Hours Of Darkness Research Articles

Researchers Uncover Genetic Link Between Sleep, Seasonal Depression

Back to table of contents Previous article Next article Clinical and Research NewsFull AccessResearchers Uncover Genetic Link Between Sleep, Seasonal DepressionNick ZagorskiNick ZagorskiSearch for more papers by this authorPublished Online:15 Apr 2016https://doi.org/10.1176/appi.pn.2016.4a17AbstractAnalysis of a family with a history of advanced sleep phase disorder and seasonal affective disorder points to the role of the gene PER3 in both conditions.Researchers have long recognized that sleep and mood go hand in hand; patients with depression often experience too much or too little sleep, and sleep deprivation can alter mood. Yet, the molecular basis of this connection has remained unknown.iStock/spfdigitalA research team at the University of California, San Francisco (UCSF), recently identified a gene that they believe could provide a link between sleep and mood regulation. The researchers found a mutation in a critical circadian gene called PERIOD3 (PER3) when analyzing the genomes of several members of an extended family with high rates of seasonal affective disorder (SAD) and familial advanced sleep phase disorder (FASP)—a condition in which people have an accelerated biological clock (that is, slightly less than 24 hours).“People with this disorder would naturally drift in time, going to bed and waking up a little earlier each day,” explained study coauthor Louis Ptáček, M.D., a professor of neurology at the UCSF School of Medicince. “Obviously, the constraints of human society do not allow for that, and that leads to poor sleep behaviors.” In turn, noted Ptáček, the lack of quality sleep can lead to many physical and mental problems. To understand how PER3 affects circadian rhythm and mood, the researchers engineered a strain of mice with the PER3 mutation. When exposed to a normal light-dark cycle (12 hours of light, 12 hours of darkness), the mice with the PER3 mutation behaved similarly to mice without the mutation. However, when the mice were exposed to light for only four hours and darkness for 20 hours, the mice started showing delays in their regular routines of activity and rest compared with control animals under the same conditions. The PER3 mutant mice also showed more depression-like symptoms than mice without the mutation during the periods of extended darkness, as observed in the tail suspension test (the mice with the PER3 mutation spent more time immobile). Treating the animals with the antidepressant imipramine led to a decrease in the depressive-like symptoms.Ying-Hui Fu, Ph.D., a neurology professor at UCSF and coauthor of the study, told Psychiatric News that the role of the period gene family in circadian disorders has been studied for a while, but few paid much attention to PER3.“Evolutionarily, PER3 is just a little different from PER1 and PER2, which are the key components of the 24-hour clock. When PER3 is knocked out in mice, the circadian disruptions are not as strong as with those other two genes, so it has been somewhat ignored,” she said.“But this discovery suggests that while PER3 may not be as critical on the sleep side, it might be a nexus connecting sleep and mood,” she continued. Their findings were published February 22 in the Proceedings of the National Academy of Sciences.While the PER3 mutation has been identified in only one family to date, Ptáček believes that this work holds broader significance; he pointed out that genomewide studies looking for depression risk factors among the general population have repeatedly identified genetic polymorphisms, or variants, near the PER3 region. “No one has been able to prove that these variants specifically affected PER3, but with our new data, the findings from these genomewide studies suddenly become more believable,” he said.This work was supported by multiple grants from the National Institutes of Health. ■An abstract of “A PERIOD3 Variant Causes a Circadian Phenotype and Is Associated With a Seasonal Mood Trait” can be accessed here. ISSUES NewArchived

Characterizing diversity and variation in fish choruses in Darwin Harbour

AbstractThe diversity, intensity, and periodicity of fish sounds can provide a wealth of information on spatial and temporal distribution of soniferous fish and, on occasion, which environmental factors these choruses are driven by. Such information can help predict species presence and understand their movement patterns in the long term. At three sites in Darwin Harbour, Australia, sea-noise loggers on the harbour floor recorded ambient noise over a 2-year period. Many fish calls and nine different chorus types were detected over 50 Hz to 3 kHz. Source species were speculated for four of the choruses and source levels, a precursor to passive acoustic abundance estimates, were identified for two of these. Other calls displayed similarities to choruses detected elsewhere in Australia. All choruses displayed diel cycles with semi-lunar patterns present for three of the chorus types. Time of sunset and temperature were also significantly related to the presence of the most predominant chorus and while not statistically significant, height of high tide and salinity also appeared related. A lack of frequency and temporal partitioning in calling across the choruses in hours of darkness (after sunset) illustrates the complexity of monitoring communities of different vocal species. The study has outlined some of the patterns biological sounds exhibit, which has significant implications for sampling strategies when using soundscapes for temporal and spatial predictive modelling.

