The ontogeny of physiological response to light intensity in early stage spiny lobster (Jasus edwardsii) larvae

Early stage phyllosoma larvae of the spiny rock lobster Jasus edwardsii were examined for swimming speed, feeding, oxygen consumption and nitrogen excretion as instantaneous performance indicators when exposed to different irradiance levels. Swimming speed was measured in recently hatched Stage I larvae while all other parameters were measured in larvae from hatch to mid-Stage V. The swimming speed of recently hatched Stage I phyllosoma increased logarithmically between light intensities of 2.9 x 10(14) and 1.8 x 10(16) quanta s(-1) cm(-2) indicating that, within this range, swimming activity was only suppressed at the lowest irradiance level. Larvae examined under dark (no light) conditions showed lower feed intake, oxygen consumption and nitrogen excretion than larvae under low (7.7 x 10(12) q s(-1) cm(-2)) and high (3.9 x 10(14) q s(-1) cm(-2)) light intensities, and this was a consistent pattern observed throughout development from hatch to Stage V. There was no difference in feeding, oxygen consumption and nitrogen excretion between larvae exposed to low and high light intensities. However, from mid-Stage I to mid-Stage V, the metabolic feeding efficiency (feed intake:oxygen consumption ratio) was consistently higher in larvae exposed to low light intensity than in phyllosoma assessed in the dark and under high irradiance. A light intensity of about 7.7 x 10(12) quanta s(-1) cm(-2) and no higher than 3.9 x 10(14) quanta s(-1) cm(-2) is recommended to stimulate feeding and optimise metabolic feeding efficiency in early larval stages of J. edwardsii.     

Sensitization and habituation of the swimming behavior in ascidian larvae to light

Ascidian larvae of Ciona intestinalis change their photic behavior during the course of development. Newly hatched larvae show no response to a light stimulus at any intensity. At 4 hr after hatching, larvae were induced to start to swimming upon the cessation of illumination, and to stop swimming upon the onset of illumination. At a weaker light intensity (5.0 x 10(-3) J/m (2).s), the larvae showed similar responses to either a single stimulus or repeated stimuli of onset and cessation of light until 10 hr after hatching. At a stronger light intensity (3.2 x 10(-1) J/m(2).s), when the stimulus was repeated, they showed sensitization and habituation of the swimming response. At 3 hr after hatching the larvae failed to show any response to an initial stimulus at any intensity of light, but after several repeated stimuli (sensitization) they showed a swimming response at light intensities above 4.0 x 10(-2) J/m (2).s. At 5 hr and with intensity above 1.0 x 10 (-2) J/m(2).s, the larvae showed photoresponses to the first stimulus, but after several repetitions the larvae failed to stop swimming upon the onset of light (habituation). A repeated series of stimuli at stronger intensities of light caused greater habituation; this habituation was retained for about 1 min. Since the larval central nervous system in Ciona is comprised of only about 100 neurons, learning behavior in ascidian larvae should provide insights for a minimal mechanism of memory in vertebrates.     

Blue biliprotein as an effective factor for cryptic colouration in Rhodinia fugax larvae

The fifth instar larva of the saturniid silkworm, Rhodinia fugax, is light yellowish-green on its dorsal surface and dark green on the ventral surface with a lateral demarcation between the two colours. The larva of R. fugax closely resembles the leaves of the host plant, Quercus serrata, in colour and shape. The spectral reflectance of the larval integument of R. fugax corresponds to that of the Q. serrata leaf. In the larval integument, there is more blue biliproteins (BPs) on the ventral surface than on the dorsal surface. Light intensity influences larval colouration. The larval integuments are green under light conditions (1000 lux), whereas larvae kept in dark conditions (10 lux) turn yellow. The BP-I content of the haemolymph is also affected by light intensity. The quantities of BP-I and its blue chromophore are higher under light conditions than under dark conditions. In contrast, there is little difference in the yellow chromophore content between the two light intensities. When larvae are kept in the light, the BP-I content in the cuticle is higher than under dark conditions in both the ventral and dorsal surfaces, and its chromophore content parallels the BP content. However, the amounts of BP-II and its chromophore in the epidermis show no change with the light intensity. Moreover, the quantity of yellow chromophore in the integument is also not affected by light intensity. Therefore, light stimulates the accumulation of BP-I and its chromophore in the haemolymph and cuticle, whereas the accumulation of BP-II and its chromophore in the epidermis are not influenced by light intensity. These results suggest that BPs and their chromophores determine the larval colouration and may play an important role in the cryptic colouration of R. fugax larvae.     

