Assessing long-term effects of artificial light at night on insects: what is missing and how to get there

Widespread and significant declines of insect population abundances and biomass are currently one of the most pressing issues in entomology, ecology and conservation biology. It has been suggested that artificial light at night is one major driver behind this trend. Recent advances in the gathering and analysis of long-term data sets of insect population and biomass trends, however, have mostly focused on the effects of climate change and agricultural intensification. We posit here that adequate assessment of artificial night at light that would be required to evaluate its role as a driver of insect declines is far from trivial. Currently its implementation into entomological monitoring programmes and long-running ecological experiments is hampered by several challenges that arise due to (i) its relatively late appearance as a biodiversity threat on the research agenda and (ii) the interdisciplinary nature of the research field where biologists, physicists and engineers still need to develop a set of standardised assessment methods that are both biologically meaningful and easy to implement. As more studies that address these challenges are urgently needed, this article aims to provide a short overview of the few existing studies that have attempted to investigate longer-term effects of artificial light at night on insect populations. To improve the quality and relevance of studies addressing artificial light at night and its effect on insects, we present a set of best practise recommendations where this field needs to be heading in the coming years and how to achieve it

A Study on SPICE Modeling of Non-Resonant Plasmonic Terahertz Detector

Department Of Electrical EngineeringThe terahertz (sub-millimeter wave) is the frequency resource, ranging from 100 GHz ~ 10 THz band, located in the middle region of the infrared and millimeter waves in the electromagnetic spectrum. Terahertz waves has unique physical characteristics, which is transparency of radio waves and straightness of light waves, simultaneously. The terahertz wave is applied to the basic science, such as device, spectroscopy, and imaging technology. And also adjust in the applied science, such as biomedical engineering, security, environment, information and communication. Which importance already verified. In the new shape of future market is expected to be formed broadly. For this application, operating in the THz frequency detecting device essential. Recently, Current elements operating in terahertz are present, such as compound semiconductor (???-???HBT, HEMT). But, there are disadvantage to use as a high price. Therefore, research have been made of silicon based THz detector in many research groups. Silicon-based nano-technology utilizes a plasma wave transistor technology. Which is using the space-time change of the channel charge density. That causes plasma wave oscillation in the MOSFET (Metal oxide semiconductor field effect transistor) channel and this effect available MOSET operating terahertz regime beyond MOSFET cut-off frequency. So, PWT (plasma wave transistor) is available terahertz detection and oscillation. For integrated possible post processing circuit development in these of terahertz applications system, silicon based PWT compact model is essential thing. For this compact model for spice simulation beyond cut-off frequency, we consider charge time variance model which is NQS (non-quasi-static) model, not quasi-static model. For NQS model two kinds of model exist, first is RC ladder model. That is seral connect MOSFET get rid of parasitic elements. And these complex circuit making the equivalent circuit model, it called New Elmore model. For post processing circuit simulation, fast simulation speed is essential, RC ladder model has a disadvantage (for simulating each segment). In this thesis we using New Elmore model based on Non-resonant plasmonic THz detector modeling, And verified physical validity of our NQS model using the our TCAD model based on Quasi-plasma 2DEG. And we propose fast and accurate compact modelingope

Testing a global standard for quantifying species recovery and assessing conservation impact.

Recognizing the imperative to evaluate species recovery and conservation impact, in 2012 the International Union for Conservation of Nature (IUCN) called for development of a "Green List of Species" (now the IUCN Green Status of Species). A draft Green Status framework for assessing species' progress toward recovery, published in 2018, proposed 2 separate but interlinked components: a standardized method (i.e., measurement against benchmarks of species' viability, functionality, and preimpact distribution) to determine current species recovery status (herein species recovery score) and application of that method to estimate past and potential future impacts of conservation based on 4 metrics (conservation legacy, conservation dependence, conservation gain, and recovery potential). We tested the framework with 181 species representing diverse taxa, life histories, biomes, and IUCN Red List categories (extinction risk). Based on the observed distribution of species' recovery scores, we propose the following species recovery categories: fully recovered, slightly depleted, moderately depleted, largely depleted, critically depleted, extinct in the wild, and indeterminate. Fifty-nine percent of tested species were considered largely or critically depleted. Although there was a negative relationship between extinction risk and species recovery score, variation was considerable. Some species in lower risk categories were assessed as farther from recovery than those at higher risk. This emphasizes that species recovery is conceptually different from extinction risk and reinforces the utility of the IUCN Green Status of Species to more fully understand species conservation status. Although extinction risk did not predict conservation legacy, conservation dependence, or conservation gain, it was positively correlated with recovery potential. Only 1.7% of tested species were categorized as zero across all 4 of these conservation impact metrics, indicating that conservation has, or will, play a role in improving or maintaining species status for the vast majority of these species. Based on our results, we devised an updated assessment framework that introduces the option of using a dynamic baseline to assess future impacts of conservation over the short term to avoid misleading results which were generated in a small number of cases, and redefines short term as 10 years to better align with conservation planning. These changes are reflected in the IUCN Green Status of Species Standard

Long-Term Comparison of Attraction of Flying Insects to Streetlights after the Transition from Traditional Light Sources to Light-Emitting Diodes in Urban and Peri-Urban Settings