Effects of chronic forced circadian desynchronization on body weight and metabolism in male mice.

Metabolic functions are synchronized by the circadian clock setting daily patterns of food intake, nutrient delivery, and behavioral activity. Here, we study the impact of chronic jet‐lag (CJL) on metabolism, and test manipulations aimed to overcome potential alterations. We recorded weight gain in C57Bl/6 mice under chronic 6 h advances or delays of the light–dark cycle every 2 days (ChrA and ChrD, respectively). We have previously reported ChrA, but not ChrD, to induce forced desynchronization of locomotor activity rhythms in mice (Casiraghi et al. 2012). Body weight was rapidly increased under ChrA, with animals tripling the mean weight gain observed in controls by day 10, and doubling it by day 30 (6% vs. 2%, and 15% vs. 7%, respectively). Significant increases in retroperitoneal and epidydimal adipose tissue masses (172% and 61%, respectively), adipocytes size (28%), and circulating triglycerides (39%) were also detected. Daily patterns of food and water intake were abolished under ChrA. In contrast, ChrD had no effect on body weight. Wheel‐running, housing of animals in groups, and restriction of food availability to hours of darkness prevented abnormal increase in body weight under ChrA. Our findings suggest that the observed alterations under ChrA may arise either from a direct effect of circadian disruption on metabolism, from desynchronization between feeding and metabolic rhythms, or both. Direction of shifts, timing of feeding episodes, and other reinforcing signals deeply affect the outcome of metabolic function under CJL. Such features should be taken into account in further studies of shift working schedules in humans.

Does the influence of risk factors on accident occurrence change over time?

A large number of studies have been made to assess the relationship between risk factors and accident occurrence. A risk factor is any factor that makes an accident more likely to occur. Very many risk factors have been identified, for example, being under the influence of alcohol while driving, driving on slippery roads, entering complex junctions, or driving in hours of darkness. Few studies have been made to determine whether the associations between risk factors and accident occurrence remain stable over time. This paper presents examples of studies that have replicated estimates of risk. All these studies were made within a given country, using the same method, to ensure that estimates of risk are comparable. The risk factors included in the paper are: daylight, horizontal curves, junctions, road surface conditions, precipitation, drinking and driving and driver age. For all these risk factors, their association with accidents has changed over time, mostly becoming weaker. A protective factor, snow depth, is also included. Its protective effect has become smaller over time. Possible reasons for the weakening influence of risk factors are discussed.

Spatial and Temporal Variations in the Occurrence and Foraging Activity of Coastal Dolphins in Menai Bay, Zanzibar, Tanzania.

Understanding temporal patterns in distribution, occurrence and behaviour is vital for the effective conservation of cetaceans. This study used cetacean click detectors (C-PODs) to investigate spatial and temporal variation in occurrence and foraging activity of the Indo-Pacific bottlenose (Tursiops aduncus) and Indian Ocean humpback (Sousa plumbea) dolphins resident in the Menai Bay Conservation Area (MBCA), Zanzibar, Tanzania. Occurrence was measured using detection positive minutes. Inter-click intervals were used to identify terminal buzz vocalisations, allowing for analysis of foraging activity. Data were analysed in relation to spatial (location) and temporal (monsoon season, diel phase and tidal phase) variables. Results showed significantly increased occurrence and foraging activity of dolphins in southern areas and during hours of darkness. Higher occurrence at night was not explained by diel variation in echolocation rate and so were considered representative of occurrence patterns. Both tidal phase and monsoon season influenced occurrence but results varied among sites, with no general patterns found. Foraging activity was greatest during hours of darkness, High water and Flood tidal phases. Comparisons of echolocation data among sites suggested differences in the broadband click spectra of MBCA dolphins, possibly indicative of species differences. These dolphin populations are threatened by unsustainable fisheries bycatch and tourism activities. The spatial and temporal patterns identified in this study have implications for future conservation and management actions with regards to these two threats. Further, the results indicate future potential for using passive acoustics to identify and monitor the occurrence of these two species in areas where they co-exist.

