Search Results (27)

The ability of terrestrial isopods (Crustacea: Isopoda: Oniscidea) to protect themselves effectively from predation by birds has never been tested. They are equipped with glands producing chemical substances; moreover, some species show conspicuous coloration, which might suffice as an aposematic signal. We evaluated the palatability of isopods to birds. We tested the responses of Parus major captured in the wild (and thus possessing some experience with common native isopod species) to the following isopod species: Porcellio scaber (native, inconspicuous), Oniscus asellus (native, moderately conspicuous), Armadillo officinalis (non-native, moderately conspicuous), Armadillidium versicolor (native, conspicuous), and Armadillidium gestroi (non-native, conspicuous). We compared bird responses to isopods with reactions to the Blaptica dubia, an edible roach very similar to isopods in size and appearance. Isopods were better protected from bird attacks than roaches; however, their color pattern did not affect the level of protection. Birds were able to differentiate isopods from the roach; in experiments, where we presented isopod and roach individuals together, the birds hesitated longer in attacking and observed both prey items for a longer time. Non-native species either profited from the generalization of the protection of native isopods or from neophobia. Some isopods elicited significantly more discomfort behavior in birds, suggesting differences in the chemical protection among the tested species. Full article

The Carabidae family, or ground beetles, is a wide and ecologically significant group within the Coleoptera order, known for its role as natural predators of agricultural pests and as bioindicators of ecosystem health. These beetles employ a variety of behavioral, morphological, and chemical defense strategies to protect themselves from predators. These mechanisms include gregariousness, stridulation, regurgitation, and chemical defenses, such as the secretion of irritating compounds from specialized glands. The defensive strategies of carabids are classified into passive and active systems, each with varying energetic costs. Chemical substances (e.g., Formic acid, Methacrylic acid, Tiglic acid, Ethacrilic acid, Isovaleric acid, Salicylaldehyde, 1,4-Benzoquinone, Toluquinone, 13-2Kt tridecan-2-one, Undecane, Tridecane, Pentadecane, M-cresol) are particularly important, as they serve to deter predators and combat pathogens like bacteria and fungi. Ground beetles utilize both polar and non-polar compounds in their defense, all contributing to their ecological success. This review explores the array of defensive mechanisms in the Carabidae family, highlighting experimental studies, field observations, and reviews published over the last five decades. The aim is to provide a comprehensive understanding of how these strategies enhance the survival and fitness of carabid beetles in their natural environments. Full article

This study explores the external morphology of larva of Cricula trifenestrata Helfer at the fifth instar stage, focusing on sexual dimorphism, scoli, and fluorescence hair warts. The larva displays a black body adorned with varying shades of orange to crimson–red transverse stripes and small yellow dorsal spots. Longitudinal stripes with fluorescent warts are observed in the subspiracular region, accompanied by an overall coverage of long white hairs. These distinctive features, including scoli and fluorescence hair warts, serve as effective defense mechanisms against predators and parasitoids. The results enhance our understanding of C. trifenestrata Helfer larval biology, providing valuable insights for entomology and evolutionary biology. The identification of species-specific adaptations, particularly the presence of scoli and fluorescence hair warts, underscores their significance in shaping survival strategies and ecological interactions. Full article

Many toxic animals display bright colour patterns to warn predators about their toxicity. This sometimes leads other sympatric palatable organisms to evolve mimetic colour patterns to also evade predation. These mimics, however, are often imperfect, and it is unclear how much their colour patterns can vary away from the model before they become ineffective. In this study, we investigated how predation risk of the palatable Common Mormon butterfly (Papilio polytes) is affected by two alterations of its wing pattern that make it progressively more distinct from its model, the Common Rose (Pachliopta aristolochiae). We deployed butterfly paper models in the field, where all models displayed the same colours but had different patterns. In the first modification from the Wildtype pattern, we exchanged the position of the red and white colour patches but kept the overall pattern constant. In the second modification, we created an eyespot-like shape from the pre-existing pattern elements by moving their positions in the wing, altering the overall wing pattern. Both modifications increased attack risk from predators relative to Wildtype patterns, with the eyespot-like modification having the highest predation risk. Our results show that avian predators can distinguish between all three patterns tested, and that pattern is important in aposematic signals. Predators learn to avoid aposematic colours, not in isolation, but as part of specific patterns. Full article

