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Inducible defense is an important anti-insect strategy in plants. This study investigated whether larval feeding by Hyphantria cunea at low-density and high-density levels can initiate inducible defense responses in the low-fitness host plant Tilia amurensis on the 7th- and 21th-day post-feeding. The results revealed significant alterations in the nutrient composition (e.g., amino acids, soluble sugars, and total proteins) within T. amurensis, with notable decreases observed on the 7th-day post-feeding, followed by increases on the 21st day, respectively. Specifically, the low-density feeding group prompted significant increases in tannin, total phenols, and total flavonoids on the 7th day, whereas the high-density feeding group induced significant decreases in these compounds. Conversely, total alkaloid levels exhibited an inverse pattern, with lignin contents notably decreasing. By the 21st-day post-feeding, all secondary metabolites demonstrated significant increases. Expression analysis of flavonoid biosynthetic genes mirrors the changes observed in the total flavonoid content. Furthermore, larval feeding activates the α-linoleic acid metabolism pathway consistently across all time points. Subsequent generations of H. cunea larvae in low-density feeding and high-density feeding groups demonstrated decreased growth, along with downregulation of growth regulatory genes and key genes involved in energy metabolism, digestion, and detoxification. Notably, the expression of digestive gene LIP10 and detoxification genes GST18 and CARE14 exhibits adaptive regulation in response to T. amurensis’ inducible defense. Overall, larval feeding by H. cunea elicits a robust and enduring inducible defense response in T. amurensis, ultimately decreasing the fitness of the subsequent generations of H. cunea larvae on T. amabilis. [ABSTRACT FROM AUTHOR]

The article explores the impact of leaf mining on the chemical defense of a Late Triassic ginkgophyte plant using ATR-FTIR analysis. Leaf mining by insect larvae can lead to increased water and nutrient loss, reduced photosynthesis, and altered plant defenses. The study found that leaf mining induced chemical changes in both modern and fossil leaves, with evidence of plant defense responses to leaf mining detected through chemical analysis. The research sheds light on the co-evolutionary dynamics between plants and insects in ancient ecosystems and highlights the potential of chemical analysis in understanding plant defenses in deep time. [Extracted from the article]

Simple Summary: During routine feeding of crickets to laboratory imported fire ant colonies, it was observed that while most of the cricket tissues are used by the fire ants, only the hard outside shell or cuticle and the eggs are not utilized. Interestingly, the eggs are removed from the nest and deposited on refuse piles created by the fire ants. Why waste a highly nutritious food source, such as cricket eggs? It was found through several experimental trials and chemical analyses that the surface of the cricket egg has a chemical profile consisting mainly of fatty acids, like that found on dead fire ants. It thus elicits what is known as necrophoric behavior, where chemical cues on the surface of the ants elicit a behavior in which the dead ants are removed from the colony and deposited in refuse piles. Possible reasons for such similar surface compositions between fire ants and cricket eggs are discussed. The house cricket, Acheta domesticus (Linnaeus), is often used as a food source for the maintenance of imported fire ants under laboratory rearing. It was found that both red imported fire ants, Solenopsis invicta Buren, and black imported fire ants, S. richteri Forel, consumed most of the soft tissues of female crickets, but avoided their eggs by disposing of them on refuse piles. Bioassays using freshly collected cricket eggs showed that ants first retrieved eggs into their nests and then discarded them onto the refuse piles. The major chemicals on the surface of cricket eggs were found to be fatty acids, including lauric, myristic, palmitoleic, palmitic, linoleic, oleic, and stearic acid. Fatty acids are well-known death cues of insects and elicitors of widespread necrophoric behavior in ants. It was shown that both the cricket egg extract and the reconstructed fatty acid mixture elicited the necrophoric behavior of S. invicta; however, they never elicited retrieving behavior. Unknown chemicals on cricket eggs, other than fatty acids, might be responsible for the retrieving behavior. Interestingly, cricket eggs had a very similar fatty acid profile to that of dead ants collected from refuse piles. Possible causes for such a strong match in fatty acid profiles between dead ants and cricket eggs are discussed. [ABSTRACT FROM AUTHOR]

Background and Aims: The deposition of atmospheric nitrogen has increased globally and interfered with plant growth and development. However, only a few studies have examined the influence of atmospheric nitrogen deposition on plant–herbivore interactions in the framework of plant invasion, and the underlying mechanisms remain unclear. Methods: In this study, we examined the changes in growth and herbivore resistance of the invasive weed Alternanthera philoxeroides and its native co-occurring congener Alternanthera sessilis in response to simulated nitrogen deposition. We further investigated the competitive ability of these two plant species grown in mono- and mix-culture conditions with or without herbivore pressures. Results: The results indicated that simulated nitrogen deposition largely increased the growth of both plant species, while A. philoxeroides produced more biomass than A. sessilis. The specialist and generalist herbivores showed contrasting preferences for the two plant species in the controls, whereas A. philoxeroides showed greater resistance to both herbivore species under simulated nitrogen deposition. Further investigation of host plant traits related to leaf structural and chemical defences suggested that such difference in herbivore resistance between the two plant species could be attributed to the increased levels of structural defense in A. philoxeroides and reduced levels of defensive metabolites in A. sessilis. The inter-specific competition test revealed that simulated nitrogen deposition largely increased the competitive advantage of A. philoxeroides over A. sessilis, regardless of the presence or absence of herbivores. Conclusion: Our study suggests that the invasiveness of A. philoxeroides may be enhanced by increased atmospheric nitrogen deposition. [ABSTRACT FROM AUTHOR]

Raoiella indica Hirst has rapidly and widely spread throughout the New World since 2004, primarily infesting coconut palms and interacting with the predator Amblyseius largoensis (Muma). Although A. largoensis feeds on R. indica at all stages of development, it cannot naturally reduce its population to levels that do not impact the host plant. Raoiella indica possesses dorsal setae that secrete exudates during all post-embryonic developmental stages, and females have a behavior that deliberately deposits droplets on the freshly laid egg, possibly as a defense strategy against predation in vulnerable stages. In this context, we analyzed whether the presence or absence of droplets in R. indica eggs affects predation using A. largoensis as a biological model. Thus, we evaluated whether some biological and behavioral characteristics of A. largoensis could be affected by the consumption of R. indica egg masses washed or unwashed with water. Also, we performed a chemical analysis of the droplets exuded by R. indica and provided a description of the oviposition behavior of R. indica. The predator showed a higher consumption rate and preference for washed eggs. The results suggest that the exudate droplets have defensive functions, which are incorporated by the female onto the egg during oviposition and subsequently during a patrolling behavior, as they lose their effect after being washed with water. Although the droplets do not prevent the predator from feeding, they reduce the number of R. indica eggs consumed without affecting the growth of A. largoensis. [ABSTRACT FROM AUTHOR]

The purpose of this article is to give a comprehensive overview of the fascinating world of food webs, where plants play a key role. To highlight the importance of studying this area, understanding the issues involved, and applying the knowledge gained with respect for nature to agroecosystems including important permanent crops including orchards. Plants produce chemicals called secondary metabolites that play an indispensable role in their interactions with their environment. Plants use these substances to attract pollinators, defend themselves against herbivorous arthropods, attract predators or parasitoids of herbivores and communicate with each other. Recognizing these "SMALL" interactions can have BIG implications useful in the fields of ecology, medicine, and agriculture.