A fresh initiative on the use of daylight magnetic particle inspection for the inspection of underwater steel structures

Underwater magnetic particle inspection (MPI) was a common non-destructive testing (NDT) method in the early days of North Sea oil and gas development (in the 1970s/early 1980s). It was primarily used to find cracks in nodal welds on offshore structures. Underwater MPI was carried out using fluorescent inks, which were visible under ultraviolet (UV) light and had to be carried out in the hours of darkness. This led to lengthy and costly inspection programmes, as the inspection work was generally done during the summer months, with perhaps only 4 h of darkness in the northern North Sea. The use of underwater MPI declined from the late 1980s for about 25 years but is now making a comeback. As offshore structures age and exceed their original design lives, the spectre of fatigue cracks has led to the need for detailed node weld inspection. During the last 25 years, MPI inks have changed. Although they conform to the relevant international standards, these standards are for topsides use and thus not necessarily applicable to underwater conditions. Recent trials have been conducted to determine the suitability of available inks to increasing white light levels underwater. This paper presents the work and discusses the findings, which have application worldwide.

The effect of temperature on foraging activity and digestion in the American lobster Homarus americanus (Milne Edwards, 1837) (Decapoda: Nephropsidae) feeding on blue mussels Mytilus edulis (Linnaeus, 1758)

The foraging activity and digestive processes of the American lobster Homarus americanus , feeding on blue mussels, Mytilus edulis were investigated over a temperature range of 5-15°C. Lobsters ate more food with increasing temperature, consuming maximal levels of approximately 5% of their body mass of mussel flesh in one sitting in 15°C water. When foraging behaviour was observed over 7 days, lobsters were more active outside of their shelter at 10 and 15°C and consumed more mussels at these two temperatures. Although lobsters were more active during the hours of darkness, they still exited shelters and fed during the light period if food was available. The lobsters consumed at least one mussel every 15.8, 7.8, and 4.7 h in temperatures of 5, 10, and 15°C, respectively. The passage of a mussel meal through the digestive system of lobsters was considerably slower compared with other decapod crustaceans. Transit rate decreased as the temperature was increased, with clearance times of 252, 133 and 69 h in temperatures of 5, 10, and 15°C. Although the time between feeding bouts decreased with increasing temperature, at the time of next feeding the amount of food that had been cleared from the foregut was the same in each temperature (approximately 20%), suggesting that this proportion of stomach emptying could be the cue for next feeding. Recent work has suggested that lobster numbers increase in the presence of mussel aquaculture operations. This work gives further insight into the feeding behaviour and activity around mussel farms, and suggests that lobsters could be an effective means of removing moribund mussels that could be lost during the harvesting process.

Effect of Native Mexican Isolates ofIsaria fumosorosea(Wize) Brown & Smith1onSpodoptera exigua(Hübner) andHelicoverpa zea(Boddie)2

Abstract. The aim of this study was to evaluate pathogenicity and effect of four isolated native and a strain of Isaria fumosorosea on beet armyworm, Spodoptera exigua (Hubner), and corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). Bioassays in a laboratory used neonate larvae of beet armyworm and corn earworm reared on artificial diet, which were inoculated by spraying or immersing with suspensions of 1 × 108 ml-1 conidia of I. fumosorosea, and subsequently incubated at 26°C, 65 ± 5% relative humidity, and 14:10 light: dark hours. Isolated HIB-30 killed the most immersed corn earworms, but fewest beet armyworms. HIB-30 most disrupted metamorphosis, 40%, by immersing beet armyworms, while HIB-29 and Pfr-612 least interrupted metamorphosis (8%), by spraying and immersing, respectively.

