromone production. H. zea virgin females normally do not produce pheromone during the photophase, but highly significant levels of pheromone were induced by injection of OA into intact, day-2 photophase females. Importantly, this effect was absent in older females that showed increased levels of flight and oviposition activity. A second action of OA was revealed in isolated abdomen preparations from day-2 H. virescens females. Exogenous OA stimulated highly significant increases in pheromone production if abdomens were treated at the onset of scotophase, but not if they were treated in photophase. This critical period for OA action in these reduced preparations coincided with the time when peak levels of OA were present in the pheromone gland tissue. OA is therefore sufficient to induce pheromone production, but its actions in these short-lived insects depend on factor such as age and photoperiod. Diel fluctuations in OA levels in the pheromone gland, together with the observed phermonotropic actions of this amine, support the hypothesis that OA is involved in the regulation of pheromone production in these insects.     

Latitudinal variation in oviposition rhythm of Drosophila ananassae strains originating from the equator to subtropics

Parameters of oviposition rhythm of Drosophila ananassae strains originating from the equator, 0°N to 22.29°N were variable and latitude dependent. Phase angle difference (Ψ), amplitude of rhythm (R) and the percent oviposition in photophase (POP) were determined in LD 12:12 cycles. Although the R did not vary, the Ψ and POP varied by ∼5 h and 60, respectively. Ψ was positively correlated while the POP was negatively correlated with latitude. Transfers from LD 12:12 cycles to constant darkness initiated free-running rhythms in all strains. Although the R did not vary, the τ varied by ∼3.5 h which was positively correlated with latitude.     

Thermoregulatory and endocrine responses to light pulses in short-day acclimated social voles (Microtus socialis)

In mammals, nocturnal light pulses (NLP) have been demonstrated to affect physiology and behavior. However, the impact of NLP as a stressor has been less broadly examined. The purpose of this study was to examine the effect of NLP (three 15 min 450 lux light pulses) during each scotophase on both thermoregulation and endocrine stress responses under short-day (SD; 8L:16D) acclimation. Voles were acclimated to either SD (SD voles) or SD+NLP (NLP voles). Resistance to cold was estimated by measurements of body temperature (T_b) during cold exposure (5°C). Daily rhythms of energy expenditure (calculated from oxygen consumption), urine production, and urinary adrenaline and serum cortisol levels were measured. T_b values of SD voles were generally unaffected by the cold stimulus, whereas in NLP voles, resistance to cold was markedly lowered. While SD- and NLP voles showed similar ultradian characteristics in energy expenditure with a period of 3.5 h, mean energy expenditure levels were lowest for voles exposed to NLP-treatment. In SD voles, but not in NLP voles, urine production rates showed clear time variations and were consistently highest for SD voles, with significant differences during the scotophase. Both mean total urinary adrenaline and serum cortisol levels were significantly elevated in NLP-treated voles compared with the control group. Taken together, the results suggest that NLP negatively affects winter acclimatization of thermoregulatory mechanisms of M. socialis, probably by mimicking summer acclimatization, and consequently the thermoregulatory mechanisms respond inappropriately to ambient conditions. One important finding of this study is that NLP may act as a stressor and correspondingly impose a major threat to the physiological homeostasis of M. socialis, such that over-winter survival might be compromised.     

CRISPR/Cas9-based knockout reveals that the clock gene timeless is indispensable for regulating circadian behavioral rhythms in Bombyx mori

Circadian rhythms, which are ubiquitous and adaptive, occur across all species, from microbes to humans, in which they organize and modify behavior and physiology. timeless (tim) is a canonical clock gene. The core composition of the Drosophila melanogaster endogenous circadian clock has been extensively investigated; however, in lepidopteran insects, including Bombyx mori, the mechanism is complicated and little is known regarding the participation of tim in the negative feedback loop responsible for behavioral activities. To arrive at a comprehensive understanding of the role of tim in the B. mori endogenous circadian clock, we exploited the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 gene editing system. We attempted to elucidate the functions of tim in the circadian clock of B. mori using Bmtim mutants. The knockouts affected two circadian behavioral activities: adult emergence and embryo hatching rhythms. Quantitative real-time polymerase chain reaction results confirmed that tim-knockouts induced relative reductions in the expression levels, and thereby the oscillation amplitudes, of Bmper and Bmclk messenger RNAs during both the photophase and scotophase. Additionally, the daily rhythmic expression of Bmdbt was upregulated in the photophase and downregulated in the scotophase in a tim-knockout. Our study reveals that tim is integral to the B. mori circadian clock and may be involved in regulating eclosion and hatching rhythms.     

