Search Results (18)

Predation risk influences how animals approach predictable food sources where ambush predators may be present. In parids, chick-a-dee calls are used in a wide variety of contexts related to social cohesion and are well known as mobbing signals. Here, we examined whether they are also produced in the absence of visible predators in contexts in which predation risk may nevertheless be latent or uncertain. We tested whether chick-a-dee calls emitted by Willow Tits (Poecile montanus) during feeder approach exhibit acoustic and recruitment characteristics comparable to mobbing calls elicited by predator models. The study included repeated observations of 44 individuals across 11 flocks, enabling within-individual comparisons across habitat contexts. We analyzed call structure, calling duration, and recruitment latency in relation to habitat visibility and dominance status. Calls produced during the feeder approach showed overlapping structural features with mobbing calls and were associated with the recruitment of flock members, particularly in dense habitat. Mixed-effects models confirmed significant effects of habitat structure, predator presentation, and social rank on calling behavior and recruitment dynamics. These patterns are consistent with mobbing-like signaling under conditions of uncertain predation risk. Because predator presence and detection outcomes were not directly measured, our findings provide behavioral evidence compatible with proactive signaling rather than functional confirmation of predator probing. Full article

Behavioral individuality, often termed animal personality, reflects consistent patterns of behavioral variability across individuals. In fruit flies (Drosophila melanogaster), pharmacological and dietary manipulations affecting neuromodulatory systems have been shown to alter behavior, but their effects on behavioral predictability remain incompletely understood. Here, we investigated whether developmental dietary exposure to tryptophan (a serotonin precursor) or escitalopram (a selective serotonin reuptake inhibitor, SSRI) is associated with changes in lateralized turning behavior. Flies were reared from larval stages on supplemented media and tested in a Y-maze assay to assess movement predictability. Flies exposed to escitalopram displayed significantly reduced behavioral variability compared to controls, indicated by a lower median absolute deviation (MAD) of turning behavior, whereas tryptophan supplementation did not significantly affect variability. Because both compounds were tested at a single dietary dose and serotonergic activity was not directly measured, these findings should be interpreted as dose-specific behavioral effects rather than evidence of altered serotonergic tone or mechanism. Our results demonstrate that chronic developmental exposure to escitalopram is associated with increased behavioral predictability in fruit flies, highlighting the utility of high-throughput behavioral assays for detecting subtle pharmacologically induced changes in individual variability. Future studies incorporating dose–response designs and physiological validation will be required to establish underlying mechanisms. Full article

Phototaxis, the movement toward or away from light, is a fundamental behavior with ecological and evolutionary relevance. In Drosophila melanogaster, phototactic choice shows individual variability and has been linked to serotonergic signaling. Using a high-throughput FlyVac assay to test single flies in parallel, we reared w¹¹¹⁸ flies on (1) standard food (Control), (2) aMW (a serotonin-synthesis inhibitor), (3) 5-HTP (a serotonin precursor), or (4) escitalopram (a selective serotonin reuptake inhibitor, SSRI). Light-choice probability (LCP) did not differ between Control and aMW. LCP was lower in 5-HTP and escitalopram than in Control and aMW, and lower with escitalopram than with 5-HTP. Between-fly variability (MAD_n) differed across treatments: escitalopram exhibited higher dispersion than Control and aMW, whereas 5-HTP did not differ reliably from Control. These findings support the hypothesis that serotonin modulates behavioral predictability and mean choice bias; variability effects were compound-specific (escitalopram modestly increased MAD_n, whereas 5-HTP did not differ from Control). Given the rising costs and ethical constraints of vertebrate models, our results highlight Drosophila and FlyVac as a powerful, cost-effective system for investigating SSRI effects on decision phenotypes. Full article

Antipredator behavior can vary consistently among individuals, yet links between proactive nest defense and passive fear strategies are rarely quantified in the wild. We tested whether hissing, a conspicuous, snake-like display at the nest, predicts tonic immobility (TI) and breeding success in female Great Tits (Parus major). In pine forests in southeastern Latvia (2023–2024), we presented a taxidermic Great Spotted Woodpecker (Dendrocopos major) at nest-box entrances during incubation and scored whether females hissed and how many calls they produced. The same females were later assayed for TI by brief supine restraint when nestlings were 3–4 days old. Of 141 incubating females, 105 (74.5%) hissed. TI duration differed sharply between groups: non-hissing females showed significantly longer TI than hissing females. Nest failure was significantly lower in hissing than non-hissing female nests. These results reveal a strong negative association between proactive defense and passive fearfulness, and they show that hissing can translate into higher reproductive success in a Woodpecker-dominated predator environment. We conclude that defense strategies covary within individuals along a personality axis and that predator community composition may shape selection on these strategies. Full article

