Light Preference Research Articles

Effects of Sublethal Exposure to Three Water Pollutants on Scototaxis in Rare Minnow (Gobiocypris rarus)

The biological early warning system with fish behavior as the detection index is an efficient and rapid early warning technology for the ecological damage caused by water pollutants. However, the attempt to apply the scototaxis (dark preference) behavior of fish to biological early warning is still relatively lacking. In this study, we delved into the dark and light preferences of the rare minnows (Gobiocypris rarus), employing three distinct tank configurations. Additionally, we systematically examined the modulating effects of environmental illumination, nutritional status, and the number of test subjects on this behavior, aiming to establish optimal experimental parameters for its observation. Furthermore, cadmium ions [Cd2+], tricaine methanesulfonate [MS222], and p-chloroaniline were employed as representative heavy metal ions, neuroactive agents, and organic toxicants, respectively, to test the impact of chemicals on scototaxis in gradient concentrations. The results demonstrated that the rare minnow exhibited a clear scototaxis (dark preference), and this behavior was not affected by the nutritional status of the test fish, the illumination, or the number of subjects. While the dark chamber was consistently the preferred location of rare minnows during the chemical exposure tests, the degree of scototaxis by the rare minnow significantly decreased at Cd2+ ≥ 3 mg/L, MS222 ≥ 11 mg/L, and p-chloroaniline ≥ 29 mg/L, suggesting a potential disruption of their innate behavioral patterns by these chemicals. These findings underscore the sensitivity of rare minnows to water pollutants. Therefore, the scototaxis behavior of rare minnows can be a potential and useful behavioral indicator for biological early warning, which can be used for early biological warning of sudden water pollution caused by chemicals such as Cd2+, MS222, and p-chloroaniline.

Spontaneous Color Preferences and Associative Learning in Protaetia brevitarsis (Coleoptera: Scarabaeidae).

Color vision, which varies among species, plays an important role in foraging, mating, and habitat selection among insects. Protaetia brevitarsis (Coleoptera: Scarabaeidae, Lewis) is an omnivorous beetle that damages both crops and fruit. Here, to understand the effect of vision and olfaction in host selection, experiments were conducted on the spectral wavelength preference, color preference, and associative learning ability of adult P. brevitarsis using LED lights and grapes. In our experiments, adults showed the strongest spontaneous preference toward the red spectrum, particularly 730 nm. Non-preferred lights were used to train adults with a food reward (grapes). Green-trained adults had an increasing tendency to prefer green light, and blue-trained adults had a clear preference for blue light. Furthermore, adults significantly preferred red grapes in the absence of olfactory cues, but their selectivity for grapes differed in the presence of olfactory cues, indicating that vision was not the only factor in foraging decisions, but that olfactory cues also influenced their decision making. The results lay the groundwork for revealing their host localization mechanism and provide promising avenues for biological control in the field.

Photophysiology of the haploid form of the cryptophyte Teleaulax amphioxeia.

Cryptophytes are abundant and ubiquitous microalgae that constitute a major plastid source for kleptoplastidic ciliates and dinoflagellates. Despite their ecological significance, the understanding of their light preferences and photophysiology remains limited. Here, we provide a comprehensive study of the response of the haploid strain Teleaulax amphioxeia (Cr10EHU) to varying light irradiance. This strain is capable of growing under a wide range of irradiance levels, notably by finely tuning the different pigments bound to the membrane light-harvesting proteins. Analysis of the luminal phycoerythrin content revealed remarkable flexibility, with phycoerythrin emerging as a pivotal protein facilitating acclimation to varying light levels. Detailed ultrastructure examinations unveiled that this adaptability was supported by the synthesis of large thylakoidal vesicles, likely enhancing the capture of green photons efficiently under low light, a phenomenon previously undocumented. Teleaulax amphioxeia Cr10EHU effectively regulated light utilization by using a cryptophyte state transition-like process, with a larger amplitude observed under high growth irradiance. Furthermore, our results revealed the establishment of growth irradiance-dependent non-photochemical quenching of fluorescence, likely inducing the dissipation of excess light. This study underscores the particularities and the significant photoadaptability of the plastid of the haploid form of T. amphioxeia. It constitutes a comprehensive photophysiological characterization of the Cr10EHU strain that paves the way for future studies of the kleptoplastidy process.