Dendrobatid poison frogs sequester alkaloids from an arthropod diet and use them in chemical defense. Alkaloid defenses vary considerably within and among species, with important consequences for the protection they can and do provide against microorganisms and predators. Most of this variation is attributed to differences in frog diet and prey availability, but emerging evidence also suggests that frogs differ in their physiological ability to sequester alkaloids. Epibatidines are one of the most geographically and phylogenetically restricted alkaloid classes in poison frogs, having been found naturally only in two genera of dendrobatids (Epipedobates and Ameerega) from Ecuador and northern Peru. To test the hypothesis that the ability to sequester epibatidine is confined to the lineages Epipedobates and Ameerega, we experimentally administered epibatidine to individuals of five species, representing three different lineages of dendrobatid poison frogs, including those known to possess (Epipedobates anthonyi) and lack (Ranitomeya variabilis, Ranitomeya imitator, Phyllobates vittatus, Dendrobates tinctorius) epibatidines in nature. All five species sequestered epibatidine; however, the percentage sequestered varied significantly across species with Epipedobates and Ranitomeya accumulating about 2.4× more than Phyllobates or Dendrobates. Our results suggest that the absence of epibatidine in certain dendrobatids is not due to the inability of these frogs to sequester epibatidine, but may instead result from differences in prey availability and/or dietary preference. Our finding of differences in the percentage of epibatidine sequestered among species points to the importance that physiological differences in sequestration play in explaining some of the alkaloid variation (including epibatidine) observed among dendrobatid poison frogs. [ABSTRACT FROM AUTHOR]

6-methoxybenzoxazolinone (6-MBOA) is a secondary plant metabolite predominantly found in monocotyledonous plants, especially Gramineae. In damaged tissue, 2-β-D-glucopyranosyloxy-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA-Glc) is hydrolyzed to DIMBOA, which spontaneously decomposes into 6-MBOA. It is commonly detected in plants consumed by voles and livestock and can also be present in cereal-based products. Discovered in 1955, this compound is renowned for its ability to trigger animal reproduction. However, there is a lack of research on its functional and mechanistic properties, leaving much of their potential unexplored. This review aimed to comprehensively summarize the effects of 6-MBOA on animal reproduction and human health, as well as its defensive role against herbivores. Studies have shown that 6-MBOA effectively inhibits the digestion, development, growth, and reproduction of insects. 6-MBOA may act as a partial agonist of melatonin and exert a regulatory role in mammalian reproduction, resulting in either promoting or inhibiting effects. 6-MBOA has been theorized to possess anti-tumor, anti-AIDS, anti-anxiety, and weight-loss effects in humans. However, insufficient attention has been paid to its defense properties against mammalian herbivores, and the mechanisms underlying its effects on mammalian reproduction remain unclear. In addition, research on its impact on human health is still in its preliminary stages. The review emphasizes the need for further systematic and comprehensive research on 6-MBOA to fully understand its diverse functions. Elucidating the effects of 6-MBOA on animal reproduction, adaptation, and human health would advance our understanding of plant–herbivore coevolution and the influence of environmental factors on animal population dynamics. Furthermore, this knowledge could potentially promote its application in human health and animal husbandry. [ABSTRACT FROM AUTHOR]

Plant induced responses to environmental stressors are increasingly studied in a behavioral ecology context. This is particularly true for plant induced responses to herbivory that mediate direct and indirect defenses, and tolerance. These seemingly adaptive alterations of plant defense phenotypes in the context of other environmental conditions have led to the discussion of such responses as intelligent behavior. Here we consider the concept of plant intelligence and some of its predictions for chemical information transfer in plant interaction with other organisms. Within this framework, the flow, perception, integration, and storage of environmental information are considered tunable dials that allow plants to respond adaptively to attacking herbivores while integrating past experiences and environmental cues that are predictive of future conditions. The predictive value of environmental information and the costs of acting on false information are important drivers of the evolution of plant responses to herbivory. We identify integrative priming of defense responses as a mechanism that allows plants to mitigate potential costs associated with acting on false information. The priming mechanisms provide short- and long-term memory that facilitates the integration of environmental cues without imposing significant costs. Finally, we discuss the ecological and evolutionary prediction of the plant intelligence hypothesis.

• Attack from natural enemies on plants may be reduced in metal contaminated sites. • Plants may elevate defenses to simultaneously deal with enemies and metal stress. • Herbivory was lower in a copper mine than adjacent site in four of seven plant species. • Mine site plants had more physical and chemical defenses than adjacent site plants. • Hyperaccumulator species showed relatively few increased defenses in the mine. Heavy metal pollution in soil can impact the relationships between plants and their natural enemies. Enemy attack from herbivores and pathogens is predicted to be lower in metal-contaminated areas such as mine sites. However, whether this is the case is remains to be tested. It is also unknown how defense traits differ in polluted sites compared to adjacent sites. To address this gap in knowledge, we compared the standing leaf damage in populations of two invasive and five native plant species at the abandoned Jiuhua copper mine and an adjacent site. We also compared physical and chemical defense traits of the populations. Herbivory on four plant species was significantly lower in a copper mine than in an adjacent site. Overall, plants growing in the mine were more physically and chemically defended than plants growing adjacent to the mine. Copper hyperaccumulator species (Cynodon dactylon and Kummerowia stipulacea) increased defense levels in the mine for only one of the traits. In contrast, defenses were higher in the mine site for most traits relative to their respective adjacent populations in the non-hyperaccumulator species. Our results suggest that the damage herbivores inflict on plants may be strongly influenced by how plants respond to stressors in mine site environments, such as metal pollution. Metal hyperaccumulation and increased non-elemental defenses may be alternate responses used by plants to simultaneously deal with metal pollution and natural enemies in contaminated sites. [ABSTRACT FROM AUTHOR]