Wavelength-dependent effects of evening light exposure on sleep architecture and sleep EEG power density in men

Light strongly influences the circadian timing system in humans via non-image-forming photoreceptors in the retinal ganglion cells. Their spectral sensitivity is highest in the short-wavelength range of the visible light spectrum as demonstrated by melatonin suppression, circadian phase shifting, acute physiological responses, and subjective alertness. We tested the impact of short wavelength light (460 nm) on sleep EEG power spectra and sleep architecture. We hypothesized that its acute action on sleep is similar in magnitude to reported effects for polychromatic light at higher intensities and stronger than longer wavelength light (550 nm). The sleep EEGs of eight young men were analyzed after 2-h evening exposure to blue (460 nm) and green (550 nm) light of equal photon densities (2.8 x 10(13) photons x cm(-2) x s(-1)) and to dark (0 lux) under constant posture conditions. The time course of EEG slow-wave activity (SWA; 0.75-4.5 Hz) across sleep cycles after blue light at 460 nm was changed such that SWA was slightly reduced in the first and significantly increased during the third sleep cycle in parietal and occipital brain regions. Moreover, blue light significantly shortened rapid eye movement (REM) sleep duration during these two sleep cycles. Thus the light effects on the dynamics of SWA and REM sleep durations were blue shifted relative to the three-cone visual photopic system probably mediated by the circadian, non-image-forming visual system. Our results can be interpreted in terms of an induction of a circadian phase delay and/or repercussions of a stronger alerting effect after blue light, persisting into the sleep episode.     

Efficacy of Bacillus sphaericus 2362 against larvae of Anopheles gambiae under laboratory and field conditions in West Africa

A flowable concentrate of Bacillus sphaericus (Neide) strain 2362 was applied against Anopheles gambiae Giles s.l. mosquito larve in small plot field trials in Bobo-Dioulasso area. Burkina-Faso. Third and fourth instar larvae were controlled for 10-15 days with a dosage of 10 g/m2, 3-10 days with 1 or 0.1 mg/m2, and 2 days with 0.01 g/m2. Complete elimination of larval populations required 1 x 10(2) to 2 x 10(3) viable spores/ml in the larval feeding zone. After treatment, the total numbers of viable spores decreased in the ponds, due to ingestion of spores by non-target as well as target organisms and/or loss of viability of some spores by sunlight. This formulation was less effective against An. gambiae than against Culex quinquefasciatus Say larvae, both in laboratory bioassays and under field conditions.     

Proximate control of diel vertical migration in Phyllosoma larvae of the Caribbean spiny lobster Panulirus argus

Phyllosoma larvae of the spiny lobster Panulirus argus undergo diel vertical migration (DVM), in which they are at depth during the day and nearer the surface at night. This study determined the visual spectral sensitivity of Stage I larvae and investigated whether light plays a proximate role in DVM as an exogenous cue and as an entrainment cue for an endogenous rhythm in vertical migration. Under constant conditions, larvae have a circadian rhythm (24.5-h period) in vertical swimming that resulted in a twilight DVM pattern. The behavioral response spectrum and electroretinogram recording indicated two photoreceptor spectral classes with maxima at 360 and 486 nm. When stimulated in an apparatus that simulated the underwater angular light distribution, dark-adapted larvae showed only positive phototaxis, with a threshold intensity of 1.8 × 10(13) photons m(-2) s(-1) (3.0 × 10(-5) μmoles photons m(-2) s(-1)). They have an avoidance response to predator shadows in which they descend upon sudden decreases in light intensity of more than 69%. When stimulated with relative rates of decrease in light intensity as occur at sunset they ascended, whereas they descended upon relative rates of light intensity increase as occur at sunrise. Thus, the DVM pattern is controlled by both an endogenous circadian rhythm in swimming and behavioral responses to light at sunrise and sunset.     