When selecting a habitat, it is optimal for organisms to choose one that maximizes reproductive success through access to high-quality resources, particularly in species that engage in parental care. However, organisms may inadvertently select a habitat for breeding that would initially appear preferential and undamaged, but may, in reality, be detrimental to parent and/or offspring fitness. In this study, we tested whether migratory European Pied Flycatchers (Ficedula hypoleuca) nesting in forest patches affected by outbreaks of the great web-spinning sawfly (Acantholyda posticalis) experienced fitness reductions indicative of an ecological trap, compared to those nesting in unaffected forest patches. After installing nest boxes to attract breeding pairs and potentially combat the outbreak, we found that Flycatchers inhabiting areas with sawfly outbreaks had similar clutch sizes to pairs breeding in unaffected forest patches. Contrarily, the fledgling number and body condition were significantly lower for those nesting in the damaged forests. In providing nest boxes for migrating Flycatcher pairs in forest patches that were subsequently impacted by a pest insect outbreak, an ecological trap arose for those pairs choosing to nest in what appeared to be an unaffected forest at first. Given the inability of breeding pairs to distinguish habitat quality on initial inspection, we suggest that nest boxes be used with caution in areas with unfavorable habitat conditions when attracting migratory birds, given the trends of their declining global numbers. Full article

In end-stage heart failure, which is characterized by persistent or progressive ventricular dysfunction despite optimal medical therapy, a left ventricular assist device (LVAD) can be beneficial. Congestive heart failure provokes inflammatory and prothrombotic activation. The aim of this study was to evaluate the serum concentration of citrullinated histone 3 (CH3) representing neutrophil extracellular trap (NET) formation in patients referred for LVAD implantation. There were 10 patients with a median age of 61 (57–65) years enrolled in a prospective single-center analysis who underwent LVAD implantation. The CH3 plasma concentration was measured preoperatively and on the 1st and 7th postoperative days, followed by control measurements on the median (Q1–3) 88th (49–143) day. The preoperative CH3 concentration strongly correlated with brain natriuretic peptide (r = 0.879, p < 0.001). Significant differences in CH3 serum concentration were observed between pre- and postoperative measurements, including an increase on the first postoperative day (p < 0.001), as well as a decrease on the seventh day (p = 0.016) and in follow-up (p < 0.001). CH3 concentration, as a marker of NET formation, decreases after LVAD implantation. Full article

Background: Multiple risk factors for coronary artery disease have been identified without answering one of the leading questions related to the extent of the involvement of the epicardial arteries. Trace elements are involved in various stages of atherosclerotic lesion formation and may play a significant role in the advancement of coronary artery disease. Methods: A total of 157 (92 (59%) men and 65 (41%) women) patients with a median age of 71 (65–75) years presenting with chronic coronary syndrome were enrolled in the prospective single-center analysis. The coronary angiography results were compared with the concentration of trace elements in scalp hair. Results: Through Spearman analysis, a positive correlation between the number of diseased coronary arteries and hair trace element concentration was found for sodium (r = 0.198, p = 0.013), vanadium (r = 0.164, p = 0.040), chromium (r = 0.242, p = 0.002), and nickel (r = 0.176, p = 0.026). A negative relationship was noted between magnesium (r = −0.237, p = 0.003) and calcium (r = −0.217, p = 0.007) and the extent of epicardial lesions. Conclusions: Scalp hair trace element analysis indicates the possible modulatory role of trace elements in advancing coronary artery disease. Since a significant correlation with one- and two-vessel but not with three-vessel disease was noted, it might be considered an “all or nothing” phenomenon. A positive correlation between the number of diseased coronary arteries and sodium, vanadium, chromium, and nickel and an inverse correlation with magnesium and calcium were noted. The presented analysis is hypothesis-generating, and further studies are necessary to corroborate the results from a clinical perspective. Full article