An invasive spider from East Asia has established in the U.S. southeast (the “jorō spider,” Trichonephila clavata) and is rapidly expanding its range. Studies assessing the impact of this species are needed, including how expansive its diet is. An open question is whether monarch butterflies, Danaus plexippus, are a potential prey item for this spider, given that jorō spiders do not coexist with monarchs in their native range. Since monarch larvae feed on milkweed, they sequester cardiac glycosides into their adult tissues, rendering them unpalatable to many predators. At sites within northeast Georgia, we staged a series of trials (n = 61) where we tossed monarchs into jorō spider webs and, for comparison, performed similar trials with another aposematic species, gulf fritillary (Agraulis vanilla), and a palatable species, tiger swallowtail (Papilio glaucus). We recorded the outcome of the trials, which included whether the spider attacked or did not attack the prey. We also conducted a visual survey during the same fall season to look for evidence of jorō spiders consuming monarchs naturally. Our findings revealed that jorō spiders avoided eating monarchs; spiders only attacked monarchs 20% of the time, which was significantly less than the attack rates of similarly sized or larger butterflies: 86% for gulf fritillaries and 58% for tiger swallowtails. Some jorō spiders even removed monarchs from their webs. From our visual surveys of the surrounding area, we found no evidence of natural monarch consumption and, in general, butterflies made up only a fraction of the jorō spider diet. We conclude that jorō spiders appear to recognize monarch butterflies as being unpalatable, even without having a prior history with the species. This invokes questions about how these spiders can immediately recognize their unpalatability without touching the butterflies. Full article

Florivory, i.e., flower herbivory, of various types is common and can strongly reduce plant fitness. Flowers suffer two very different types of herbivory: (1) the classic herbivory of consuming tissues and (2) nectar theft. Unlike the non-reversibility of consumed tissues, nectar theft, while potentially reducing a plant’s fitness by lowering its attraction to pollinators, can, in various cases, be fixed quickly by the production of additional nectar. Therefore, various mechanisms to avoid or reduce florivory have evolved. Here, I focus on one of the flowers’ defensive mechanisms, aposematism, i.e., warning signaling to avoid or at least reduce herbivory via the repelling of herbivores. While plant aposematism of various types was almost ignored until the year 2000, it is a common anti-herbivory defense mechanism in many plant taxa, operating visually, olfactorily, and, in the case of nectar, via a bitter taste. Flower aposematism has received only very little focused attention as such, and many of the relevant publications that actually demonstrated herbivore repellence and avoidance learning following flower signaling did not refer to repellence as aposematism. Here, I review what is known concerning visual-, olfactory-, and nectar-taste-based flower aposematism, including some relevant cases of mimicry, and suggest some lines for future research. Full article

Snake venoms constitute a complex, rapidly evolving trait, whose composition varies between and within populations depending on geographical location, age and preys (diets). These factors have determined the adaptive evolution for predatory success and link venom heterogeneity with prey specificity. Moreover, understanding the evolutionary drivers of animal venoms has streamlined the biodiscovery of venom-derived compounds as drug candidates in biomedicine and biotechnology. The king cobra (Ophiophagus hannah; Cantor, 1836) is distributed in diverse habitats, forming independent populations, which confer differing scale markings, including between hatchlings and adults. Furthermore, king cobra venoms possess unique cytotoxic properties that are used as a defensive trait, but their toxins may also have utility as promising anticancer-agent candidates. However, the impact of geographical distribution and age on these potential venom applications has been typically neglected. In this study, we hypothesised that ontogenetic venom variation accompanies the morphological distinction between hatchlings and adults. We used non-transformed neonatal foreskin (NFF) fibroblasts to examine and compare the variability of venom cytotoxicity between adult captive breeding pairs from Malaysian and Chinese lineages, along with that of their progeny upon hatching. In parallel, we assessed the anticancer potential of these venoms in human-melanoma-patient-derived cells (MM96L). We found that in a geographical distribution and gender-independent manner, venoms from hatchlings were significantly less cytotoxic than those from adults (NFF; ~Log EC₅₀: 0.5–0.6 vs. 0.2–0.35 mg/mL). This is consistent with neonates occupying a semifossorial habitat, while adults inhabit more above-ground habitats and are therefore more conspicuous to potential predators. We also observed that Malaysian venoms exhibited a slightly higher cytotoxicity than those from the Chinese cobra cohorts (NFF; Log EC₅₀: 0.1–0.3 vs. 0.3–0.4 mg/mL), which is consistent with Malaysian king cobras being more strongly aposematically marked. These variations are therefore suggestive of differential anti-predator strategies associated with the occupation of distinct niches. However, all cobra venoms were similarly cytotoxic in both melanoma cells and fibroblasts, limiting their potential medical applications in their native forms. Full article