Platyrrhines consume many species of arthropods in the order Orthoptera. Some species of orthopterans can produce chemical defenses that render them toxic or unpalatable and thus act as predator deterrents. These species include the stick grasshoppers (family Proscopiidae), which are widely distributed in the Caatinga biome in northeastern Brazil, which comprises part of the distribution of capuchin monkeys. Capuchin monkeys are omnivores and consume a wide variety of foods, including unpleasant-tasting, potentially toxic items, which they need to learn how to process. We describe the processing of stick grasshoppers (Stiphra sp.) by wild capuchin monkeys (Sapajus libidinosus) that live in Serra da Capivara National Park, Brazil, and compare how individuals of different age classes handle these potentially toxic food items. S. libidinosus predominantly avoided consuming the digestive tract, which contains toxic compounds, when feeding on stick grasshoppers. Immatures took longer than adults to process the stick grasshoppers, indicating that capuchins need to learn how to process the toxic digestive tract of these prey to avoid consuming it. [ABSTRACT FROM AUTHOR]

An approach based on the heat stress and microbial stress model of the medicinal plant Sparganium stoloniferum was proposed to elucidate the regulation and mechanism of bioactive phenol accumulation. This method integrates LC–MS/MS analysis, 16S rRNA sequencing, RT–qPCR, and molecular assays to investigate the regulation of phenolic metabolite biosynthesis in S. stoloniferum rhizome (SL) under stress. Previous research has shown that the metabolites and genes involved in phenol biosynthesis correlate to the upregulation of genes involved in plant–pathogen interactions. High-temperature and the presence of Pseudomonas bacteria were observed alongside SL growth. Under conditions of heat stress or Pseudomonas bacteria stress, both the metabolites and genes involved in phenol biosynthesis were upregulated. The regulation of phenol content and phenol biosynthesis gene expression suggests that phenol-based chemical defense of SL is stimulated under stress. Furthermore, the rapid accumulation of phenolic substances relied on the consumption of amino acids. Three defensive proteins, namely Ss4CL, SsC4H, and SsF3′5′H, were identified and verified to elucidate phenol biosynthesis in SL. Overall, this study enhances our understanding of the phenol-based chemical defense of SL, indicating that bioactive phenol substances result from SL's responses to the environment and providing new insights for growing the high-phenol-content medicinal herb SL. [ABSTRACT FROM AUTHOR]

Chemical defense in poison frogs derives from lipophilic alkaloids sequestered from dietary arthropods. Alkaloid composition varies extensively among individuals, populations, and species. Numerous causes of intraspecific variation have been identified, but the causes of interspecific variation are less clear, with both intrinsic (e.g., mechanism of sequestration) and extrinsic (e.g., arthropod availability) explanations being possible. Sympatric species afford a unique opportunity to investigate the causes and consequences of interspecific variation in natural populations, since they are potentially exposed to the same arthropod prey and predators. We used gas chromatography–mass spectrometry to identify alkaloids from 36 individuals of six species and three genera of dendrobatid poison frogs (Adelphobates, Ameerega, and Ranitomeya) collected in three Amazonian localities. We then compared alkaloid composition, richness, and quantity among sympatric species and analyzed the variation in alkaloid composition among con- and heterospecific populations at the two nearest localities. We also performed arthropod palatability experiments to investigate the biological significance of differences in alkaloids among sympatric species. Sympatric species differed in alkaloid composition, richness, and quantity, and conspecific individuals from different localities shared more alkaloids than heterospecific individuals from the same locality, strongly suggesting that variation is due to intrinsic causes. All analyzed alkaloid secretions were unpalatable, but palatability scores did not differ for most sympatric species, despite significant differences in alkaloid composition, richness, and quantity. Our results provide insights into the causes and consequences of interspecific variation in alkaloid profiles, but additional data are required to identify specific intrinsic causes and predator responses. [ABSTRACT FROM AUTHOR]

Large, conspicuous traits frequently evolve despite increased predator attention, but in some cases, specifically to attract attention. Sexually selected traits provide some of the clearest examples of elaboration, yet natural selection can also be a powerful driver. The matador bug, Anisoscelis alipes (Hemiptera: Coreidae), has large, colorful flags on its hindlegs that, unlike many other coreid species, are not used in reproductive competition. We hypothesized that these flags either 1) warn predators of chemical defense or 2) deflect predatory attack to the removable hindlegs. We pitted matador bugs with or without flags and crickets (Acheta domesticus) with or without bug flags experimentally attached to their legs, against live motmot bird predators (Momotus subrufescens and Electron platyrhynchum). Contrary to the deflection hypothesis, almost none of the predatory strikes were directed at hindleg flags. Instead, we found support for the aposematism hypothesis: matador bug flags reduced attacks on palatable crickets but were unnecessary to prevent predator attacks against matador bugs. Palatability studies with naïve chicks (Gallus gallus) further supported a chemical defense hypothesis. Thus, these elaborate hindleg flags serve an aposematic anti-predator function, but in their absence, birds use alternative cues. These findings add to our understanding of the role of predation in driving the evolution of elaborate morphological structures. [ABSTRACT FROM AUTHOR]

Sea cucumbers frequently expel their guts in response to predators and an aversive environment, a behavior perceived as releasing repellents involved in chemical defense mechanisms. To investigate the chemical nature of the repellent, the viscera of stressed sea cucumbers (Apostichopus japonicus) in the Yellow Sea of China were collected and chemically analyzed. Two novel non-holostane triterpene glycosides were isolated, and the chemical structures were elucidated as 3ꞵ-O-[ꞵ-D-glucopyranosyl-(1→2)-ꞵ-D-xylopyranosyl]-(20S)-hydroxylanosta-7,25-diene-18(16)-lactone (1) and 3ꞵ-O-[ꞵ-D-quinovopyranosyl-(1→2)-ꞵ-D-xylopyranosyl]-(20S)-hydroxylanosta-7,25-diene-18(16)-lactone (2) by spectroscopic and mass-spectrometric analyses, exemplifying a triterpene glycoside constituent of an oligosaccharide containing two sugar-units and a non-holostane aglycone. Zebrafish embryos were exposed to various doses of 1 and 2 from 4 to 96 hpf. Compound 1 exposure showed 96 h-LC50 41.5 µM and an increased zebrafish mortality rates in roughly in a dose- and time-dependent manner. Compound 2, with different sugar substitution, exhibited no mortality and moderate teratogenic toxicity with a 96 h-EC50 of 173.5 µM. Zebrafish embryos exhibited teratogenic effects, such as reduced hatchability and total body length. The study found that triterpene saponin from A. japonicus viscera had acute toxicity in zebrafish embryos, indicating a potential chemical defense role in the marine ecosystem. [ABSTRACT FROM AUTHOR]