Unveiling determinants of household lighting preferences in rural Tanzania: insights for sustainable energy access

This paper investigates the determinants and prospects of household lighting choices in rural Tanzania using a Multinomial Logit Regression Model. The analysis is based on data from 4671 households, focusing on three lighting options: electricity, solar energy, and candle lighting. The results reveal significant factors influencing these choices, including household head characteristics, household size, marital status, education, employment status, number of rooms, and income. Key findings indicate that the age of the household head negatively influences the likelihood of choosing grid-electricity, while having a male head of household significantly reduces the probability of opting for any lighting option. Larger household size is negatively associated with choosing electricity and candle lighting. Marital status shows that married households are more likely to use candle lighting. Employment status positively impacts the likelihood of adopting all three lighting options, with employed household heads being more likely to choose modern lighting solutions. Income levels are crucial, as higher income significantly increases the probability of selecting electricity and candle lighting, but not solar energy. These findings provide valuable insights for policymakers and stakeholders aiming to enhance sustainable energy access in rural Tanzania. It highlights the importance of addressing socio-economic factors to promote the adoption of modern and sustainable lighting technologies.

Hyperactive mTORC1 disrupts habenula function and light preference in zebrafish model of Tuberous sclerosis complex

Mechanistic target of rapamycin complex 1 (mTORC1) is an integration hub for extracellular and intracellular signals necessary for brain development. Hyperactive mTORC1 is found in autism spectrum disorder (ASD) characterized by atypical reactivity to sensory stimuli, among other symptoms. In Tuberous sclerosis complex (TSC) inactivating mutations in the TSC1 or TSC2 genes result in hyperactivation of the mTORC1 pathway and ASD. Here, we show that lack of light preference of the TSC zebrafish model, tsc2 vu242/vu242 is caused by aberrant processing of light stimuli in the left dorsal habenula and tsc2 vu242/vu242 fish have impaired function of the left dorsal habenula, in which neurons exhibited higher activity and lacked habituation to the light stimuli. These characteristics were rescued by rapamycin. We thus discovered that hyperactive mTorC1 caused aberrant habenula function resulting in lack of light preference. Our results suggest that mTORC1 hyperactivity contributes to atypical reactivity to sensory stimuli in ASD.

Shy and Bold Fish Have the Same Preference for Light Color Selection.

Personality, which matters for animal welfare, demonstrates behavioral differences. Light is one of the most important factors in aquaculture. However, how fish personality affects light color selection is unclear. In this study, we tested the personality of yellow catfish Pelteobagrus fulvidraco juveniles and then quantified the selective behaviors of different personalities under six light colors: violet (410-420 nm), yellow (580-590 nm), green (550-560 nm), red (620-630 nm), blue (470-480 nm), and white. The results showed that juveniles preferred the yellow and green light over the other colors of light, probably due to different reasons. The average cumulative dwell time in yellow (32.81 ± 5.22%), green (21.81 ± 3.58%), and red (26.36 ± 4.89%) lights was significantly longer than the other light colors, and the average visit frequency in green light (32.00 ± 4.93%) was the most. Juveniles had the longest total moved distance in green light. Moreover, the results demonstrated that shy and bold individuals had the same preference for the green light. Bold individuals could find the preferred light colors rapidly and make quick decisions for light color selection. After identifying the preferred light colors, bold individuals reduced the frequency of exploration. This study provides a theoretical basis for the welfare of juvenile yellow catfish in aquaculture.

Evaluation of the effects of blue-enriched white light on cognitive performance, arousal, and overall appreciation of lighting.