Fungi associated with seeds of two varieties of spinach beet and their possible control in vitro by fungicide treatment

Seeds of Two spinach beet varieties namely; Fordhook giant and Lucullus obtained from commercial markets around Gaborone were used for detection of seed-borne fungi and their possible control in vitro by fungicide. Four hundred seeds of each variety were surface sterilized with 5% sodium hypochlorite for five minutes before placing them on moist filter paper and agar plates (10 seeds/90 cm Petri plate), and incubated at 24±2o C for 12 hours under light and 12 hours in darkness. Five seed borne fungi were recovered after seven days of incubation. The isolated fungi included Aspergillus niger, Aspergillus fumigatus, Penicillium digitatum, Cercospora beticola, and Arthrinum phaeospermum. The fungi detected reduced the germination percentage of seeds. Aspergillus niger was the dominant (95% in Fordhook giant) recovered from the seeds followed by Aspergillus fumigatus (49%) and Penicillium digitatum (14%) . The incidence percentage of Cercospora beticola and Arthrinum phaeospermum. were very low. The effects of fungicides were studied in vitro and the fungicides used were Dithane M-45, and copper oxychloride. Both fungicides were not so effective in reducing fungal incidence and increasing seed germination. Dithane M-45 increased percentage germination in Fordhook giant but failed to do so in Luculus.

Decreased Flight Activity in Culex pipiens (Diptera: Culicidae) Naturally Infected With Culex flavivirus.

Insect-specific flaviviruses (ISFVs) commonly infect vectors of mosquito-borne arboviruses. To investigate whether infection with an ISFV might affect mosquito flight behavior, we quantified flight behavior in Culex pipiens L. naturally infected with Culex flavivirus (CxFV). We observed a significant reduction in the scotophase (dark hours) flight activity of CxFV-positive mosquitoes relative to CxFV-negative mosquitoes, but only a marginal reduction in photophase (light hours) flight activity, and no change in the circadian pattern of flight activity. These results suggest that CxFV infection alters the flight activity of naturally infected Cx. pipiens most dramatically when these vectors are likely to be host seeking and may therefore affect the transmission of medically important arboviruses.

Diurnal changes in ouabain-sensitive Na+,K+-ATPase activity in the rat spinal dorsal horn

Ouabain-sensitive Na+,K+-ATPase (NKA) catalyses active Na+/K+ exchange, and it is responsible for the Na+/K+ gradient across the plasma membrane, cell volume control and membrane excitability and it has been associated to nociception in the spinal dorsal horn (SDH). Several tissues show diurnal changes in NKA activity with important physiological consequences. To test the possibility of diurnal changes in NKA activity in the SDH, every 2 hours, 2 adult (~300 g) male Sprague-Dawley rats housed at a 12: 12 h light: darkness schedule were anesthetized (thiobarbital) and laminectomized (T11–L5), to extract the lumbar spinal cord. Micropunches of SDH (1 mm o) were taken from coronal sections of the spinal cord, and their homogenates were tested for protein concentration and NKA activity. The NKA activity exhibited a highly significant rhythm with a 21.2 h period (P < 0.005; robustness = 57.9%, diurnal fit P < 0.02), a peak at 15.93 h and a 24 h mean value of 638.3 nmol P i mg prot–1 min–1, with an amplitude of oscillation of 71.0 nmol P i mg prot–1 min–1. Light hours show significantly higher ATPase activity values than dark hours (660.9 ± 51.0 vs 608.4 ± 12.8 nmol P i mg prot–1 min–1; P = 0.03). Thus, ouabain-sensitive NKA in SDH displays an intense diurnal activity that could be an important factor in pain and sensory diurnal changes.