The Nicotiana genus, commonly known as tobacco, holds significant importance as a crucial economic crop. Confronted with an abundance of herbivorous insects that pose a substantial threat to yield, tobacco has developed a diverse and sophisticated array of mechanisms, establishing itself as a model of plant ecological defense. This review provides a concise overview of the current understanding of tobacco’s defense strategies against herbivores. Direct defenses, exemplified by its well-known tactic of secreting the alkaloid nicotine, serve as a potent toxin against a broad spectrum of herbivorous pests. Moreover, in response to herbivore attacks, tobacco enhances the discharge of volatile compounds, harnessing an indirect strategy that attracts the predators of the herbivores. The delicate balance between defense and growth leads to the initiation of most defense strategies only after a herbivore attack. Among plant hormones, notably jasmonic acid (JA), play central roles in coordinating these defense processes. JA signaling interacts with other plant hormone signaling pathways to facilitate the extensive transcriptional and metabolic adjustments in plants following herbivore assault. By shedding light on these ecological defense strategies, this review emphasizes not only tobacco’s remarkable adaptability in its natural habitat but also offers insights beneficial for enhancing the resilience of current crops. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Gfeller et al. (2024), 241: 2575–2588. [ABSTRACT FROM AUTHOR]

Alien plants' chemical defenses against herbivores contribute to how successful they are at invading, but the defensive chemicals and their biosynthesis are sometimes poorly characterized, which limits pest management and control of invasive species. Here, the chemical defenses of invasive plant Phytolacca americana and noninvasive Phytolacca icosandra in China against generalist herbivore Spodoptera litura were compared. When plants were free from herbivores' attack, P. americana repelled S. litura females to P. icosandra. After being infested with S. litura, P. americana formed an ecological trap, which attracted S. litura to lay eggs but caused the emerged larvae to grow poorly. Further analysis found that constitutively released (Z)-3-hexenyl acetate (z3HAC) attracted S. litura females, while the herbivore-induced volatile DMNT with z3HAC repelled them. P. americana had alcohol acyltransferase genes (AATs) for z3HAC biosynthesis, but low gene expression levels of target AATs, low enzyme catalytic ability of AATs, and low level of the endogenous precursor of (Z)-3-hexen-1-ol led to undetectable levels of z3HAC. Highly enriched metabolites of organic acids and flavonoids from phenylalanine metabolism in P. americana deterred the growth of S. litura. These results suggested that invasive P. americana avoided synthesizing costly z3HAC and accumulated organic acids and flavonoids to defend against generalists, unlike its noninvasive congener, providing new insights into invasion success and pest management. [ABSTRACT FROM AUTHOR]

Toads of the genus Atelopus are chemically defended by a unique combination of endogenously synthesized cardiotoxins (bufadienolides) and neurotoxins which may be sequestered (guanidinium alkaloids). Investigation into Atelopus small-molecule chemical defenses has been primarily concerned with identifying and characterizing various forms of these toxins while largely overlooking their ecological roles and evolutionary implications. In addition to describing the extent of knowledge about Atelopus toxin structures, pharmacology, and biological sources, we review the detection, identification, and quantification methods used in studies of Atelopus toxins to date and conclude that many known toxin profiles are unlikely to be comprehensive because of methodological and sampling limitations. Patterns in existing data suggest that both environmental (toxin availability) and genetic (capacity to synthesize or sequester toxins) factors influence toxin profiles. From an ecological and evolutionary perspective, we summarize the possible selective pressures acting on Atelopus toxicity and toxin profiles, including predation, intraspecies communication, disease, and reproductive status. Ultimately, we intend to provide a basis for future ecological, evolutionary, and biochemical research on Atelopus.

The obligate marine actinobacterial genus Salinispora has become a model organism for natural product discovery, yet little is known about the ecological functions of the compounds produced by this taxon. The aims of this study were to assess the effects of live cultures and culture extracts from two Salinispora species on invertebrate predators. In choice-based feeding experiments using the bacterivorous nematode Caenorhabditis elegans, live cultures of both Salinispora species were less preferred than Escherichia coli. When given a choice between the two species, C. elegans preferred S. areniolca over S. tropica. Culture extracts from S. tropica deterred C. elegans, while those from S. arenicola did not, suggesting that compounds produced by S. tropica account for the feeding deterrence. Bioactivity-guided isolation linked compounds in the lomaiviticin series to the deterrent activity. Additional assays using the marine polychaete Ophryotrocha siberti and marine nematodes further support the deterrent activity of S. tropica against potential predators. These results provide evidence that Salinispora natural products function as a defense against predation and that the strategies of predation defense differ between closely related species. IMPORTANCE Bacteria inhabiting marine sediments are subject to predation by bacterivorous eukaryotes. Here, we test the hypothesis that sediment-derived bacteria in the genus Salinispora produce biologically active natural products that function as a defense against predation. The results reveal that cultures and culture extracts of S. tropica deter feeding by Caenorhabditis elegans and negatively affect the habitat preference of a marine annelid (Ophryotrocha siberti). These activities were linked to the lomaiviticins, a series of cytotoxic compounds produced by S. tropica. Microbial natural products that function as a defense against predation represent a poorly understood trait that can influence community structure in marine sediments.

Coating seeds in taste-averting chemical defenses (e.g., capsaicin from Capsicum spp.) can reduce rodent seed predation, and thus might promote plant establishment and forest regeneration. However, the efficacy of such seed coatings remains unknown for many woody plant species, and seed coatings have not been evaluated across different habitats where forest managers might seek to promote forest regeneration. We used two complementary seed-removal experiments in closed-canopy forests (Michigan) and an old field undergoing reforestation (New York) to examine whether coating seeds of four native tree species (Acer rubrum, Fagus grandifolia, Pinus banksiana, and Pinus resinosa) with chili powder reduces seed removal by rodents. In all species and habitats, control seeds were removed more than seeds treated with capsaicin (94% more in the closed-canopy forest, 17% more in the old field). Seed coatings containing capsaicin may provide a generally effective tool to support native tree recruitment and promote restoration success. [ABSTRACT FROM AUTHOR]

Objective / Background. The objective was to assess the biocontrol capacity of Bacillus sp. A8a in avocado (Persea americana) plants infected by Phytophthora cinnamomi. Materials and Methods. A greenhouse experiment was implemented with four treatments: 1) control plants; 2) plants infected with P. cinnamomi; 3) plants inoculated with Bacillus sp. A8a; 4) plants infected with P. cinnamomi and inoculated with Bacillus sp. A8a. We evaluated several morpho-physiological variables during the experiment, which lasted 25 days after infection (dai). Moreover, we analyzed tannin density in stems at 25 dai to determine the plant defense response against the disease. Results. Inoculation with strain A8a reduced wilting symptoms by 49 % at 25 dai, compared with non-inoculated plants. No differences were detected in morphophysiological variables between treatments. However, a greater tannin accumulation was registered in the xylem of infected plants, whilst plants inoculated with strain A8a displayed a larger tannin density in the cortex. Conclusion. Our results confirm the biocontrol activity of Bacillus sp. A8a in avocado plants and suggest that tannin differential accumulation in the cortex of plants inoculated with the bacteria may contribute to the enhanced tolerance of avocado plants against Phytophthora root rot. [ABSTRACT FROM AUTHOR]