Single cell protein production of Euglena gracilis and carbon dioxide fixation in an innovative photo-bioreactor

The biological fixation using microalgae has been known as an effective and economical carbon dioxide reduction technology. Carbon dioxide (CO2) fixation by microalgae has been shown to be effective and economical. Among various algae, a species Euglena gracilis was selected as it has advantages such as high protein content and high digestibility for animal feed. A kinetic model was studied in order to determine the relationship between specific growth rate and light intensity. The half-saturation constant for light intensity in the Monod model was 178.7 micromol photons/m2/s. The most favorable initial pH, temperature, and CO2 concentration were found to be 3.5, 27 degrees C, and 5-10% (vol/vol), respectively. Light intensity and hydraulic retention time were tested for effects on cell yield in a laboratory-scale photo-bioreactor of 100l working volume followed by semi-continuous and continuous culture. Subsequently, an innovative pilot-scale photo-bioreactor that used sunlight and flue gas was developed to increase production of this bioresource. The proposed pilot-scale reactor showed improved cell yield compared with the laboratory-scale reactor.     

蓝光诱导的胶孢炭疽菌(Colletotrichum gloeosporioides)类胡萝卜素积累

胶孢炭疽菌(Colletotrichumgloeosporioides)为一种丝状真菌,蓝光照射可诱导类胡萝卜素的积累。光镜下观察表明,蓝光可诱导胶孢炭疽菌菌丝积累色素颗粒,而黑暗和红光处理却无此现象。类胡萝卜素的积累受蓝光光照强度的影响。28℃且蓝光为6.5μmol.m-2.s-1时,类胡萝卜素积累量可随光照时间延长呈增长趋势,在第5天达到最高峰为71.8μg/g FW,随后含量下降。此外,胶孢炭疽菌在黑暗中预培养的时间也影响蓝光的诱导反应。     

Larval release rhythm of the mole crab Emerita talpoida (Say)

Ovigerous mole crabs Emerita talpoida (Say) were monitored in the laboratory to determine if the time of larval release is synchronous and under endogenous control. To determine the time of larval release, ovigerous females were placed under a 14:10 light/dark cycle simulating the ambient photoperiod. Hatching was rhythmic, occurring as a quick burst lasting about 5-15 min shortly after the onset of darkness. An individual mole crab will release batches of larvae for up to three successive nights, suggesting that the rhythm is under endogenous control. Mole crabs monitored under constant low-level red light displayed the same release pattern with hatching occurring near the time of expected sunset, indicating the presence of a circadian rhythm in larval release. To investigate whether the female or the embryos control hatching, a portion of the egg mass (50-100 embryos) was separated from the female. The time of hatching of the detached embryos subjected to either a still or shaken treatment was compared with the hatching time of embryos still attached to the female. Detached eggs in both treatments hatched within 1.5-2 h of the time of the female-attached eggs, which suggests that embryos control the timing of hatching.     