Moths are among the most diverse and abundant animals. They have evolved a suite of acoustic defenses, such as producing ultrasound to guard against predation by low-duty-cycle bats. Recently, we found that the ultrasonic clicks of several moth species can also help decrease the capture success of high-duty-cycle bats. We tested whether moth clicks could advertise moth toxicity and/or jam the echolocation calls of high-duty-cycle bats. We examined the acoustic response of a hawkmoth (Cechenena minor) and a tiger moth (Creatonotos transiens) to free-flying horseshoe bats, Rhinolophus osgoodi. C. minor and C. transiens produced anti-bat ultrasonic clicks with an average duty cycle of 22.3% and 4.9%, respectively. The clicks of C. minor overlapped spectrally with the echolocation calls of R. osgoodi. C. minor occasionally emitted clicks immediately after the end of bat feeding buzzes. The clicks of C. transiens did not overlap spectrally with the echolocation calls of R. osgoodi. More than half the click sequences of C. transiens were produced before the emergence of bat feeding buzzes and did not overlap temporally with the feeding buzzes. Moreover, we found that C. minor was palatable and C. transiens was unpalatable to R. osgoodi. These results suggest that C. minor might be capable of jamming R. osgoodi and might also use ultrasonic clicks as warning signals. The clicks of C. transiens probably function to advertise moth toxicity. This study highlights the diversity of moth anti-bat sounds and illustrates the potential mechanisms of moth acoustic defense against high-duty-cycle bats. Full article

The rise in global temperature also favors the multiplication of pests and pathogens, which calls into question global food security. Plants have developed special coping mechanisms since they are sessile and lack an immune system. These mechanisms use a variety of secondary metabolites as weapons to avoid obstacles, adapt to their changing environment, and survive in less-than-ideal circumstances. Plant secondary metabolites include phenolic compounds, alkaloids, glycosides, and terpenoids, which are stored in specialized structures such as latex, trichomes, resin ducts, etc. Secondary metabolites help the plants to be safe from biotic stressors, either by repelling them or attracting their enemies, or exerting toxic effects on them. Modern omics technologies enable the elucidation of the structural and functional properties of these metabolites along with their biosynthesis. A better understanding of the enzymatic regulations and molecular mechanisms aids in the exploitation of secondary metabolites in modern pest management approaches such as biopesticides and integrated pest management. The current review provides an overview of the major plant secondary metabolites that play significant roles in enhancing biotic stress tolerance. It examines their involvement in both indirect and direct defense mechanisms, as well as their storage within plant tissues. Additionally, this review explores the importance of metabolomics approaches in elucidating the significance of secondary metabolites in biotic stress tolerance. The application of metabolic engineering in breeding for biotic stress resistance is discussed, along with the exploitation of secondary metabolites for sustainable pest management. Full article

In this article, we propose to explore the chemical interaction between Pseudosphinx tetrio L. and Allamanda cathartica L. using different analytical methods, including an innovative electrochemical approach (called electrochemical ecology) and multivariate analysis, and we investigate the potential antimicrobial effects (antibacterial and antifungal activities) of this interaction in order to gain a better understanding of their specific interaction. The analytical study presents a similar chemical profile between the leaves of healthy and herbivorous A. cathartica and the excretions of the caterpillars. The similar analytical profile of the leaves of A. cathartica and the excretions of P. tetrio, and the difference with the caterpillar bodies, suggests a selective excretion of compounds by the caterpillar. The measured antimicrobial activities support the physicochemical tests. The natural products found selectively in the excretions (rather than in the body) could explain the ability of P. tetrio to feed on this toxic Apocynaceae species. Full article

Many insects display a cryptic color to avoid detection by predators that search for prey by sight. However, some species with chemicals that predators dislike may display a warning color (aposematism) to predators. The predators can learn easier that the species is unsuitable as prey if the color is more conspicuous. Therefore, it is assumed that the acquisition of the warning color requires not only unpalatability, but also exposure of the color to predators and the ability of predators to recognize and learn it unpalatable. In the moths of the subfamily Ennominae, almost all of genera produce uniformly brown or green pupae, but the pupae of the genus Cystidia have conspicuous coloration of yellow background and black spots. In this study, to clarify whether the color of these pupae is the warning color or not, we compared the coloration, pupation site, and palatability among the three species of this genus: C. couaggaria, C. truncangulata, and C. stratonice. Learning by the predators was also examined using lizards as a potential predator of the moths. The results showed that all three species were repelled (unpalatable) by the lizards, and that repeated providing of the pupae to the lizards decreased their willingness to prey on them (probably due to learning). Pupation sites of C. couaggaria and C. truncangulata were located on the surface of branches and leaves high above the ground, whereas C. stratonice pupated in the space of leaves spun with course silk at lower site above the ground. Thus, the conspicuous coloration of pupal Cystidia is considered to be a warning color, but the pupae of C. stratonice are more blackish than those of the most closely related C. truncangulata. The pupal color of C. stratonice is likely to have a dual meaning as cryptic and warning colors. The dark colored pupa may be inconspicuous when hidden within the leaf space, but once detected by the predators, the yellow color of the pupa may function as a warning color. Full article