Effect of light intensity on the oviposition rhythm of the altitudinal strains of Drosophila ananassae

The sensitivity of the circadian photoreceptors mediating entrainment of the eclosion rhythm and phase shifts of oviposition rhythm of the high altitude (HA) strain of Drosophila ananassae originating from Badrinath (5123 m above sea level) in the Himalayas was compared with the low altitude (LA) strain from Firozpur (179 m above sea level). Reduced photic sensitivity of the HA strain is regarded as the result of natural selection, which led to the weakening of the coupling mechanism between the circadian pacemaker and light at the high altitude of origin. The present study was designed to determine whether or not the photic entrainment of the oviposition rhythm of the HA strain of D. ananassae is also altered by the high altitude of its origin, and the results are compared with those of the LA strain. The effects of light intensity on the phase angle difference (Ψ), degree of rhythmicity (R), the percent oviposition in photophase, the threshold light intensity (i.e., the intensity at which stable entrainment occurred), and the saturation light intensity (i.e., the intensity beyond which the values of Ψ or amplitude of rhythm remained unaltered) were determined. Entrainment was studied in light-dark cycles in which the light intensity of 12 h of photophase varied from 1 to 1000 lux, and complete darkness prevailed in all scotophases. The oviposition rhythm of the HA strain was arrhythmic from 1 to 90 lux, weakly rhythmic at 95 lux, but rhythmic at or above 100 lux, while that of the LA strain was weakly rhythmic at 1 lux but rhythmic at or above 2 lux. Oviposition of the HA strain occurred mostly in the photophase, while that of the LA strain occurred in the scotophase; as a result, the oviposition medians of the HA strain were around the subjective forenoons while those of the LA strain were around the subjective evenings. The percent of oviposition in photophase increased from 68 to 98 in the HA strain and from 5 to 33 in the LA strain as light intensity increased from 1 to 1000 lux. In the HA strain, the Ψ values were significantly less and values of R and percent oviposition in photophase were significantly more than those of the LA strain at each level of light intensity. Threshold and saturation intensities for Ψ were 100 and 700 lux, respectively, for the HA strain, but just 2 and 45 lux, respectively, for the LA strain. The saturation intensity for R was 650 and 700 lux for the HA and LA strains, respectively. These results extend the confirmation that the reduced photic sensitivity of the HA strain might have been acquired through natural selection in response to environmental conditions at the high altitude of its origin.     

Effects of temperature on development and growth in the tick,Haemaphysalis longicornis

As a part of ecological studies onHaemaphysalis longicornis, the effects of controlled temperatures (12, 15, 20, 25 and 30°C; 100% RH) on development and growth of the tick were investigated and the critical low temperature for each stage in the life cycle was estimated. As the temperature became low, the periods of preoviposition, oviposition, egg hatching (incubation) and moulting were prolonged. At 12°C, however, oviposition, egg hatching and moulting of the larva and nymph did not occur. The critical low temperatures for oviposition, egg hatching (developmental zero) and larval and nymphal moulting which were calculated theoretically from the regression equations, were 11.1, 12.2, 10.2 and 11.8°C, respectively. The temperature also affected the egg productivity and hatch-ratio. The number of deposited eggs per mg of body weight decreased markedly at 15°C, and the hatch-ratio was lowered with dropped temperatures.     