Photoperiodism and the photic environment of the pitcher-plant mosquito,Wyeomyia smithii

Summary Wyeomyia smithii Coq. (Diptera: Culicidae) overwinters as a larva in a state of diapause which is initiated, maintained, and terminated by photoperiod. Both in the dawn and in the dusk, diapausing larvae are photoperiodically most sensitive to blue light (390–450 nm) with a shoulder in response in the bluegreen and green (480–540 nm) region of the spectrum. The saturation curves for response to blue light in the dusk has a steeper slope than for response to blue-green and green light in the dusk, suggesting two distinct pigments or pigment complexes underly photoperiodic response in W. smithii.The photic environment of W. smithii during twilight is rich in yellow-green light but sufficient light is available at 390–540 nm to trigger photoperiodic response early during morning civil twilight and to sustain response until late in evening civil twilight. Comparison of action spectra with spectra of available light indicates that the zenith angles of the sun which would result in 50% response are 95°48 and 94°52 in the dawn and dusk, respectively. Using these zenith angles to approximate daylength in nature provides a resonable prediction of development in the field.The flux density of photons necessary to elicit 50% development a 454 nm is about 9×10⁷ photons/cm² s in the dawn and 3×10⁸ photons/cm² s in the dusk. This high degree of sensitivity enables W. smithii to cue to the rapidly changing light intensity which occurs around the nautical-civil twilight transition. At the same time, the chromophore is not likely to be stimulated by the light of the full moon.     

Scale-up aspects of photobioreactors: effects of mixing-induced light/dark cycles

The green micro-algae Chlamydomonas reinhardtiiand Dunaliella tertiolecta were cultivated undermedium-duration square-wave light/dark cycles with acycle time of 15 s. These cycles were used to simulatethe light regime experienced by micro-algae inexternally-illuminated (sunlight) air-lift loopbioreactors with internal draft tube. Biomass yieldin relation to light energy was determined as gprotein per mol of photons (400–700 nm). Between 600and 1200 mol m^-2 s^-1 the yield at a10/5 s light/dark cycle was equal to the yield atcontinuous illumination. Consequently, provided thatthe liquid circulation time is 15 s, a considerabledark zone seems to be allowed in the interior ofair-lift loop photobioreactors (33% v/v) without lossof light utilization efficiency. However, at a 5/10 slight/dark cycle, corresponding to a 67% v/v darkzone, biomass yield decreased. Furthermore, bothalgae, C. reinhardtii and D. tertiolecta,responded similarly to these cycles with respect tobiomass yield. This was interesting because they werereported to exhibit a different photoacclimationstrategy. Finally, it was demonstrated that D.tertiolecta was much more efficient at low (average)photon flux densities (57–370 mol m^-2s^-1) than at high PFDs (> 600 mol m^-2s^-1) and it was shown that D. tertiolectawas cultivated at a sub-optimal temperature (20 ^°C).     

不同光照强度下兴安落叶松对舞毒蛾幼虫生长发育及防御酶的影响

为了探讨舞毒蛾对光照环境变化引起的落叶松抗性的变化是如何响应的,分析了不同光照强度处理的兴安落叶松对舞毒蛾幼虫生长发育状况和生理指标变化的影响。研究发现,取食50%和25%光照强度下生长的落叶松后,舞毒蛾幼虫平均体重、蛹重、化蛹率和羽化率与对照组相比均显著下降（P<0.05）。幼虫体内保护酶SOD、POD、CAT和解毒酶ACP、AKP、CarE、GSTs、MFO活性与对照组(100% 光照)相比均显著降低（P<0.05）且除CAT外在50%光照强度下降低最为显著（P<0.05）;4龄和5龄幼虫取食同一光强处理的落叶松后,SOD、POD、CarE、GSTs和MFO活性5龄显著低于4龄（P<0.05）,ACP和AKP活性5龄却显著高于4龄（P<0.05）,表明昆虫在不同的发育阶段启用不同的排毒酶系。光照差异对取食人工饲料的舞毒蛾生长发育和排毒代谢酶活性均没有显著影响,说明舞毒蛾生长发育和酶活性的变化是因寄主植物抗性的影响而非光照强度的作用。本研究结果表明,采取适当的营林措施调节林分内的光照条件,可以提高落叶松的自主抗虫性,增强其抵御害虫危害的能力,有效控制害虫危害,减少化学农药的施用量。     