Light's non-visual effects on the biological clock, cognitive performance, alertness, and mental health are getting more recognized. These are primarily driven by blue light, which triggers specific retinal cells containing melanopsin. Traditionally, research on light has relied on correlated color temperature (CCT) as a metric of its biological influence, given that bluer light corresponds to higher Kelvin values. However, CCT proves to be an inadequate proxy of light's biological effects. A more precise metric is melanopic Equivalent Daylight Illuminance (mel-EDI), which aligns with melanopsin spectrum. Studies have reported positive cognitive impacts of blue-enriched white light. It's unclear if the mixed results are due to different mel-EDI levels since this factor wasn't assessed. Given recent recommendations from experts to aim for at least 250 mel-EDI exposure daily for cognitive benefits, our aim was to assess if a 50-minute exposure to LED light with 250 mel-EDI could enhance concentration and alertness, without affecting visual performance or comfort compared to conventional lighting producing around 150 mel-EDI. To ensure mel-EDI's impact, photopic lux levels were kept constant across conditions. Conditions were counterbalanced, parameters included subjective sleepiness (KSS; Karolinska Sleepiness Scale), concentration (d2-R test), visual performance (FrACT; Freiburg Visual Acuity and Contrast Test), general appreciation (VAS; Visual Analogous Scale), preferences and comfort (modified OLS; Office Lighting Survey). The experimental light significantly reduced sleepiness (p = 0.03, Cohen's d = 0.42) and also decreased contrast sensitivity (p = 0.01, Cohen's d = 0.50). The conventional light was found to be more comfortable (p = 0.002, Cohen's d = 0.62), cheerful (p = 0.02, Cohen's d = 0.46) and pleasant (p = 0.005, Cohen's d = 0.55) while the experimental light was perceived as brighter (p = 0.004, Cohen's d = 0.58) and tended to be more stimulating (p = 0.10). Notably, there was a preference for conventional lighting (p = 0.004, Cohen's d=0.56) and concentration was equally improved in both conditions. Despite the lack of further improvement in concentration from exposure to blue-enriched light, given the observed benefits in terms of vigilance, further research over an extended period would be justified. These findings could subsequently motivate cognitive optimization through lighting for workers that would benefit from artificial lighting such as in northern regions.

Then the Lord said, 'Let there be natural light': The naturalness preference in Tibetan Buddhists’ evaluations of light

The naturalness preference refers to the tendency of individuals to perceive natural items as inherently superior, healthier, or more desirable compared to artificial or synthetic alternatives. Previous research has provided evidence that this cognitive bias is also operative in people's appraisal of light. Here, we took advantage of a testbed in Tibetan areas to examine the hypothesis that religious work may moderate individuals' assessment of different light sources. Drawing upon the exclusive utilization of daylight in the printing practices of the Buddhists at the Dege Sutra-Printing House, we postulated that they would exhibit a stronger preference for natural light compared to their fellow Buddhists. Consistent with our hypothesis, Study 1 found that printers demonstrated a heightened inclination towards natural light compared to other Tibetan Buddhists, despite their shared commitment to the religion. In a field study (Study 2), printers exhibited a greater propensity to choose a decoration scheme featuring natural light resources when compared to other Tibetan Buddhists. Across both studies, our findings indicated that perceptions of the morality and sacredness of light explained the differences between groups. Together, these findings highlight the important role of religious work when examining phenomena related to the evaluation of natural and artificial elements.

Enhanced Visual Performance for In–Vehicle Reading Task Evaluated by Preferences, Emotions and Sustained Attention

The proliferation of electric and hybrid vehicles has made it possible for people to read and work in a stationary vehicle for extended periods. However, the current commonly used in–vehicle lighting design is still centered around driving and driving safety. Following recommendations from the literature, a neutral white color band (4000 K–5000 K) with 50–100 lx at the vehicle table area is favored. Whether this lighting environment can meet the needs to enhance the reading performance in a modern vehicle was investigated in this presented study. Therefore, in total, 12 lighting settings were designed based on combinations of four illuminance levels (50 lx, 100 lx, 150 lx and 200 lx) and three correlated color temperatures (3000 K, 4000 K and 5000 K); we recruited 19 subjects (12 females, 7 males) and let study participants evaluate each condition based on electronic and paper reading. Next, subjective preferences, positive and negative emotions, feeling of fatigue and sustained attention were tested. We found that higher illuminance and higher CCT (Correlated Color Temperature) can significantly improve the performance of in–vehicle readers in most aspects following Kruithof’s law (p < 0.05). Among them, we recommend the combination of 150 lx and 4000 K as the light parameters for in–vehicle reading as a new development guideline. In addition, we also discovered the inconsistency of people’s lighting preferences between in–vehicle spaces and conventional spaces. For indoor lighting, illuminance values up to 1000 lx are still favored. For an in–vehicle function, starting with 200 lx, the preference level and reading performance already declined. In comparison between electronic and paper reading, both were similarly evaluated. These results show that a neutral white light color should be chosen with a horizontal illuminance of maximal 150 lx for a reading light function independent of the reading device. Interdisciplinarily speaking, our findings can be applied in similar small spaces or transportation modes with gentle acceleration and deceleration such as small space hotel rooms, trains, airplanes or ships.