大螟成虫性信息素生物合成和释放及求偶和交配行为的昼夜节律

【目的】探索大螟Sesamia inferens性信息素顺11-十六碳烯乙酸酯(Z11-16∶Ac)和顺11-十六碳烯醇(Z11-16∶OH)的合成和释放及求偶和交配行为的昼夜节律,及其与田间性信息素诱捕的关系。【方法】通过溶剂浸提和固相微萃取(solid phase microextraction, SPME)分析大螟雌蛾性信息素Z11-16∶Ac和Z11--16∶OH的滴度,结合行为观测和多地田间实时性信息素诱捕数据,调查大螟性信息素的生物合成、释放及求偶和交配行为的昼夜节律。【结果】大螟雌蛾腺体内性信息素Z11-16∶Ac和Z11-16∶OH含量可检测到的时间始于暗期前1 h,暗期后4 h快速增加,暗期8 h为第1次高峰,但光期1h又一次高峰,光期5 h还可以被显著检测到。分泌至腺体外的性信息素化合物可检测到的时间始于暗期后6 h,高峰期在暗期后10 h,光期后1 h性信息素Z11-16∶Ac滴度达到96.9±20.9 ng/雌。采用溶剂浸提法获得的Z11-16∶Ac和Z11-16∶OH的比例在暗期平均为2.8±1.9,在光期平均为2.5±0.9,统计上二者没有显著差异,而SPME法获得的Z11-16∶Ac和Z11-16∶OH的比例在暗期平均为8.5±1.2,在光期平均为5.7±0.6,统计上二者差异显著。产卵器伸出时间发生在暗期6-8 h,产卵器伸出持续时间平均为80.8±4.4 min。大螟的交配发生在暗期4-10 h,交配持续时间平均为83.4±5.0 min。广东、四川、浙江、江苏四省性诱自动计数的田间每日每小时实时计数数据显示,越冬代诱蛾比较集中,之后的世代则比较分散,田间雄蛾的性诱昼夜节律受地理环境、季节和世代等因子的影响。【结论】本研究发现大螟交配和性信息素释放的昼夜节律在时间上不一致,交配时间在暗期较早时段。雌蛾性信息素有效的释放时间范围比雄蛾对性信息素反应的要小。产卵器伸展与雌蛾性信息素化合物的释放速率加快和扩散 范围有关。     

The circadian system of Trypanosoma cruzi-infected mice

The effects of Chagas disease on the mammalian circadian system were studied in Trypanosoma cruzi-infected C57-Bl6J mice. Animals were inoculated with CAI or RA strains of T. cruzi or vehicle, parasitism confirmed by blood specimen visualization and locomotor activity rhythms analyzed by wheel-running recording. RA-strain infected mice exhibited significantly decreased amplitude of circadian rhythms, both under light-dark and constant dark conditions, probably due to motor deficiencies. CAI-treated animals showed normal locomotor activity rhythms. However, in these mice, reentrainment to a 6h phase shift of the LD cycle took significantly longer than controls, and application of 15min light pulses in DD produced smaller phase delays of the rhythms. All groups exhibited light-induced Fos expression in the suprachiasmatic nuclei. We conclude that the main effect of T. cruzi infection on the circadian system is an impairment of the motor output from the clock toward controlled rhythms, together with an effect on circadian visual sensitivity.     

松树蜂的产卵行为

【目的】研究松树蜂Sirex noctilio的产卵行为,明确其产卵能力,为评估其繁殖潜力和危害能力提供基础数据。【方法】于黑龙江省大庆市杜尔伯特蒙古族自治县新店林场采集被松树蜂危害的寄主樟子松Pinus sylvestris var.mongolica木段上获得虫源。在室内条件下观察和分析松树蜂产卵的行为过程及规律。解剖松树蜂在樟子松木段上的产卵孔,并观察其结构特征。【结果】松树蜂羽化时即性成熟,能够马上进行交配和产卵。松树蜂雌成虫一次完整的产卵过程主要分为4个动作:树皮钻孔、木质部钻刺、产卵(注入有毒黏液和共生真菌Amylosereum areolatum)和产卵器拔出。产卵时间在360～540 s之间的产卵频数最多,占产卵总频数的41.40%;产卵过程中木质部钻刺用时最长,至少占整个产卵过程用时的90%。松树蜂雌成虫在一个产卵孔处会进行1～4次产卵,产卵时间和产卵次数呈显著正相关,当产卵时间t<360 s时,进行了1次产卵;当360 s≤t<540 s时,进行了2次产卵;当540 s≤t<780 s时,进行了3次产卵;当t≥780 s时,进行了4次或更多次产卵。松树蜂在一个产卵孔处进行1, 2, 3和4次产卵的比例分别为21.66%, 41.40%, 27.39%和9.55%。【结论】松树蜂雌成虫在一个产卵孔处的产卵时间和产卵次数呈正相关。利用产卵时间和产卵次数的关系,在只调查产卵时间的情况下,可以推断产卵次数。松树蜂在一个产卵孔处产卵的次数多,对寄主樟子松危害大。     