Effects of light intensity and addition of carotene rich Dunaliella salina live cells on growth and antioxidant activity of Solea senegalensis Kaup (1858) larval and metamorphic stages

Senegal sole Solea senegalensis larval and metamorphic stages were exposed to a range of light intensities (200, 1000 and 2000 lx) in cultures with or without supplementation of β-carotene-rich live Dunaliella salina cells. Antioxidant biomarkers such as superoxide dismutase (SOD), catalase (KAT), total glutathione peroxidase (t-GPX) and malondialdehyde (MDA) were determined in larval and metamorphic stages. Growth was not affected ( P > 0·05) either by light intensity or D. salina supplementation. Survival after metamorphosis was also unaffected by D. salina supplementation (mean ± s . e . 81·0 ± 2·5% against 80·6 ± 2·9% those fed the control algal diet) or light intensity (mean ± s . e . 74·3 ± 4·9% for 200 lx, 85·1 ± 2·7% for 1000 lx and 82·8 ± 5·2% for 2000 lx, respectively). Light intensity affected ( P < 0·05) KAT and t-GPX throughout development. SOD was only affected in metamorphosing larvae. The highest KAT and t-GPX activities were detected when the lowest light intensity (200 lx) was used. Light had no effect ( P > 0·05) on MDA at any stage. Supplementing the diet with D. salina did not affect SOD, KAT or t-GPX and there was no interaction ( P > 0·05) with light intensity. MDA was the only biomarker whose activity was significantly ( P < 0·05) reduced when D. salina was supplemented to the larval rearing tanks. The effect of D. salina supplementation was only detected in metamorphosing larvae, whose MDA levels were noticeably higher than in earlier stages. These results are evidence of the antiperoxidative effect of β-carotene from live algae in the larval rearing process of marine fishes.     

Entrainment of the circadian rhythm in larval release of the crab Dyspanopeus sayi by temperature cycles

Marine and estuarine crabs brood attached eggs, which hatch synchronously releasing larvae at precise times relative to environmental cycles. The subtidal crab Dyspanopeus sayi has a circadian rhythm, in which larvae are released within the 4-h interval after the time of ambient sunset. Previous studies demonstrated that the rhythm can be entrained by the light:dark cycle. Since subtidal crabs are also exposed to temperature fluctuations, an unstudied question was whether the circadian rhythm could be entrained by the diel temperature cycle. To answer this question, ovigerous D. sayi were entrained in darkness to 2.5, 5, and 10 °C temperature cycles that were reverse in phase from the ambient temperature cycle. After entrainment, larval release times were monitored in constant conditions of temperature and darkness with a time-lapse video system. The effectiveness of a temperature cycle to shift the timing of larval release increased as the magnitude of the temperature cycle increased and as crabs were exposed to increasing numbers of entrainment cycles. However, entrainment to a 10 °C cycle only lasted 2 days in constant conditions. When crabs were entrained to a light:dark vs. a 10 °C temperature cycle, the light:dark cycle was dominant for entrainment. Nevertheless, ovigerous crabs do sense temperature cycles and in areas where daylight is too low for entrainment, temperature cycles can be used to regulate the time of larval release.     

Photoinhibition induced alterations in energy transfer process in phycobilisomes of PS II in the cyanobacterium, Spirulina platensis