Euphorbia dentata (Euphorbiaceae), an invasive weed, is rarely eaten by herbivorous insects and could secrete a large amount of white latex, causing a serious threat to local natural vegetation, agricultural production and human health. In order to prevent this plant from causing more negative effects on humans, it is necessary to understand and utilize the chemical relationships between the latex of E. dentata and herbivorous insects. In this study, three new norsesquiterpenes (1–3), together with seven known analogues (4–10), were isolated and identified from the latex of E. dentata. All norsesquiterpenes (1–10) showed antifeedant and growth-inhibitory effects on H. armigera with varying levels, especially compounds 1 and 2. In addition, the action mechanisms of active compounds (1–3) were revealed by detoxifying enzyme (AchE, CarE, GST and MFO) activities and corresponding molecular docking analyses. Our findings provide a new idea for the development and utilization of the latex of E. dentata, as well as a potential application of norsesquiterpenes in botanical insecticides. [ABSTRACT FROM AUTHOR]

Biological toxins are entrenched within ecosystems. Thus, animals are often exposed to such toxins, and how they adapt can be a key determinant of their evolutionary trajectories. In this review, we provide an overview of the diversity of toxin resistance mechanisms, with a focus on animals that sequester toxins from their diet and their natural predators and parasites. We propose a structured framework in which to study toxin resistance by recategorizing and reorganizing known mechanisms into avoidance, metabolism, and target categories. Then, using this framework, we review evidence regarding how animals resist four widely studied compounds: tetrodotoxin, batrachotoxin, cardiotonic steroids, and pyrrolizidine alkaloids. Based on the available data, we conclude that toxin resistance and sequestration are interrelated from both ecological and evolutionary perspectives. To conclude, we highlight open questions regarding toxin resistance and review its importance as a field. En los ecosistemas las toxinas de origen biológico son componentes intrínsecos. Por esta razón, los animales se ven expuestos frecuenciamente a dichas toxinas y la forma en que se adaptan puede ser un factor que determina su trayectoria evolutiva. Esta revisión ofrece una visión general de la diversidad de mecanismos de resistencia a toxinas, centrándose en animales que secuestran toxinas de su dieta y en sus depredadores y parásitos naturales. En este texto se propone un marco estructural para estudiar la resistencia a toxinas mediante la recategorización y reorganización de mecanismos conocidos en categorías de: evación, metabolismo y moléculas diana. A continuación, utilizando este marco, revisamos la literatura científica en busca de evidencia sobre cómo los animales resisten a cuatro compuestos ampliamente estudiados: tetrodotoxina, batracotoxina, esteroides cardiotónicos y alcaloides de pirrolizidina. A partir de los datos disponibles, llegamos a la conclusión de que la resistencia y la retención de toxinas están interrelacionadas tanto desde el punto de vista ecológico como evolutivo. Por último, destacamos algunas preguntas abiertas en torno a la resistencia a las toxinas y resaltamos su importancia como campo de estudio en el futuro. [ABSTRACT FROM AUTHOR]

Chemical elicitors can increase plant defense against herbivorous insects and pathogens. The use of synthetic chemical elicitors is likely to be an alternative to traditional pesticides for crop pest control. However, only a few synthetic chemicals are reported to protect plants by regulating signaling pathways, increasing the levels of defense metabolites and interfering with insect feeding. Here, we found that the exogenous application of a phenoxycarboxylic compound, 4-chlorophenoxyacetic acid (4-CPA), can induce chemical defenses to protect rice plants from white-backed planthoppers (WBPH, Sogatella furcifera). Four-CPA was rapidly taken up by plant roots and degraded to 4-chlorophenol (4-CP). Four-CPA treatment modulated the activity of peroxidase (POD) and directly induced the deposition of lignin-like polymers using hydrogen peroxide (H2O2) as the electron acceptor. The polymers, which are thought to prevent the planthopper's stylet from reaching the phloem, were broken down by WBPH nymphs. Meanwhile, 4-CPA increased the levels of flavonoids and phenolamines (PAs). The increased flavonoids and PAs, together with the degradation product of the polymers, avoided nymphal feeding and prolonged the nymphal period for 1 day. These results indicate that 4-CPA has the potential to be used as a chemical elicitor to protect rice from planthoppers. Moreover, these findings also open a pathway for molecule structure design of phenoxycarboxylic compounds as chemical elicitors. [ABSTRACT FROM AUTHOR]

Evolutionary correlations between chemical defense and protection by mutualist bodyguards have been long predicted, but tests of these patterns remain rare. We use a phylogenetic framework to test for evolutionary correlations indicative of trade-offs or synergisms between direct defense in the form of plant secondary metabolism and indirect defense in the form of leaf domatia, across 33 species in the wild grape genus, Vitis. We also performed a bioassay with a generalist herbivore to associate our chemical phenotypes with herbivore palatability. Finally, we tested whether defensive traits correlated with the average abiotic characteristics of each species' contemporary range and whether these correlations were consistent with plant defense theory. We found a negative evolutionary correlation between domatia size and the diversity of secondary metabolites in Vitis leaf tissue across the genus, and also that leaves with a higher diversity and richness of secondary metabolites were less palatable to a generalist herbivore, consistent with a trade-off in chemical and mutualistic defense investment. Predictions from plant defense theory were not supported by associations between investment in defense phenotypes and abiotic variables. Our work demonstrates an evolutionary pattern indicative of a trade-off between indirect and direct defense strategies across the Vitis genus. [ABSTRACT FROM AUTHOR]

Insects avoid predation in various ways, and some use multiple ways to avoid predation. However, the effects of comprehensive avoidance methods and the differences in avoidance methods among different life stages of insects have not been sufficiently discussed. The big head stick insect Megacrania tsudai uses background matching as its primary defense and chemical defense as its secondary defense. The aims of this study were to identify and isolate the chemical components of M. tsudai using repeatable methods, determine the amount of the main chemical compound, and reveal the effect of the main chemical compound on its predators. We established a repeatable gas chromatography-mass spectrometry (GC–MS) method to identify the chemical compounds of these secretions, and identified actinidine as the main compound. Actinidine was identified by nuclear magnetic resonance (NMR), and the amount of actinidine in each instar was calculated by constructing a calibration curve using pure actinidine. Mass ratios did not drastically change among instars. Furthermore, experiments involving dropping an aqueous solution of actinidine demonstrated removal behavior in geckos, frogs, and spiders. These results indicated that M. tsudai conducts secondary defenses using defensive secretions consisting mainly of actinidine. [ABSTRACT FROM AUTHOR]