Oviposition by Mamestra brassicae (L.) (Lep., Noctuidae) in relation to age, time of day and host plant

The age at which females begin to lay, the daily pattern of oviposition, the influence of host-plant material on egg-laying as well as the host preference of Mamestra brassicae L. (Lep., Noctuidae) were investigated under laboratory conditions. The females began to oviposit during the third, fourth and fifth scotophase after emergence. A great variability in daily female fecundity was observed. The highest level of oviposition occurred during the fifth day. Females oviposited during the whole scotophase, but maximal oviposition occurred during the second hour. The females without host-plant material laid fewer eggs than females with host-plant material (cabbage leaves Brassica oleracea var. capitata ). In two-choice tests, the females preferred to oviposit on cabbage rather than chrysanthemum, but there was no difference in the mean number of eggs laid on cabbage and tomato. There were significantly greater mean numbers of total eggs deposited on tomato than on chrysanthemum.     

旅游干扰下水质对大鲵繁殖行为与繁殖力的影响

通过控制大鲵仿生态繁育池进水量模拟旅游干扰下的水质溶解氧特征,采用红外数字监控系统研究大鲵繁殖行为(产卵与护卵)及繁殖力(相对产卵量、受精率与孵化率)特点,分析它们与水质的关系,探讨旅游干扰导致的水质变化对大鲵繁殖行为及繁殖力的影响。结果表明: 与对照组相比,旅游干扰下大鲵的产卵行为与繁殖力未受到显著影响,但雄鲵护卵行为中的扇尾与搅动时间显著延长,以提高水中溶解氧浓度,满足大鲵胚胎发育需求;此外,旅游干扰下受精卵的孵化时间显著延长,但孵化率未受到显著影响。雄鲵护卵行为变化与受精卵孵化时间延长可能是大鲵对旅游干扰导致的水质变化的一种主动响应。     

Field and laboratory studies on the timing of oviposition and hatching of the western black-legged tick, Ixodes pacificus (Acari: Ixodidae)

The timing of oviposition and hatching of Ixodes pacificus was investigated in the field and at constant temperatures in the laboratory. Replete females held at temperatures between 9 and 29°C began depositing eggs a mean of 9–70 days after drop off. Egg masses held between 12 and 25°C commenced hatching 25–178 days after the onset of oviposition. Eggs held at 9 or 29°C did not hatch. The lower temperature thresholds for development (LTD) for oviposition and hatching were 6.5 and 9°C, respectively. The number of degree days required for oviposition and hatching was 173 and 588, respectively. Replete females placed in the field on 2 December through to 8 March deposited eggs from 2 February through to 24 April; the eggs commenced hatching between 2 July and 21 August. Unfed larvae from two of 20 egg masses survived through the winter and fed readily when exposed to deer mice (Peromyscus maniculatus) on 22 April. Replete larvae were returned to the field and moulted between 9 and 21 August. Larvae exposed to deer mice in August, 4 weeks after hatching, also fed readily. Although further studies are needed to clarify the timing of nymphal development, the present study suggests that I. pacificus requires more than 1 year to complete its life cycle.     

Hatching rhythms of Uca thayeri Rathbun: timing in semidiurnal and mixed tidal regimes

We compared the timing of larval release by Uca thayeri exposed to different tidal regimes. Crabs on Florida's East Coast experience semidiurnal tides, whereas crabs on the Florida's West Coast experience mixed tides.

In both populations, hatching occurred shortly after high tide. On the East Coast, most crabs released their larvae between dusk and midnight, a few days before the maximum amplitude spring tides. On the West Coast, most crabs released their larvae during the afternoon tropic tides of greater amplitude. West Coast crabs may release during the day because ebbing tides at night are too weak for effective transport. Thus, at each location, hatching occurs when phase relationships between the ebbing tides, the light–dark cycle, and tidal amplitude are most favorable. Further study is required to determine whether females on each Coast show fixed responses to each tidal regime, or whether they can alter their hatching rhythms upon exposure to different tides.