Exposure of algae or plants to irradiance from above the light saturation point of photosynthesis is known as high light stress. This high light stress induces various responses including photoinhibition of the photosynthetic apparatus. The degree of photoinhibition could be clearly determined by measuring the parameters such as absorption and fluorescence of chromoproteins. In cyanobacteria and red algae, most of the photosystem (PS) II associated light harvesting is performed by a membrane attached complex called the phycobilisome (PBS). The effects of high intensity light (1000-4000 micromol photons m(-2) s(-1)) on excitation energy transfer from PBSs to PS II in a cyanobacterium Spirulina platensis were studied by measuring room temperature PC fluorescence emission spectra. High light (3000 micromol photons m(-2) s(-1)) stress had a significant effect on PC fluorescence emission spectra. On the other hand, light stress induced an increase in the ratio of PC fluorescence intensity of PBS indicating that light stress inhibits excitation energy transfer from PBS to PS II. The high light treatment to 3000 micromol photons m(-2) s(-1) caused disappearance of 31.5 kDa linker polypeptide which is known to link PC discs together. In addition we observed the similar decrease in the other polypeptide contents. Our data concludes that the Spirulina cells upon light treatment causes alterations in the phycobiliproteins (PBPs) and affects the energy transfer process within the PBSs.     

Microhabitat selection by larval Chironomus tentans (Diptera: Chironomidae): effects of predators, food, cover and light

1. As part of a study designed to estimate the developmental costs of antipredator behaviour of larval chironomids, we used laboratory experiments to study effects of food and factors that could influence predation risk [presence of fish, cover from fish (simulated debris) and light level], on microhabitat selection by Chironomus tentans larvae in the third and fourth instar. 2. Larvae were more likely to build tubes where there was more food although their ability to move far to find food appeared limited. 3. Larvae did not avoid areas with fish and the presence of fish did not alter larval response to food. 4. Larvae avoided areas of cover (simulated debris) but cover did not alter larval response to food. 5. When provided with a choice between light and dark areas, larvae initially without tubes were found more often in the dark areas. Light level had no effect on location of larvae that had begun the experiment with tubes. 6. Results suggest the tubicolous life-style of larval Chironomus tentans limits their ability to select microhabitats that could alter their risk of predation.     

Relationship between an increase of juvenile hormone titer in early instars and the induction of diapause in fully grown larvae of Sesamia nonagrioides

The larvae of Sesamia nonagrioides (Lepidoptera: Noctuidae) grown at 25 degrees C and long photoperiod (16:8h light:dark) pupate in the 5th or 6th (mostly) larval instar, while the larvae reared under a short photoperiod (12:12h) enter diapause during which they consume some food and undergo up to 12 (usually 3-4) stationary larval molts. Diapause programming includes an increase of juvenile hormone (JH) titer in the hemolymph from about 20 to 50 nM in the 4th and 5th instar larvae (titer in earlier instars was not measured). JH I, II, and III are present in approximate ratio 1-2:10:1. The JH titer drops to zero before pupation but remains around 20 nM during diapause. Perfect extra larval molts associated with a body weight increase can be induced in the non-diapausing larvae with a JH analogue (JHA). The weight rise is due to accumulation of reserves and not to a general body growth. The timing of extra molts is similar to the molting pattern of the diapausing larvae only when JHA is present since early larval instars. In the diapausing larvae, JHA application affects neither molting periodicity nor the body weight. It is concluded that (1) Increased JH titer in early larval instars is a part of diapause programming; (2) The extension of larval stage in the diapausing larvae, but not the timing pattern of extra molts, is due to continuously high JH titer; (3) The diapause program includes low food intake, maintenance of a certain body weight, and periodic larval molts.     