Laurencia seaweed species synthesize a broad range of secondary metabolites, mainly terpenes (e.g., elatol), exhibiting diverse ecological roles, such as defense against fouling and herbivores. Recently, an intricate cellular machinery was described concerning terpenes biosynthetic pathways, storage inside corps en cerise (CC), and regulated exocytosis in these species. But for seaweeds in general, the proteins involved in transmembrane transport of secondary metabolites remain unknown. Assays with Rhodamine-123 and cyclosporine A (CSA) revealed the presence of ABC transporters in CC membrane of Laurencia dendroidea. In vivo incubation assays with CSA resulted in CC morphological changes, reduced intracellular elatol concentrations, and increased biofouling cover on the seaweed surface. Cultivation assays in the presence of a marine pathogenic bacteria induced the expression of ABC proteins belonging to the subfamilies ABCB, ABCD, ABCF, and ABCG. The latter subfamily is known to be associated with the transport of plant terpenes. Our results shed new light on the role of ABC proteins in key mechanisms of the defensive system in seaweeds against fouling and herbivory. [ABSTRACT FROM AUTHOR]

Abstract Sponges perform important ecosystem functions, host diverse microbial symbiont communities (microbiomes), and have been increasing in density on Caribbean coral reefs over the last decade. Sponges compete for space in coral reef communities through both morphological and allelopathic strategies, but no studies of microbiome impacts during these interactions have been conducted. Microbiome alterations mediate spatial competition in other coral reef invertebrates and may similarly impact competitive outcomes for sponges. In this study, we characterized the microbiomes of three common Caribbean sponges (Agelas tubulata, Iotrochota birotulata, and Xestospongia muta) observed to naturally interact spatially in Key Largo, Florida (USA). For each species, replicate samples were collected from sponges in contact with neighbors at the site of contact (contact) and distant from the site of contact (no contact), and from sponges spatially isolated from neighbors (control). Next‐generation amplicon sequencing (V4 region of 16S rRNA) revealed significant differences in microbial community structure and diversity among sponge species, but no significant effects were observed within sponge species across all contact states and competitor pairings, indicating no large community shifts in response to direct contact. At a finer scale, particular symbiont taxa (operational taxonomic units at 97% sequence identity, OTUs) were shown to decrease significantly in some interaction pairings, suggesting localized effects for specific sponge competitors. Overall, these results revealed that direct contact during spatial competition does not significantly alter microbial community composition or structure of interacting sponges, suggesting that allelopathic interactions and competitive outcomes are not mediated by microbiome damage or destabilization.

The chemical defense of insects is effective for avoiding predation, but may carry a cost in terms of life history traits. If chemical defenses require the resources and/or nutrients necessary for the larva or post-larval stages to survive, grow, and reproduce, there will be a trade-off between chemical defense and other traits, particularly in habitats where larvae are subjected to frequent predator attacks. The larvae of Osmylus hyalinatus McLachlan (Neuroptera: Osmylidae) are semiaquatic, inhabiting the edges of small streams and ponds, where they encounter multiple predators both on land and in water. Larvae of this species spray a hyaline liquid from an anal opening when disturbed. The liquid is stored in the posterior half of the hindgut. Daily stimulation of larvae to exhaust the stored liquid, thereby simulating repeated predator attacks, resulted in smaller adult body size at emergence than the control, but had little effect on the larval/pupal period, cocoon production (for predator avoidance of prepupae and pupae), reproductive potential, or chemical defense of adults in which prothoracic glands release a substance that smells unpleasant to predators. The lack of such effects is explained in part by adults gaining more resources through feeding than the larval stages, as well as nuptial gifts from males to females. The spraying liquids and silk used to spin cocoons are both discharged from an anal opening; therefore, a trade-off between these two materials is plausible and should be examined in the future. [ABSTRACT FROM AUTHOR]

The Argentine ant is one of the five worst invasive ants. Recently it has been shown that one of the main compounds of its pygidial gland, iridomyrmecin, is used as a venom against competitors and enemies. Here, we explore the variability in the quantities of iridomyrmecin of individual workers, along a range of locations pertaining to both its native and invasive ranges, in order to know whether its venom could have contributed to the differential invasion success of European supercolonies. We specifically compared the amount of iridomyrmecin among supercolonies in the native range and among three invasive supercolonies: the Main supercolony (the most extended worldwide), the Corsican and the Catalonian supercolonies (both with a restricted distribution in Europe). Our main result is that the variability of the iridomyrmecin is very high. Looking at mean values, we found that the amount of iridomyrmecin of the Main supercolony was the lowest while the highest corresponded to the Corsican supercolony, with the Catalonian and the native range supercolonies having intermediate values. However, variability in the values within each supercolony was similar between supercolonies. This suggests that the success of a given invasive supercolony may not be explained by higher quantities of this defensive compound. Our results open the way for exploring the connection between defensive compounds and the invasion success of this global invader. [ABSTRACT FROM AUTHOR]

Many herbivorous Lepidoptera accumulate plant toxins within their own tissues as a defensive strategy. Pioneering research in this area was conducted by Miriam Rothschild and Deane Bowers, who showed that the cycad-feeding butterfly Eumaeus atala sequester the toxic plant compound cycasin and thereby deter vertebrate and invertebrate predators. The current study focuses on another cycad compound, β-methylamino-L-alanine (BMAA), that is known to accumulate in the tissues of insects and other herbivores, and which has been shown to have neurotoxic effects in humans. Chemical analyses revealed that BMAA accumulates in both immature and adult tissues of E. atala, as well as adult tissues of another cycad-feeding lepidopteran, Seirarctia echo. However, the distribution of BMAA across life stages and tissues did not conform to patterns predicted for defensive sequestration, and subsequent behavioral experiments with ants showed that these invertebrate predators were not deterred by BMAA. Our results suggest that high levels of BMAA in the tissues of cycad-feeding insects likely reflect passive bioaccumulation rather than defensive sequestration. Combined with the previous work by Rothschild and Bowers, these results provide an example in which two different plant toxins accumulate within the tissues of a single herbivore species via different mechanisms and with different implications for ecology and evolution. They thereby lay the groundwork for further investigation into the processes underlying active sequestration and non-adaptive bioaccumulation.