Among the different light sources used for street lighting, light-emitting diodes (LEDs) are likely to dominate the world market in the coming years. At the same time, the spectral composition of nocturnal illumination is changing. Europe and many other areas worldwide have implemented bans on energy-inefficient lamps, such as the still very common mercury vapor lamps. However, the impact of artificial light on insects is mostly tested with light-traps or flight-intercept traps that are used for short periods only. By comparing the numbers of insects attracted by street lamps before and after replacing mercury vapor light sources (MV) with light emitting diodes, we assessed the impact in more typical (urban and peri-urban) settings over several years. We found that LED attracted approximately half of the number of insects compared to MV lights. Furthermore, most insect groups are less drawn by LED than by MV, while Hymenoptera are less attracted by MV than by LED. Thus, the composition of the attracted communities differed between the light sources, which may impact ecosystem processes and functions. In green peri-urban settings more insects are attracted than in an urban setting, but the relative difference between the light sources is the same.Peer Reviewe

Experimental illumination of natural habitat: How does artificial light influence daily and seasonal timing?

Artificial illumination has increased dramatically over the last few decades. In natural habitat, anthropogenic light at night may lead to changes in species composition and differences in population densities. On the individual level, the presence of artificial light may disturb the temporal organization of daily and seasonal activity. Although there is a gradual increase in knowledge on the impact of artificial light, most studies so far are correlative and make use of existing illumination. In order to experimentally study the ecological effects of artificial illumination and to assess whether these effects depend on the spectral composition of the light, we have set up a worldwide unique, large-scale research project at eight study sites in natural areas in the Netherlands. On each site, we illuminate a forest edge along three 0.5 ha transects with white, red, and green light, and leave one transect dark. Since early 2011, we have assessed the presence of many species and species groups at all sites. Birds, mice, bats, moths, ground-dwelling insects and plants are monitored following rigid protocols; where possible we do this automatically with special equipment. Since early 2012, the lights are on from dusk to dawn and we continue to measure biodiversity and species density until the end of 2014. We study many more effects of light in different species groups; and a key element of the project is the assessment of temporal changes in physiology and behaviour. Each year, we monitor the laying date and breeding success of nest-box breeding bird species. Daily activity patterns of birds are recorded with the use of transponders and transponder readers around the nest box entrances. With automatic cameras and ultrasound recorders, we follow the activity patterns of mice and bats, respectively. Here we show the first effects of light in our experimental setup on the seasonal behaviour of birds breeding at the sites, and daily activity patterns in mice. In order to maximally utilize our setup, and to gain as much information as possible on ecological changes in response to illumination, we encourage other scientists to do research at our illuminated field sites

Data from: Dietary changes in predators and scavengers in a nocturnally illuminated riparian ecosystem

Aquatic and terrestrial ecosystems are linked by fluxes of carbon and nutrients in riparian areas. Processes that alter these fluxes may therefore change the diet and composition of consumer communities. We used stable carbon isotope (δ13C) analyses to test whether the increased abundance of aquatic prey observed in another study led to a dietary shift in riparian consumers in areas illuminated by artificial light at night (ALAN). We measured the contribution of aquatic-derived carbon to diets in riparian arthropods in experimentally lit and unlit sites along an agricultural drainage ditch in northern Germany. The δ13C signature of the spider Pachygnatha clercki (Tetragnathidae) was 0.7‰ lower in the ALAN-illuminated site in summer, indicating a greater assimilation of aquatic prey. Bayesian mixing models also supported higher intake of aquatic prey under ALAN in summer (34% versus 21%). In contrast, isotopic signatures for P. clercki (0.3‰) and Pardosa prativaga (0.7‰) indicated a preference for terrestrial prey in the illuminated site in summer. Terrestrial prey intake increased in spring for P. clerckii under ALAN (from 70% to 74%) and in spring and autumn for P. prativaga (from 68% to 77% and from 67% to 72%) and Opiliones (from 68% to 72%; 68% to 75%). This was despite most of the available prey (up to 80%) being aquatic in origin. We conclude that ALAN changed the diet of riparian secondary consumers by increasing the density of both aquatic and terrestrial prey. Dietary changes were species- and season-specific, indicating that the effects of ALAN may interact with phenology and feeding strategy. Because streetlights can occur in high density near freshwaters, ALAN may have widespread effects on aquatic-terrestrial ecosystem linkages

Do Wild Great Tits Avoid Exposure to Light at Night?

Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their nighttime light exposure by seeking dark spots within illuminated areas. This uncertainty makes it difficult to attribute effects to a direct effect of light at night, or to indirect effects, e.g., via an effect of light at night on food availability. In this study, we aim to quantify the nocturnal light exposure of wild birds in a previously dark forest-edge habitat, experimentally illuminated with three different colors of street lighting, in comparison to a dark control. During two consecutive breeding seasons, we deployed male great tits (Parus major) with a light logger measuring light intensity every five minutes over a 24h period. We found that three males from pairs breeding in brightly illuminated nest boxes close to green and red lamp posts, were not exposed to more artificial light at night than males from pairs breeding further away. This suggests, based on our limited sample size, that these males could have been avoiding light at night by choosing a roosting place with a reduced light intensity. Therefore, effects of light at night previously reported for this species in our experimental set-up might be indirect. In contrast to urban areas where light is omnipresent, bird species in non-urban areas may evade exposure to nocturnal artificial light, thereby avoiding direct consequences of light at night