Beef is a perishable food that can be naturally preserved using antimicrobial chemicals in a procedure known as biopreservation. Probiotic bacteria, or bacteria with the ability to create antimicrobial metabolites, are known as lactic acid bacteria. Fermented foods such as dadih, or fermented buffalo milk, from West Sumatra, Indonesia, contain lactic acid bacteria. This study aims to explore the existence of probiotic lactic acid bacteria in dadih and the effectiveness of utilizing lactic acid bacteria metabolites as biopreservatives in beef for nine days at 4 °C. The DK1 strain of lactic acid bacteria showed the most antibacterial metabolite activity against Salmonella sp. (11.5 mm) and Escherichia coli (13 mm) among the three isolates examined. Probiotic characteristics set the DK1 isolate apart; resistance test results showed over 10⁶ CFU/mL, pH 2–4, a temperature range of 25 °C to 45 °C, and 0.3% bile salt. DK1 isolates tested positive for auto-aggregation 89.2% of the time. The co-aggregation test results for Salmonella sp. and E. coli reveal 46.9% and 53.1%, respectively. The findings of the bio preservation showed that, overall, treated beef contained fewer E. coli and other microorganisms than untreated meat. Furthermore, compared to control beef, metabolite-treated meat showed a shift in hue and a lower, more constant pH value. Full article

The optimal body mass hypothesis posits that the body reserves of wintering birds are balanced between the risk of starvation and predation. In this study, we tested whether the body mass of wintering Great Tits (Parus major) was higher under conditions of less predictable food resources. We compared body mass, body mass index, the speed at take-off, and apparent survival of Great Tit adult males wintering in small urban areas either near feeders providing permanent access to food for months or near feeders providing irregular access to food. Body mass and body mass index were greater, while take-off speed and apparent survival were lower, in birds wintering near permanent feeders than birds wintering near irregular feeders. Thus, urban birds, with their predictable access to high energy food, did not follow the fattening strategy predicted by the optimal body mass hypothesis. This study shows that regular excess amounts of high-energy food may affect urban birds’ physiological and behavioral strategies in a non-adaptive way. We recommend irregular feeding of wintering birds and the placing of feeders in places that are safe against attacking predators. Full article

The Mahānayaprakāśa of Śitikaṇṭha is an understudied text within Kashmir Śaivism, notable for its rich description of the inner structure of consciousness vis-à-vis the body and the natural world, and esotericization of Left-Handed Tantric Practice. Furthermore, it is also significant in its form; like the Buddhist dohākoṣas it consists of Apabhraṃśa verses with accompanying Sanskrit commentary. However, in the sporadic scholarship on this text it is consistently portrayed as an early attestation of “Old Kashmiri,” and siloed off into obscurity. This article demonstrates that these verses are definitively composed in Apabhraṃśa, and argues that they should be examined alongside their Buddhist counterparts, which also articulate a mystical cosmology of the sacred realm Uḍḍiyāna located within the body. Afterwards the fourth chapter of this text is translated and presented, in which the human body takes center stage as the pīṭha, the pilgrimage destination and practice space of Tantric ritual. Ultimately this article argues that within medieval Tantric traditions the Apabhraṃśa verse form served as a privileged vehicle of esoteric teachings, and that it commands a unique linguistic value by indexing mystical states of consciousness. Full article

Blood parasites are considered to have strong negative effects on host fitness. Negative fitness consequences may be associated with proximity to areas where blood parasite vectors reproduce. This study tested for relationships between haemosporidian infection prevalence, parasitemia, and fitness parameters of breeding Pied Flycatchers (Ficedula hypoleuca) at different distances from forest water bodies. Prevalence and parasitemias (the intensity of infection) of haemosporidians and vector abundance generally decreased with increasing distance from forest lakes, streams, and bogs. Fledgling numbers were lower, and their condition was worse in the vicinity of water bodies, compared with those located one kilometer away from lakes and streams. At the beginning of the breeding season, adult body mass was not related to distance to the nearest water body, whereas at the end of the breeding season body mass was significantly lower closer to water bodies. Forest areas around water bodies may represent ecological traps for Pied Flycatchers. Installing nest boxes in the vicinity of forest water bodies creates unintended ecological traps that may have conservation implications. Full article