Summary: The economic and ecologically important genus Eucalyptus is rich in structurally diverse specialized metabolites. While some specialized metabolite classes are highly prevalent across the genus, the cyanogenic glucoside prunasin is only produced by c. 3% of species.To investigate the evolutionary mechanisms behind prunasin biosynthesis in Eucalyptus, we compared de novo assembled transcriptomes, together with online resources between cyanogenic and acyanogenic species. Identified genes were characterized in vivo and in vitro.Pathway characterization of cyanogenic Eucalyptus camphora and Eucalyptus yarraensis showed for the first time that the final glucosylation step from mandelonitrile to prunasin is catalyzed by a novel UDP‐glucosyltransferase UGT87. This step is typically catalyzed by a member of the UGT85 family, including in Eucalyptus cladocalyx. The upstream conversion of phenylalanine to mandelonitrile is catalyzed by three cytochrome P450 (CYP) enzymes from the CYP79, CYP706, and CYP71 families, as previously shown. Analysis of acyanogenic Eucalyptus species revealed the loss of different ortholog prunasin biosynthetic genes.The recruitment of UGTs from different families for prunasin biosynthesis in Eucalyptus demonstrates important pathway heterogeneities and unprecedented dynamic pathway evolution of chemical defense within a single genus. Overall, this study provides relevant insights into the tremendous adaptability of these long‐lived trees. [ABSTRACT FROM AUTHOR]

Research on the invasive plant Phytolacca americana (L.) mostly focuses on its medicinal value and enrichment of heavy metals. However, little is known regarding its impact on native herbivorous insects. In this study, we explored the effects of P. americana and the exotic noninvasive Phytolacca icosandra (L.) on the Spodoptera litura (Fabricius) (native tobacco cutworm) via bioassay, oviposition preference, detoxifying enzyme activity analysis, and phytochemical determination. We found that the oviposition preference index (OPI) of S. litura feeding on P. icosandra was higher than that of P. americana. The developmental duration of S. litura feeding on P. icosandra was shorter than that of P. americana. Additionally, the Acetylcholinesterase (AchE) and Glutathione-S-transferase (GST) activities of S. litura feeding on P. americana were higher than that of S. litura feeding on artificial diets or P. icosandra. The content of lignin and flavonoids in P. americana was relatively high, whereas starch content was relatively low. These findings suggest invasive plants have higher resistance to herbivores, thereby suffering less damage than exotic noninvasive plants. [ABSTRACT FROM AUTHOR]

Summary: Plants are widely recognized as chemical factories, with each species producing dozens to hundreds of unique secondary metabolites. These compounds shape the interactions between plants and their natural enemies. We explore the evolutionary patterns and processes by which plants generate chemical diversity, from evolving novel compounds to unique chemical profiles.We characterized the chemical profile of one‐third of the species of tropical rainforest trees in the genus Inga (c. 100, Fabaceae) using ultraperformance liquid chromatography‐mass spectrometry‐based metabolomics and applied phylogenetic comparative methods to understand the mode of chemical evolution.We show: each Inga species contain structurally unrelated compounds and high levels of phytochemical diversity; closely related species have divergent chemical profiles, with individual compounds, compound classes, and chemical profiles showing little‐to‐no phylogenetic signal; at the evolutionary time scale, a species' chemical profile shows a signature of divergent adaptation. At the ecological time scale, sympatric species were the most divergent, implying it is also advantageous to maintain a unique chemical profile from community members; finally, we integrate these patterns with a model for how chemical diversity evolves.Taken together, these results show that phytochemical diversity and divergence are fundamental to the ecology and evolution of plants. [ABSTRACT FROM AUTHOR]

Bacterial populations face the constant threat of viral predation exerted by bacteriophages ('phages'). In response, bacteria have evolved a wide range of defense mechanisms against phage challenges. Yet the vast majority of antiphage defense systems described until now are mediated by proteins or RNA complexes acting at the single-cell level. Here, we review small molecule-based defense strategies against phage infection, with a focus on the antiphage molecules described recently. Importantly, inhibition of phage infection by excreted small molecules has the potential to protect entire bacterial communities, highlighting the ecological significance of these antiphage strategies. Considering the immense repertoire of bacterial metabolites, we envision that the list of antiphage small molecules will be further expanded in the future. Bacteria are prolific metabolite producers, but the role of this metabolite diversity in protection against phages has been only recently appreciated. Anthracyclines, aminoglycosides, and chain terminators produced by prokaryotic viperins represent the main classes of antiphage small molecules known to date. Aminoglycosides have both antibacterial and antiphage properties, this dual function making them an interesting example of molecular multitasking. Secreted antiphage metabolites have the potential to protect bacterial communities, serving as a multicellular defense strategy. [ABSTRACT FROM AUTHOR]

Premise: Why have pollen grains evolved to be exceptionally large in some species? Pollen‐feeding hypothesis suggests that if the proportion of pollen amounts for feeding is reduced in a flower, the low allocation to pollen number would allow pollen grains to be larger. Methods: To examine whether species with large pollen grains experience low pollen consumption, the behavior of insects feeding on nectar and pollen was observed and pollen transfer efficiency was estimated for four visitor types in Geranium delavayi. To see whether bees actively collected pollen, the numbers of grains in pollen baskets and on the body were compared. Both nutritional value (total protein and lipid) and chemical defense (phenolic metabolites) in pollen against pollen feeders were measured. Results: Bumblebees and honeybees foraged for nectar, rarely groomed pollen into corbiculae, and had >5× higher pollen transfer efficiency than smaller solitary bees and flies, which were pollen eaters that removed more pollen but deposited less. Pollen grains were characterized by low protein and high lipid content with a low protein‐lipid ratio, an unfavorable combination for bumblebees. Three secondary metabolites were significantly higher in pollen grains (7.77 mg/g) than in petals (1.08 mg/g) or in nectar (0.44 mg/g), suggesting stronger chemical defense in pollen. Conclusions: Our results indicated that large bees took nectar but little of the nutritionally poor and highly toxic pollen. These data support one prediction of the pollen‐feeding hypothesis, that species with few and large pollen grains would also have low pollen‐consumption rates. [ABSTRACT FROM AUTHOR]

Changes in leaf traits in response to plant–plant interactions affect feeding by insect herbivores. However, the effects of such changes on feeding by vertebrate herbivores remain unclear. We examined the effects of interactions of Aster leiophyllus collected in the field (growing with plants of the same species [aggregated] or with plants of different species [solitary]) or grown in pots (with another A. leiophyllus [intraspecific] or with Carex aphanolepis or Thalictrum baicalense [interspecific]) on the concentration of total phenolics in A. leiophyllus leaves and on sika deer (Cervus nippon) grazing preference in Japan. Deer were presented for 30 s with the first A. leiophyllus leaf (from either aggregated plants or solitary plants) and then for 30 s with the second leaf (solitary or aggregated, respectively). All of the deer presented first with a leaf from a solitary plant ate it, but when deer were presented first with a leaf from an aggregated plant, which had a higher concentration of total phenolics, 50% rejected or left it. About a third of the deer that had been presented first with a leaf from an aggregated plant subsequently rejected the leaf of a solitary plant. The leaves in the intraspecific interaction pot treatment had higher total phenolic concentration and were rejected more by deer than the leaves in the interspecific treatments. Plant–plant interactions affected deer preference, which was also influenced by learning. These results should improve our understanding of both plant grazing by deer and environmental management. [ABSTRACT FROM AUTHOR]