Assessing fine-scale diel movement patterns of an exploited coral reef fish

Understanding movement patterns of species requires that the spatial and temporal scales of experimental designs are appropriate to the proposed ecological questions. Previous research on large-scale movements of the exploited reef fish Lethrinus miniatus suggested that adult individuals may use coral reef slope habitat during the day, shifting to adjacent deeper sandy habitat at night. However, investigation of movement at a fine spatial and temporal scale is required to verify this diel activity pattern. Using a closely positioned acoustic telemetry system, movements of 11 L. miniatus were monitored among habitats from the reef crest, to reef slope and deeper adjacent sandy habitat over 3 months. Fine-scale movement patterns among these habitats were compared among four different 3 h periods of the day: dawn, day, dusk and night. Initial observations demonstrated significantly larger horizontal core areas and vertical areas of extent during crepuscular and night periods compared to during the day. Vertical space use (core area and extent) was consistently larger during dawn, dusk and night compared to during the day. Area of activity space extent within the water column and proportional overlap among areas used during different periods of the day varied among weeks, and displayed a pattern consistent with full moon periods. Although previous evidence suggested that L. miniatus adults may shift to deeper habitats adjacent to the reef slope at night, greater space use across the shallow crest to deeper sand habitat was observed during dawn, dusk and night periods. Increased luminosity during dawn, dusk and night periods may cause L. miniatus to utilise a larger search area for foraging. While further research is required to confirm foraging during the hours of twilight and darkness, this fine-scale approach identified patterns in nocturnal activity for an important reef teleost. Knowledge of these temporal and spatial differences in L. miniatus behaviour and movement are important to understanding how this species coexists within ecological niches.

Modeling The Effects of Disability Glare on Trailer Side Underride Crashes

Those of us who practice in the forensic area are aware that many litigated vehicle crashes occur during hours of darkness, when visual cues that alert drivers to hazards are either missing or compromised due to the characteristics of headlights. One particular type of crash of interest to forensic practitioners is a passenger vehicle driving beneath a trailer that is positioned across the roadway during a backing or pullout maneuver. In addition to the loss of certain visual cues, such crashes are frequently characterized by the presence of the tractor pulling the trailer being located in the oncoming travel lane. This may appear to the oncoming motorist to be a benign situation, i.e., a vehicle approaching in the adjacent travel lane. The headlights of the tractor not only provide a false cue to the oncoming motorist, they are also a source of disability glare. In this paper, we model the effects of disability glare during a typical crash scenario. Despite efforts to bias the analysis to minimize the effects of disability glare, it is clear that such glare may hide the presence of the trailer until the oncoming vehicle is relatively close to it, thus reducing the chance of the oncoming driver to avoid an underride collision.

Effect of simulated tidal currents on the burrow emergence rhythms of the Norway lobster (Nephrops norvegicus)

Light is the most important zeitgeber for the synchronization of biological rhythms in terrestrial organisms. In the sea, the light intensity progressively decreases, and tidal currents might control behavioural rhythms at disphotic depths. The Norway lobster, Nephrops norvegicus, is distributed from the upper shelf to middle slope areas. Its burrowing behaviour is under the control of a circadian system, and the effects of tidal currents have been inferred from catchability patterns. Male lobsters were collected from 100 m depth off the Ebro Delta, Tarragona, Spain (40° 39′N, 1° 13′E). Light intensity and water current cycles were simulated in the laboratory to investigate their combined effects on burrow emergence behavioural rhythms (June–July 2012). Periodic water currents (10 cm s−1) inhibited N. norvegicus burrow emergence to a degree dependent on the relative phase between light and water current cycles. The lobsters preferred to remain inside the burrow in the presence of water currents. However, when they were outside the burrow, they spent more time orientated downstream during darkness hours. Moreover, four of the 15 lobsters showed that a current could act as a putative zeitgeber for the circadian oscillator, but further experiments are needed to confirm this finding. These results indicate that tidal current is an important parameter to consider when interpreting fishery-dependent data and data from video surveys, not only N. norvegicus, but for other deep-water epibenthic species.