Increasing evidence in the field of bioprospection fosters the necessity of studying poorly investigated poisonous marine invertebrates to expand knowledge on animal venom biology. Among marine annelids, amphinomid fireworms are notorious for their bearded trunk equipped with a powerful stinging capacity. Here, a methodological workflow based on analytical chemistry techniques (compound isolation followed by mass spectrometry and spectroscopy analyses) was applied to gain new insights, leading to the identification and structural elucidation of an array of natural products from Mediterranean specimens of Hermodice carunculata. Eight betaine-derived unprecedented compounds, named “carunculines”, were detected, bearing two terminal ammonium groups tri-and disubstituted at the Cα (A, B) and a series of different alkyl chains (I–VIII). The mixture of chemicals was found in all the body parts of H. carunculata, supporting a mechanism of action triggered by their vehiculation inside the dorsal chaetae, and subsequent injection when chaetae break off on contact. Preliminary investigations to understand adaptive features were also performed, showing a trend in carunculine abundance that fits into the evolutionary history of these worms. These findings shed light on the chemical ecology of amphinomids, giving reasons for the success of H. carunculata in benthic environments and providing promising novel metabolites for biotechnological implications. Full article

The elateroid family Lycidae is known for limited dispersal propensity and high species-level endemism. The red net-winged beetle, Dictyoptera aurora (Herbst, 1874), differs from all relatives by the range comprising almost the entire Holarctic region. Based on a five-marker phylogeny and 67 barcode entries (cox1-5′ mtDNA) from the whole range, we recovered two genetically distinct species within traditionally defined D. aurora and resurrected the name D. coccinata (Say, 1835) as the oldest available synonym for Nearctic populations. Yet, no reliable morphological trait distinguishes these species except for minute differences in the male genitalia. D. coccinata is a monophylum resulting from a single Miocene dispersal event, ~15.8 million years ago, and genetic divergence implies long-term isolation by the Bering Strait. Far East Asian and west European populations are also genetically distinct, although to a lower extent. Two independent colonization events established the Fennoscandian populations after the last glacial maximum. Besides intrinsic factors, the high morphological similarity might result from stabilizing selection for shared aposematic signals. The rapidly accumulating barcode data provide valuable information on the evolutionary history and the origins of regional faunas. Full article

As IoT devices’ adoption grows rapidly, security plays an important role in our daily lives. As part of the effort to counter these security threats in recent years, many IoT intrusion detection datasets were presented, such as TON_IoT, BoT-IoT, and Aposemat IoT-23. These datasets were used to build many machine learning-based IoT intrusion detection models. In this research, we present an explainable and efficient method for selecting the most effective universal features from IoT intrusion detection datasets that can help in producing highly-accurate and efficient machine learning-based intrusion detection systems. The proposed method was applied to TON_IoT, Aposemat IoT-23, and IoT-ID datasets and resulted in the selection of six universal network-flow features. The proposed method was tested and produced a high accuracy of 99.62% with a prediction time reduced by up to 70%. To provide better insight into the operation of the classifier, a Shapley additive explanation was used to explain the selected features and to prove the alignment of the explanation with current attack techniques. Full article

Degradation of biodiversity is one of the current problems of today, and scientists are increasingly concerned with identifying the key factors influencing people’s willingness to protect (WTP) wild organisms. Using a within-subject design, we investigated the influence of aposematic signals along with the presence or absence of flowers on perceived danger, attractiveness and WTP plants with lower secondary school students (mean age = 13 yrs) in Slovakia (n = 423). Aposematic plants received a higher dangerousness score (mean = 2.62 vs. 2.27), higher attractiveness score (mean = 3.45 vs. 3.32) and lower WTP plants than plants without aposematic signals (mean = 3.27 vs. 3.37). Interaction terms showed that males perceived the aposematic species as more dangerous than females and were more willing to protect species lacking aposematic signals. Females rated aposematic plants as more attractive than non-aposematic plants (mean = 3.82 vs. 3.0). The presence of flowers increased the perceived attractiveness of plants (mean = 3.75 vs. 3.02) and WTP plants (mean = 3.59 vs. 3.05) and decreased perceived dangerousness (mean = 2.70 vs. 2.20). Perceived attractiveness and WTP plants decreased with students’ age. Students with a higher interest in plants rated the attractiveness of the species more positively and were also more willing to protect them regardless of the presence of aposematic signals. We conclude that the presence of aposematic signals does not directly contribute to WTP plants, but conspicuous traits with high aesthetic value, such as flowers, positively enhance WTP in Slovak students. Full article