A vast diversity of parasites associates with ants. Living in and around ant nests of these organisms must overcome ant colony defenses. As ant defensive behavior is mainly mediated by species-specific cuticular hydrocarbons (CHCs) or alarm pheromones, and ant-associated parasites can either crack their hosts' chemical communication code by modifying their own CHC profiles or use pro-active strategies like chemical weaponry for distraction and repellency. While the chemical nature of ant–parasite interactions has been intensively studied for highly host-specific parasites, the chemical-deceptive strategies of the rather rare ant-resembling heteropterans are unknown. To gain insight into this system, I studied the bug Scolopostethus pacificus (Barber 1918) which can be found near the nests of the ecologically dominant and aggressive velvety tree ant (Liometopum occidentale, Emery 1895). Using behavioral, chemical, and molecular approaches, I disentangled the relationship of S. pacificus and its host ant. Chemical profiling of the bug and the ant revealed that the bug does not make use of CHC insignificance or mimicry, but instead uses a cocktail of volatile compounds released from its metathoracic glands that likely moderates encounters with its aggressive host. Feeding trials with armed and artificially disarmed bugs revealed a defensive function of the gland exudates. Targeted molecular gut barcoding showed that S. pacificus does not feed on L. occidentale. These results suggest that chemical weaponry, rather than a chemical code-cracking CHC matching or chemical insignificance, enables S. pacificus to get along with and live in close proximity to its host ant. [ABSTRACT FROM AUTHOR]

The scent gland secretion of an undetermined species of Prionostemma from Costa Rica was analyzed by gas chromatography–mass spectrometry and shown to consist of medium-chain carboxylic acids (mainly octanoic acid) and a ß-hydroxy-carboxylic acid, eventually identified as myrmicacin (= (R)-3-hydroxydecanoic acid). While scent gland secretions in harvestmen have traditionally been considered to be products of de novo synthesis, we here provide evidence for the unusual case of sequestration-derived scent gland constituents: at least myrmicacin appears to be sequestered from leaf-cutter ants that constitute a part of the prey of the Prionostemma-species herein investigated. This is the first report on the scent gland chemistry of the sclerosomatid subfamily Gagrellinae as well as on a possible sequestration mechanism in harvestmen. [ABSTRACT FROM AUTHOR]

Abstract Plants constantly cope with insect herbivory, which is thought to be the evolutionary driver for the immense diversity of plant chemical defenses. Herbivorous insects are in turn restricted in host choice by the presence of plant chemical defense barriers. In this study, we analyzed whether butterfly host–plant patterns are determined by the presence of shared plant chemical defenses rather than by shared plant evolutionary history. Using correlation and phylogenetic statistics, we assessed the impact of host–plant chemical defense traits on shaping northwestern European butterfly assemblages at a macroevolutionary scale. Shared chemical defenses between plant families showed stronger correlation with overlap in butterfly assemblages than phylogenetic relatedness, providing evidence that chemical defenses may determine the assemblage of butterflies per plant family rather than shared evolutionary history. Although global congruence between butterflies and host–plant families was detected across the studied herbivory interactions, cophylogenetic statistics showed varying levels of congruence between butterflies and host chemical defense traits. We attribute this to the existence of multiple antiherbivore traits across plant families and the diversity of insect herbivory associations per plant family. Our results highlight the importance of plant chemical defenses in community ecology through their influence on insect assemblages.

The risk of predation and the costs and benefits of diverse anti-predator strategies can shift across the life stages of an organism. Yet, empirical examples of ontogenetic switches in defense mechanisms are scarce. Anurans represent an alleged exception; previous meta-analytic work suggests that unpalatability of developing anurans is "rare", whereas adult anurans in many lineages are well defended by toxic and/or unpalatable skin secretions. Here, we revisit the question of the unpalatability of anuran young in a meta-analysis of the relative proportion of prey consumed within 922 predation tests, including 135 anuran species. We tested the hypotheses that a predator's propensity to consume anuran young depends on (1) prey family, (2) predator manipulation strategy, and (3) prey ontogenetic stage. We used a binomial mixed model approach with considerations for multiple effect sizes within studies to evaluate the log odds ratio of the proportion of prey consumed by individual predators. Prey consumption was highly variable, but toads (Bufonidae) were consumed in lower proportions. Chewing invertebrates consumed more anuran prey than biting vertebrates. Late stage tadpoles were more vulnerable to predation than other stages of anuran ontogeny. However, more studies are needed to unravel the roles of development and evolutionary history in the chemical ecology of anuran young. This synthesis provides clear meta-analytic evidence that relative unpalatability is an important component in the anti-predator defenses of young in some anuran families, calling into question the degree to which chemically defended anuran families undergo ontogenetic switches in anti-predator strategies. [ABSTRACT FROM AUTHOR]

[Objective] This study investigated sexual differences in growth and defense of Salix viminalis seedlings in different growing stages to provide guidance for gender difference research and selective application of male and female plants in practice. [Method] Male and female one-year-old cutting seedlings of S. viminalis were selected, and the growth, photosynthetic parameters, photosynthetic pigment contents, chemical defense substance content and defense enzyme activities were measured and analyzed with the design of completely randomized blocks under field experiment conditions on June 5, July 3, August 4, September 7 and October 5. [Result] There were no significant gender differences in plant height in June and ground diameter in June and July, but the height and ground diameter of male plants were significantly higher than those of female plants at other dates. The net photosynthetic rate (Pn) and transpiration rate (Tr) showed no significant gender difference in June, while the Pn and Tr of male plants were significantly higher than those of female plants from July to October. The stomatal conductance (Gs) showed no significant gender difference from June to September, while the Gs of male plants was significantly higher than that of female plants in October. The intercellular CO2 concentration (Ci) showed no significant gender difference from June to October. The contents of chlorophyll a (Chi a), chlorophyll b (Chi b) and carote-noid (Car) showed no significant gender difference in June, while the photosynthetic pigment contents of male plants were significantly higher than those of female plants from July to October. There was no significant difference in contents of secondary metabolites (polyphenols and tannins) between males and females from June to October, but the activities of SOD (except for June), POD, PPO and PAL (except for June) in male were significantly higher than those in female. [Conclusion] In the natural environment with stress factors, there was no significant differences in secondary metabolites between male and female plants. Female plants grew slower and showed lower defense enzyme activity, indicating an evolutionary trade-off between reproduction and growth and defense. Male plants of S. viminalis can be selected preferentially in practical application as they grew faster without the catkins problem. [ABSTRACT FROM AUTHOR]