Factors associated with single-vehicle and multi-vehicle road traffic collision injuries in Ireland

Generalised linear regression models were used to identify factors associated with fatal/serious road traffic collision injuries for single- and multi-vehicle collisions. Single-vehicle collisions and multi-vehicle collisions occurring during the hours of darkness or on a wet road surface had reduced likelihood of a fatal/serious injury. Single-vehicle ‘driver with passengers’ collisions occurring at junctions or on a hill/gradient were less likely to result in a fatal/serious injury. Multi-vehicle rear-end/angle collisions had reduced likelihood of a fatal/serious injury. Single-vehicle ‘driver only’ collisions and multi-vehicle collisions occurring on a public/bank holiday or on a hill/gradient were more likely to result in a fatal/serious injury. Single-vehicle collisions involving male drivers had increased likelihood of a fatal/serious injury and single-vehicle ‘driver with passengers’ collisions involving drivers under the age of 25 years also had increased likelihood of a fatal/serious injury. Findings can enlighten decision-makers to circumstances leading to fatal/serious injuries.

Solar Powered Intelligent Street Lighting System Based on Fuzzy Logic Controller

Intelligent Street lighting control system reduces the power consumption to a large extent. Dimming of lights based on natural light intensity helps in the reduction of power consumed. However, the wastage of power during meagre road usage in dark hours has to be addressed. In this paper, a novel fuzzy logic based controller is proposed to reduce the consumption of power when there is no vehicle travelling on the road during dark hours. By experimental analysis, it is proved that this system effectively reduces the power consumed by the street light.

Without courage, the other Cs will crumble

national monument stands in St Martin’s Lane, London, to a First World War heroine who saved hundreds of Allied soldiers from capture during the First World War. Edith Cavell (18651915) was a British nurse working in Brussels when the German army swept through Belgium in 1914, an act that brought the UK into the war. She is celebrated for nursing soldiers from both sides and for her bravery in helping some 200 Allied troops escape. The night before Nurse Cavell faced the firing squad, she told a chaplain: ‘Patriotism is not enough. I must have no hatred or bitterness for anyone.’ Her courage was not only about making the best of a difficult situation, but she had a strong sense of duty, a duty to alleviating the pain and suffering of those she cared for in their darkest hour. Her courageous devotion to helping the sick and injured extended to caring for those who became hunted and threatened. There are many ways to show courage. The healthcare assistant and assistant practitioner (HCA and AP) is often called on to show courage. Standing up and showing that you care, acting in the best interests of others is courageous and it can also be very difficult. Tough choices often require courage to motivate change. In 1963, Dr Martin Luther King Jr said: ‘The ultimate measure of a man is not where he stands in moments of comfort and convenience, but where he stands at times of challenge and controversy.’ It could be suggested that out of all of the 6 Cs, without courage the other remaining 5 Cs will crumble. The NHS Commissioning Board Chief Nursing Officer and DH Chief Nursing Adviser (2012) suggest courage enables us to do the right thing for those we offer care to, to speak up for them when we have concerns and the personal strength and vision to innovate. The HCA and AP should have the courage to challenge others when they see wrongdoing or when they hear things that compromise their values and beliefs; this is moral courage. Stand up for your beliefs and values and you will improve care and gain peace of mind. Edith Cavell chose this course of action over inaction. To speak out when you see something that is unkind, unfair or wrong is the right thing to do, but this requires courage. When people do not speak out, bad things will continue to happen and people (often the most vulnerable in our society) will continue to get hurt and the harm does not stop. In order to be courageous, speak out when you see poor care, the hasty discharge of an elderly patient with no social support and limited resources and challenge things that you know make you feel uncomfortable: speak up when others remain silent. With some people, being brave may not make you popular, as this reveals their weakness. Being courageous requires you to have the personal strength and vision to innovate and embrace new ways of working. The HCA or AP may have to be courageous in taking the next steps in their careers, for example, having the confidence and courage in taking on personal challenges and stepping into the unknown: be strong, be courageous. Be courageous and: Do the right thing When things are wrong, speak up and question Be influential: when cynics are around, face up to them Be open to those who may challenge you Be brave and make things happen, be innovative Lead by example Do not give up At the end of the day, you have to be able to put your hand on your heart and say, ‘I have done this in the best interests of the patient’. Advocating for a person’s best interests can bring challenges and risks, but the HCA and AP must resolve to uphold their ethical obligations. BJHCA