Pathologists light level preferences using the microscope—study to guide digital pathology display use

BackgroundCurrently, there is a paucity of guidelines relating to displays used for digital pathology making procurement decisions, and optimal display configuration, challenging.Experience suggests pathologists have personal preferences for brightness when using a conventional microscope which we hypothesized could be used as a predictor for display setup. MethodsWe conducted an online survey across six NHS hospitals, totalling 108 practicing pathologists, to capture brightness adjustment habits on both microscopes and displays.A convenience subsample of respondents was then invited to take part in a practical task to determine microscope brightness and display luminance preferences, in the normal working environment. A novel adaptation for a lightmeter was developed to directly measure the light output from the microscope eyepiece. ResultsThe survey (response rate 59% n=64) indicates 81% of respondents adjust the brightness on their microscope. In comparison, only 11% report adjusting their digital display. Display adjustments were more likely to be for visual comfort and ambient light compensation rather than for tissue factors, common for microscope adjustments. Part of this discrepancy relates to lack of knowledge of how to adjust displays and lack of guidance on whether this is safe; But, 66% felt that the ability to adjust the light on the display was important.Twenty consultants took part in the practical brightness assessment. Light preferences on the microscope showed no correlation with display preferences, except where a pathologist has a markedly brighter microscope light preference. All of the preferences in this cohort were for a display luminance of <500 cd/m2, with 90% preferring 350 cd/m2 or less. There was no correlation between these preferences and the ambient lighting in the room. ConclusionsWe conclude that microscope preferences can only be used to predict display luminance requirements where the microscope is being used at very high brightness levels. A display capable of a brightness of 500 cd/m2 should be suitable for almost all pathologists with 300 cd/m2 suitable for the majority. Although display luminance is not frequently changed by users, the ability to do so was felt to be important by the majority of respondents.Further work needs to be undertaken to establish the relationship between diagnostic performance, luminance preferences, and ambient lighting levels.

Blue pill or red pill? Green, thanks. Behavioural test on coloured light preference in the Calabrian Alpine newt to increase the capture rate

Abstract To improve monitoring techniques, we investigated the colour vision of the Calabrian Alpine newt (Ichthyosaura alpestris inexpectata). We conducted controlled behavioural experiments on male and female newts to explore their response to artificial coloured light sources in the dark. We used green, blue, and orange glow sticks. Observations indicated that both sexes strongly preferred green glow sticks, which were selected in almost 50% of the trials Additionally, newts exhibited markedly swifter reactions to green light. The attraction to green glow sticks may be due to the biofluorescence within the green wavelength spectrum in this newt. This glowing ability, which resembles the green glow stick’s glow, could be beneficial in low-light conditions to locate other newts. Our results show that the behavioural preferences towards a particular light source can significantly enhance the success of capturing newts during population monitoring and conservation efforts for this rare and threatened taxon.

Color preferences among selected adults in Ghana

This paper presents a study on color preferences among a sample of Ghanaian adults. Two surveys were conducted, with a total of 143 participants (50 in Survey 1, and 93 in Survey 2). The participants completed both printed and digital questionnaires to gather data on their color preferences. The results showed that blue was the most preferred color by both males and females in general, but not for specific items. In survey 2, a chi-square test on categorical variables revealed a significant relationship between gender and preference for light, dark, or bright colors (p=0.025), as well as gender and number of preferred colors per personal item (p=0.02). However, no significant relationships were found between gender and change of colors from childhood (p=0.73), gender and number of preferred colors (p=0.204), gender and most preferred colors (p=0.216), age, and the number of preferred colors (p=0.19). Interestingly, 66.3% of the participants in Survey 2 indicated that their preferred colors were based on innate attraction, regardless of whether their color preferences had changed or remained the same since childhood. Overall, blue and red were the most preferred colors, with a score of 34.4%. These findings provide valuable insights for design practitioners and communicators and offer a basis for future research on color preferences among Ghanaians.