Sensitivity of the human circadian system to short-wavelength (420-nm) light

The circadian and neurobehavioral effects of light are primarily mediated by a retinal ganglion cell photoreceptor in the mammalian eye containing the photopigment melanopsin. Nine action spectrum studies using rodents, monkeys, and humans for these responses indicate peak sensitivities in the blue region of the visible spectrum ranging from 459 to 484 nm, with some disagreement in short-wavelength sensitivity of the spectrum. The aim of this work was to quantify the sensitivity of human volunteers to monochromatic 420-nm light for plasma melatonin suppression. Adult female (n=14) and male (n=12) subjects participated in 2 studies, each employing a within-subjects design. In a fluence-response study, subjects (n=8) were tested with 8 light irradiances at 420 nm ranging over a 4-log unit photon density range of 10(10) to 10(14) photons/cm(2)/sec and 1 dark exposure control night. In the other study, subjects (n=18) completed an experiment comparing melatonin suppression with equal photon doses (1.21 x 10(13) photons/cm(2)/sec) of 420 nm and 460 nm monochromatic light and a dark exposure control night. The first study demonstrated a clear fluence-response relationship between 420-nm light and melatonin suppression (p<0.001) with a half-saturation constant of 2.74 x 10(11) photons/cm(2)/sec. The second study showed that 460-nm light is significantly stronger than 420-nm light for suppressing melatonin (p<0.04). Together, the results clarify the visible short-wavelength sensitivity of the human melatonin suppression action spectrum. This basic physiological finding may be useful for optimizing lighting for therapeutic and other applications.     

幼虫密度对甜菜夜蛾生长发育与繁殖的影响

为了研究甜菜夜蛾Spodoptera exigua(Hübner)幼虫的密度对其发育及繁殖的影响,本实验观察了5种幼虫密度下（1,5,10,20,30头/瓶）,幼虫发育和成虫繁殖情况。结果表明：幼虫和蛹历期、存活率和蛹重均差异显著。幼虫和蛹历期均以20头/瓶的最短,1头/瓶的最长,其余随幼虫密度增加而延长;幼虫至蛹存活率以10头/瓶的最高,其余随幼虫密度增加而降低;1头/瓶的蛹最重,显著高于其他密度的,其余随幼虫密度增加而下降。尽管密度间成虫羽化率和产卵前期均无显著差异,但成虫产卵量、寿命和畸形率差异显著。1头/瓶的产卵量最多,其次为10头/瓶的,其余随幼虫密度增加而减少,30头/瓶的产卵量显著少于其他密度的; 密度在1～20头/瓶范围内,雌蛾寿命均较短,显著短于30头/瓶的,而雄蛾寿命以5头/瓶的最短,显著短于其他密度的（10头/瓶除外）,10头/瓶的次之,其余密度间差异不显著;不同幼虫密度下羽化的成虫畸形率差异显著,10头/瓶的最低,其余随幼虫密度增加而升高; 生命表结果表明甜菜夜蛾在10头/瓶下世代存活率和种群增长指数均最高,幼虫密度过低或过高均不利于种群增长;世代存活率（S）和种群增长指数（I）与幼虫密度之间的关系均呈抛物线关系：S =－0.2087x²+2.5694x+211.52 (R²=0.88),I=－0.0552x²+0.9166x+54.168 (R²=0.95)。结果提示幼虫密度影响甜菜夜蛾种群动态的重要生态因子之一。     

Induction of metamorphosis of pediveliger larvae of the mussel Mytilus galloprovincialis Lamarck, 1819 using neuroactive compounds, KCl, NH4Cl and organic solvents

Pediveliger larvae of Mytilus galloprovincialis were subjected to a series of bioassays to investigate the induction of metamorphosis using neuroactive compounds, K(+), NH(4)(+) and organic solvents. Growth and survival of post-larvae obtained using ethanol and methanol were also observed. Epinephrine, phenylephrine, clonidine and metanephrine induced larval metamorphosis at 10(-6) to 10(-4) M in both 24-h and continuous exposure assays. In 24-h exposure assays, alpha-methyldopa at 5 x 10(-5) M and methoxyphenamine at 5 x 10(-5)-10(-4) M induced 55-94% metamorphosis. Similarly, excess K(+) at 3 x 10(-2) M induced 39% metamorphosis and NH(4)(+) at 1-5 x 10(-2) M induced 63-78% metamorphosis. The EC50s of seven organic solvents ranged from 0.04 to 0.82 M. Post-larvae that metamorphosed using ethanol and methanol survived as juveniles and grew at the same rate as those from microbial biofilm. Thus, the above compounds can be useful inducers of metamorphosis for antifouling studies using larvae and juveniles of M. galloprovincialis.