The Adverse Health Effects of Shift Work in Relation to Risk of Illness/Disease: A Review

Summary Biological rhythm of sleeping is a natural disparity in an organism corresponding to and in reply to cyclic environmental changes, such as daylight hours and hours of darkness or elevated and low down flow. There is some evidence, based upon epidemiological studies as well as studies upon smaller groups of subjects, that individuals who work during the night and sleep during the daytime show cognitive impairment at work, have poorer and fragmented daytime sleep, and have increased risks of developing a wide range of social, psychological, physiological and medical impairments and disorders. Circadian rhythms are one of the most important effective factors on the physiological and physical performances of humans and disturbing this normal rhythm leads to different groups of diseases. The majority of investigations in biological rhythm demeanor vary noticeably in regards to the exact type of disease, population and protocols of sampling over the other outcomes or issues. We conducted a systematic review of [Science Direct, Pubmed, Scopus] to identify influence of different kinds of diseases among shift workers in response to abnormal rhythm of sleeping. The results of this review indicate that abnormal patterns of sleeping can lead to immunological issues, hypertension, metabolic syndrome, insomnia, cardiovascular disease, obesity and depression. It is vital for subsequent investigations to find a way to reduce negative effects (such as decreased amount of works’ time and altered diet) without side effects to help them.

Age-stage, two-sex life history of the golden twin spot moth,Chrysodeixis chalcites(Lepidoptera: Noctuidae), on six commercial tomato cultivars under laboratory conditions

AbstractThe tomato looper,Chrysodeixis chalcites(Esper) (Lepidoptera: Noctuidae), is a major pest that feeds on some fodder crops, vegetables, and ornamental plants in diverse plant families. We studied the effect of different cultivars of tomato including: Cal.JN3, Hed Rio Grande, Rio Grande UG, SUN 6108 f1, Super crystal, and Super strain B on the life history ofC. chalcitesunder laboratory conditions (25±1 °C, 65±5% relative humidity, and 16:8 (light:dark hours). Data were analysed using the age-stage, two-sex life table method. Tomato cultivars had significant effects on developmental time of larvae, pupae, and total preadult stages ofC. chalcites. The longest (17.39 days) and the shortest (13.93 days) larval period were observed on Hed Rio Grande and SUN 6108 f1, respectively. The longest pupal period was observed on Cal.JN3 (12.16 days) and Hed Rio Grande (12.11 days) compared with other cultivars. The lowest amount of larval growth index and rate of ovipositon days was observed on Cal.JN3. The results of this study revealed that Cal.JN3 and Hed Rio Grande were the less suitable cultivars toC. chalcitescompared with other cultivars studied and can be used in integrated pest management programme of this pest.

Timing of nocturnal passerine migration in Arctic light conditions

The nocturnal migration of many passerines starts after sunset and reaches peak intensity during the dark hours of the night. Birds destined for high Arctic breeding grounds encounter a special situation, as they will experience continuous daylight when reaching the high latitudes during the final part of spring migration. How does this affect the pattern of nocturnal migration? We consider three alternative hypotheses; that the period of nocturnal flight activity may become compressed, remain unchanged or become disorganized under Arctic light conditions. We tracked migrating birds by radar north of the Arctic Circle (at Abisko, 68°21′N, 18°49′E, in Swedish Lapland) and show that the pattern during the night, with a migration peak around midnight, persisted even in continuous daylight when the sun remained above the horizon throughout the 24 h of the day. The flight intensity peak under continuous daylight in spring (midnight sun) was very similar to the corresponding peak in autumn, when the migration took place under twilight conditions. The duration of the flight period under continuous daylight in spring lasted 8–10 h and did not seem to be compressed. We hypothesize that the flight period under midnight sun conditions may in fact be more protracted than during short nights, because of release from twilight cues that tend to synchronize initiation and termination of migratory flights. These cues will thus capture and confine the flight period. The results of this provisional study suggest interesting dynamics in timing of nocturnal migratory flights under seasonally and latitudinally changing day length conditions, which will need detailed documentation by future studies of migration intensity at high-latitude sites.