Uniform vs. uneven lighting: Accommodation of multiple users’ preferences in study rooms

Uniform lighting in public spaces like study rooms in libraries, is still a common practice. However, uniformly lit spaces are unable to simultaneously meet the needs of multiple users and can create dull environments. The objective of this research is to analyze users’ behavior under different lighting conditions in study rooms and investigate whether alternative lighting designs, which step away from uniformity, could be more beneficial than uniform lighting, from a human performance and well-being perspective. A uniformly lit study room in the library of KTH was chosen as the main case study of this investigation and was thoroughly analyzed and evaluated through qualitative and quantitative research. Under the initial hypothesis that the lighting in this study room does not meet its users’ needs and fails to create an inspiring and comfortable environment, three additional study rooms in different Swedish libraries were comparatively analyzed through observations, interviews, and questionnaires, so as to better understand individual users’ needs and lighting preferences in study rooms. The research revealed the existence of various types of users with different personal preferences regarding lighting in order to feel comfortable and alert. A new conceptual lighting proposal is presented for the study room in KTH library, following an uneven lighting approach that utilizes different lighting zones to accommodate individual needs and affect the sense of comfort, alertness, and ultimately, the well-being of multiple types of users.

Effects of illuminance and correlated color temperature on emotional responses and lighting adjustment behaviors

This article presents a novel approach to assessing human reactions to indoor artificial lighting and lighting adjustment behavior. Participants (n = 27) were each exposed to 17 different lighting conditions via selected combinations of seven illuminance levels and seven different correlated color temperatures (CCTs) in a virtual office environment. We collected data about emotional valence, arousal, adjusted values, and adjustment uncertainty (via the number of button presses) in each lighting condition. We also considered potential gender effects in the responses to the lighting. The study confirmed the presence of “anchor effects,” in which starting conditions significantly impacted subsequent preferences and adjustment behavior. After multiple randomized trials, we also found that lighting preferences shifted toward reduced illuminance. Moreover, women were found to have a lower preference for illumination levels and correlated color temperature than men. A greater Adjustment Uncertainty for illumination was associated with lower illumination values (<290 lx), while this was peaking at mid-range levels for CCT (3500 K–5500 K). The variety of behavioral response profiles we found in lighting adjustment, along with the likely impact of gender and other demographic variables, highlights the importance of customization options in lighting design for higher indoor environmental quality. This research supports architects and engineers in creating lighting designs attuned to occupants' emotions, preferences, and adjustment behaviors while emphasizing the benefits of using VR simulations in the AEC industry to assess lighting design impacts on users.

A13 MICROBIOTA FROM PATIENTS WITH INFLAMMATORY BOWEL DISEASE (IBD) INDUCE ALTERED BEHAVIOUR AND VISCERAL HYPERSENSITIVITY IN MICROBIOTA-HUMANIZED MICE

Abstract Background IBD is characterized by relapsing episodes of tissue-damaging inflammation in the gastrointestinal tract. Abdominal pain is common in IBD and often persists in the absence of overt inflammation. The treatment has limited efficacy, in part due to our partial understanding of its pathophysiology, and thus commonly leads to dependency on opioids. Moreover, patients with IBD are more likely to develop psychiatric comorbidities (anxiety and depression), further impairing the disease course and quality of life. The gut microbiota has been shown to modulate pain, mood, and anxiety. Gut bacterial composition and function are altered in patients with IBD. However, whether IBD microbiota affects pain perception and emotional behaviour is unknown. Aims To determine whether microbiota from patients with IBD contributes to visceral hypersensitivity and behavioural abnormalities in a microbiota-humanized mouse model. Methods Adult germ-free C57BL/6 mice (n=65) of both sexes were colonized with fecal microbiota from 7 patients with IBD (Crohn’s Disease n=5, Ulcerative Colitis n=2) and 3 healthy controls (HC). Mice were fed with a human-like (Western) diet. Behavioural tests (light preference, open field, and tail suspension tests) were employed to assess anxiety- and depression-like behaviour. Visceral sensitivity was assessed by measuring visceromotor responses to colorectal distension. Results Compared to mice with HC microbiota, mice with IBD microbiota had reduced body weight gain. However, no differences in colon length were found, suggesting that IBD microbiota did not induce overt colonic inflammation. Mice with IBD microbiota displayed a reduced preference for the light chamber and increased immobility in the tail suspension test compared to HC mice, suggestive of anxiety- and depression-like behaviour, respectively. Importantly, no differences in overall locomotion were observed, thus ruling out sickness-like behaviour. When subjected to colorectal distension, mice with IBD microbiota had an overall higher visceromotor response (area under the curve) compared to HC mice. Furthermore, they displayed increased responses to non-noxious stimuli (100 μL distension), suggestive of visceral allodynia. Conclusions Our data demonstrate that microbiota from patients with IBD negatively affects the gut-brain axis, by inducing changes in emotionality-related behaviour and triggering visceral hypersensitivity. Uncovering the microbial products and molecular mechanisms underlying these abnormalities will guide the development of novel microbiota-based therapies for patients with IBD. Funding Agencies CCC, CIHRCrohn's and Colitis Foundation (USA)