Bumblebees are key pollinators in agricultural landscapes. However, little is known about how gut microbial communities respond to anthropogenic changes. We used commercially produced colonies of buff-tailed bumblebees (Bombus terrestris) placed in three habitats. Whole guts (midgut, hindgut, and rectum) of B. terrestris specimens were dissected from the body and analyzed using 16S phylogenetic community analysis. We observed significantly different bacterial community composition between the agricultural landscapes (apple orchards and oilseed rape (Brassica napus) fields) and forest meadows, whereas differences in gut communities between the orchards and oilseed rape fields were nonsignificant. Bee-specific bacterial genera such as Lactobacillus, Snodgrassella, and Gilliamella dominated gut communities of B. terrestris specimens. In contrast, the guts of B. terrestris from forest meadows were dominated by fructose-associated Fructobacillus spp. Bacterial communities of workers were the most diverse. At the same time, those of males and young queens were less diverse, possibly reflecting greater exposure to the colony’s inner environment compared to the environment outside the colony, as well as bumblebee age. Our results suggest that habitat quality, exposure to environmental microbes, nectar quality and accessibility, and land use significantly affect gut bacterial composition in B. terrestris. Full article

While COVID-19 infection and mortality rates are soaring in Western countries, Southeast Asian countries have successfully avoided the second wave of the SARS-CoV-2 pandemic despite high population density. We provide a biochemical hypothesis for the connection between low COVID-19 incidence, mortality rates, and high visceral adiposity in Southeast Asian populations. The SARS-CoV-2 virus uses angiotensin-converting enzyme 2 (ACE2) as a gateway into the human body. Although the highest expression levels of ACE2 are found in people’s visceral adipose tissue in Southeast Asia, this does not necessarily make them vulnerable to COVID-19. Hypothetically, high levels of visceral adiposity cause systemic inflammation, thus decreasing the ACE2 amount on the surface of both visceral adipocytes and alveolar epithelial type 2 cells in the lungs. Extra weight gained during the pandemic is expected to increase visceral adipose tissue in Southeast Asians, further decreasing the ACE2 pool. In contrast, weight gain can increase local inflammation in fat depots in Western people, leading to worse COVID-related outcomes. Because of the biological mechanisms associated with fat accumulation, inflammation, and their differential expression in Southeast Asian and Western populations, the second wave of the pandemic may be more severe in Western countries, while Southeast Asians may benefit from their higher visceral fat depots. Full article

Juvenile hormone has been suggested to be a potential mediator in the trade-off between mating and insects’ immunity. Studies on various insect taxons have found that juvenile hormone interferes with humoral and cellular immunity. Although this was shown experimentally, studies using highly virulent parasites or pathogens are lacking so far. In this study, we tested if juvenile hormone administration affected resistance against entomopathogenic fungi, Metarhizium robertsii, in the mealworm beetle, Tenebrio molitor. In previous studies with T. molitor, juvenile hormone has been found to reduce a major humoral immune effector-system (phenoloxidase) in both sexes and decrease the encapsulation response in males. Here, we found that juvenile hormone administration prolonged survival time after infection with M. robertsii in males but reduced survival time in females. This study indicates that the effects of juvenile hormone on insect immunity might be more complicated than previously considered. We also suggest that there might be a trade-off between specific and non-specific immunity since, in males, juvenile hormone enhances specific immunity but corrupts non-specific immunity. Our study highlights the importance of using real parasites and pathogens in immuno-ecological studies. Full article

Research Highlights: Studies on tree canopy dwelling species often require simple proxies of tree canopy volume estimated at a stand level. These include allometrically related tree crown parameters such as crown area and basal area, and canopy cover. Background and Objectives: In monoculture Scot’s pine and mixed pine/Norway spruce forest, we aimed to test the relationships between tree diameter at breast height (DBH) and tree crown volume at a tree level and between densitometer canopy closure estimates and tree crown volume at a stand level. Materials and Methods: The study was carried out in eastern Latvia (hemiboreal zone) in monoculture pine and mixed coniferous stands. On a subset of trees in 22 forest stands (88 100 m² plots), we determined the best regression model that described the relationship between tree DBH and crown volume for spruce and pine. Tree crown volume at a stand level was determined from the individual tree volume estimates calculated from these regression models. On a stand level, we also calculated regression models for densitometer closure estimates versus total crown volume for pine and mixed stands. Results: Linear mixed effects models showed significant relationships between DBH and crown volume for pine (R² = 0.63) and spruce (R² = 0.40), indicating that basal area could be used as a predictor of crown volume at a stand level. Variance explained by a regression model of canopy closure versus tree crown volume at a stand level was R² = 0.52. Conclusions: Tree basal area and crown closure can be used as proxies of tree crown volume at a stand scale in monoculture stands. In mixed stands estimates of crown volume based on basal area need to be calculated separately for each tree species, while canopy closure will provide an estimate of total crown volume. Full article