Unusual OCT findings in a patient with CABP4-associated cone–rod synaptic disorder

PurposeBi-allelic variants in CABP4 are associated with congenital cone–rod synaptic disorder, which has also been classified, electrophysiologically, as incomplete congenital stationary night blindness (iCSNB). We describe clinical findings in a patient who demonstrated an unusual macular optical coherence tomography (OCT) phenotype, not previously reported in this condition.MethodsOur patient underwent multimodal retinal imaging, international standard full-field ERG testing and whole genome sequencing.ResultsThe patient was a 60-year-old woman with non-progressive visual impairment since birth, nystagmus and preference for dim lighting. Clinical fundus examination was unremarkable. OCT imaging revealed a hypo-reflective zone under an elevated fovea in both eyes. ERGs showed an electronegative DA10 response, with severely abnormal light-adapted responses. Whole genome sequencing revealed homozygosity for a known pathogenic variant in CABP4. No variants were found in other genes that could explain the patient’s phenotype.ConclusionsOCT findings of foveal elevation and an underlying hypo-reflective zone are novel in this condition. Whilst the clinical history was similar to achromatopsia and other cone dysfunction syndromes, ERG findings suggested disease associated with CACNA1F or CABP4. As CACNA1F is X-linked, CABP4 was more likely, and confirmed on genetic testing. The patient saw better in dim light, confirming that night blindness is not a feature of CABP4-associated disease. Our case highlights the value of ERGs in discriminating between causes of cone dysfunction, and extends the range of retinal imaging phenotypes reported in this disorder.

Lighting preferences of Iberian sausages for Spanish observers

We report results of a visual experiment performed by 20 adult Spanish observers using calibrated images of 18 samples of sliced Iberian sausages under 15 illuminations, including 8 illuminants proposed by the International Commission on Illumination (CIE) and 7 light sources found in meat sections of supermarkets in Spain and Japan. Visual results from the pair comparison and magnitude estimation psychophysical methods used in our experiment showed a high correlation (Pearson’s linear correlation coefficient r = 0.915). Illumination strongly influenced color preferences of sliced Iberian sausages. For example, using the magnitude estimation method, the average lighting preferences changed about 2.8/10 for the 15 illuminations tested. There were no statistically significant differences between lighting preferences for different kind of sausages. Exploring quality indices of white lights, we found that the correlated color temperature and gamut area index (Color Res. Appl. 33, 192-202, 2008) provided the highest linear correlations with visual preferences in our current experiment. Lights with correlated color temperatures below 3000 K or gamut area indices below 70 were not preferred. The CIE general color rendering and color fidelity indices provided poor predictions of visual preferences in our current experiment.

Tracking the real-time behavior of Hemimysis anomala’s winter swarms using acoustic camera

Tracking the behavior of invasive alien species (IAS) is challenging due to logistical constraints that hinder high frequency surveys. Real-time automated recorders offer a promising solution, but their feasibility needs testing and validation. The acoustic camera is an efficient method to obtain real-time records of the behavior of Hemimysis anomala, a mysid that has invaded a variety of aquatic ecosystems. This approach is also a valuable tool for high-quality video recordings of mysid swarms in shallow habitats. The feasibility of this device to record the continuous behavior, including exit and entry (hereafter referred to as emergence and homing) from a shelter over a diel cycle was validated. Emergence consistently correlated with the onset of civil twilight, while homing displayed more intricate temporal trends. Homing events were longer than emergence events, but both were significantly influenced by light conditions. The termination of emergence was concomitant to the onset of the light preference as already shown by past studies. However, homing showed an earlier onset before light conditions exceeded the preference values, possibly due to inter-individual variability and/or information sharing in swarm behavior. The survey also captured the collapse in the targets number detected by the end of March, underlining the termination of the winter swarm. Furthermore, we demonstrated the importance of high-frequency temporal resolution, with a sampling frequency of at least 10-min, to accurately capture the swarm behavior. Overall, we provide original new insights characterizing H. anomala ecology and encourage the development of real-time automated recorders to track the behavior of IAS.

Are LED lights driving the massive nuptial flight swarm of the tramp ant Technomyrmex albipes?

AbstractWhereas most economic and ecological impacts of tramp ant species stem in large part from numerical dominance and exacerbated aggressiveness of workers, those imposed by alate (winged) ants have been rarely described. In the present study, we report an unprecedented massive alate swarming (i.e., mating flight) event in southern Taiwan by a tramp ant species, Technomyrmex albipes (Smith) (Hymenoptera: Formicidae), that triggers immediate pest management responses, and examine factor(s) that potentially contribute to the remarkably high number of alates. We monitored the seasonal activities of T. albipes workers and phenology of alate swarming, attempting to link the worker foraging dynamics with swarm ontogeny. As it was argued that recent streetlight fixtures converted from high‐pressure sodium to light‐emitting diode (LED) may serve as a major cause of the massive swarming, alates' light color preference was investigated. Sex ratio of trapped alates was also assessed to test whether sex‐specific light preference exists in T. albipes. We showed that foraging intensity of workers increased in the spring, peaked in May, and was followed by the nuptial flight season that began in August and lasted for 4 months. The phenological pattern is consistent with the colony dynamics in many other ant species. Although the two light preference experiments did not yield the same results, T. albipes alates overall preferred lights with shorter wavelengths in the active trapping, partially supporting the argument of white LED streetlights contributing to the massive flight. The sex ratio of trapped alates was overall female‐biased, suggesting female alates are disproportionally produced and/or more sensitive toward lights.

Beyond taxonomic diversity patterns - investigating how α and β components of macrophyte functional diversity respond to environmental gradients in lotic ecosystems of Greece.

In addition to quantifying the taxonomic diversity of aquatic communities, understanding the patterns of alpha functional diversity (α-diversity) and exploring changes in functional dissimilarity (β-diversity) can improve our understanding on how ecosystems respond to environmental changes. In this study, we quantified functional alpha (α) and beta (β) diversity of macrophytic assemblages from river sites in Greece and then, examined relationships with water quality parameters and hydromorphological factors. We assigned 6 traits (Ellenberg nutrients indicator, Ellenberg light indicator, growth form, leaf size, leaf type, fruit size) to a total of 36 hydrophyte species and calculated three indices of functional diversity (functional richness, functional dispersion and functional evenness). We also estimated the total β-functional diversity and its' main components, turnover and nestedness. To assess the effects of water quality (including physical and chemical variables) we used Generalized Additive Models (GAM) for alpha functional diversity indices and Generalized Dissimilarity Models (GDM) for beta functional diversity. We performed Kruskal-Wallis tests and permutational multivariate analysis of variance (PERMANOVA) to search for significant variations of α- and β-diversity among the hydromorphological factors. Our results showed that macrophyte growth form and light preference were important trait characteristics that explained a large share of the total variance of functional composition. We also found relatively low taxonomic and functional richness, whereas taxonomic and functional dissimilarity were mostly attributed to species turnover, which expresses the changes in taxonomic and functional composition. We found significant relationships between functional dispersion and functional evenness with pH and oxygen saturation, whereas functional dissimilarity was driven only by geographic distance, although the GDM explained a small portion of the total variance. Functional richness, dispersion and evenness were significantly higher at systems with fine substrates and deep waters with low or high flow compared to systems with coarser substrates and riffle habitats. We also found significant variation in functional dissimilarity among the hydromorphological factors, although much of the total variance remained unexplained. Overall, our study highlights the importance of considering the functional diversity of aquatic plant assemblages within the frame of freshwater monitoring and conservation plans.