Systems of oligonucleotide chemical replicator molecules provide some of the finest, empirically realizable models of prebiotic evolution. Yet, a full understanding of their eco-evolutionary implications is hampered by conflicting assumptions, modeling strategies, and therefore predictions in the literature. Here we construct a model of these systems that accounts for the reversible association of templates and copies, ultimately leading to self-inhibition and sub-exponential growth. We show that, contrary to predictions from simplified model descriptions, there are well-defined limits on the attainable diversity of different replicator species. We also demonstrate that increasing the overall concentration of the system increases diversity, but counterintuitively, an analogous increase in the available resource concentration has the opposite effect. Most notably, if an exponentially-growing replicator is also present in the system, it absorbs any increase in the total replicator concentration, while the concentrations of the sub-exponential replicators remain unchanged. In the context of prebiotic evolution, this means that in high-concentration local environments, an exponential replicator can reach disproportionately high concentrations even if its copying rate is lower than that of the sub-exponential replicators. In a variable environment, this can lead to the eventual stochastic extinction of its competitors, with the exponentially growing species taking over the community.
Sternochetus mangiferae is a pest of mangoes, occurring worldwide in regions where mangoes are cultivated. In Brazil, this insect was first detected in 2014 in Seropédica, Rio de Janeiro, and since then, various measures and studies have been conducted to contain, monitor and potentially eradicate it. Semiochemicals may provide feasible targets to develop sensitive detection and monitoring tools. Therefore, this study aimed to evaluate whether S. mangiferae use pheromones from conspecifics and kairomones from mango tree host in their chemical communication. The findings identify a blend of mango volatiles that influence the behaviour of S. mangiferae females. A synthetic blend containing the EAD-active compounds γ-butyrolactone, benzaldehyde, 6-methyl-5-hepten-2-one, myrcene, (Z)-ocimene, 2-methoxyphenol, (S)-linalool, methyl salicylate and methyl benzoate was attractive to females of S. mangiferae from Ghanaian and Brazilian populations in two-choice olfactometry experiments. The results also indicate that the absolute configuration of linalool in the mango synthetic blend is crucial for female attraction, as females respond only to blends containing (S)-linalool. Furthermore, females from both populations were attracted to the odour of live males from their respective localities. Chemical analysis of aeration samples from the Brazilian population revealed that males and females emitted qualitatively similar volatile profiles. Although no male-specific compounds could be identified to fully explain female attraction, this study provides the first evidence of intraspecific chemical communication in S. mangiferae. These findings advance our understanding of the chemical ecology of this pest and support the development of semiochemical-based monitoring and management strategies for mango orchards.
Little is known about the semiochemicals that mediate the reproductive behavior of click beetles, the Elateridae. Research over the past two decades has begun to fill this gap, with: (1) the discovery of sex attractants for a number of pest and non-pest species, and (2) subsequent studies toward development of semiochemically-based pest management approaches and conservation initiatives for pests and non-pests, respectively. We used chemical, electrophysiological, and behavioral studies to identify, synthesize, and field test female-produced sex attractant pheromones of two North American elaterid species, Melanotus piceatus and M. insipiens. We identified two possible pheromone components for each species using coupled gas chromatography-mass spectrometry analyses of extracts of ovipositors of females: (2Z,6E)-farnesyl acetate and (2E,6E)-farnesyl acetate for M. piceatus, and decyl octanoate and decyl butanoate for M. insipiens. Subsequent coupled gas chromatography-electroantennogram detection analyses indicated that antennae of males were responsive to only one of the two compounds for each species: (2Z,6E)-farnesyl acetate for M. piceatus, and decyl butanoate for M. insipiens. In field trials, (2Z,6E)-farnesyl acetate and decyl butanoate as single components attracted males of M. piceatus and M. insipiens, respectively. In both species, most male beetle flight activity occurred from May through June. Identification of the sex pheromones of these species will provide useful tools to study their biology, while further expanding our knowledge of the types of compounds to be expected in the sex pheromones of related species.
Aposematic insects often sequester plant toxins as chemical defenses, but the extent to which they selectively retain or eliminate specific compounds remains poorly understood. We investigated toxin sequestration in Danaus chrysippus, a chemically defended butterfly that feeds on the cardenolide-rich milkweed Calotropis gigantea. Using untargeted metabolomics, targeted cardenolide quantification, and Na⁺/K⁺-ATPase inhibition assays, we tested whether sequestration is compound-selective and compared the biochemical potency of plant and insect samples. Untargeted profiles showed that caterpillars and adults converge on an insect-specific metabolome, while frass retains a plant-like chemical signature. Targeted analyses showed consistent retention of four cardenolides (calotropagenin, coroglaucigenin, uzarigenin, frugoside) across developmental stages, complete exclusion of uscharin, and progressive loss of calotropin and calotoxin across metamorphosis. Enzyme assays revealed strong differences among sample types: frass showed the strongest inhibition (~ 5-fold weaker than the ouabain standard), adults were intermediate (~ 18-19-fold), and leaves and caterpillars were the weakest (~ 45-58-fold). These potency differences mirrored qualitative composition, frass contained the full set of detected cardenolides, whereas adults retained only a reduced subset. While porcine Na⁺/K⁺-ATPase assays quantify biochemical activity rather than predator deterrence, our results demonstrate clear compound-level selectivity and suggest that physiological filtering shapes the repertoire of plant toxins available for defense in aposematic insects.
The Sierra Madre Mountains, which happen to be the longest mountain range in the Philippines, is home to lush floral and faunal species as well as forest-based indigenous communities actively involved in preserving local biodiversity. With active reforestation efforts ongoing for decades, the locals are further encouraged to continue their long-standing practice of honey gathering as a form of cultural manifestation and as an important source of livelihood. To further inspire ongoing conservation efforts, we aim to show that the small molecule diversity in Sierra Madre forest honey reflects the local floral composition and is reflective of the positive impact of previous reforestation initiatives. In order to do this, liquid chromatography-mass spectrometry (LC-MS) based metabolomics was used to profile and compare metabolite diversity in honey produced by Apis cerana, Apis breviligula Maa. and Tetragonula biroi (Friese) honey from Palaui Island and Laiban in Northern and Southern Sierra Madre, respectively. Surprisingly, the Philippine National Tree and unfortunately endangered Pterocarpus indicus Willd (loc. Narra) proved to be important, especially in Palaui Island where honey from A. cerana is close to being monofloral. Aside from P. indicus and its small molecule marker hypaphorine, caffeine was detected in Palaui honey beautifully reflecting the way of life of native Agtas who manage a small coffee plantation. The abundance of caffeine, however, is higher in stingless honey samples from Tanay, Rizal where Coffea trees have been extensively included in restoration activities over the past few decades. Our results imply the possibility of using honey as an ecological monitoring tool while generating baseline chemical information that reflects the state of Philippine forests. Furthermore, the identification of unique chemical components in forest honey can be further used in programs that assist indigenous communities in safeguarding the ownership and origin of forest honey sources.
Chemical cues play an important role in mammalian communication, often reflecting an individual's physiological state. Non-invasive sampling of such informative cues holds great potential for wildlife monitoring. Endangered apex predators such as big cats are elusive and challenging to monitor. While existing monitoring techniques estimate numbers or densities, they often fail to provide crucial demographic and physiological information. We adapted a headspace solid-phase field sampling technique adapted for sampling volatiles from urine and faeces of captive Bengal tigers and Indian leopards of known age and sex, and from urine of identified wild Bengal tigers of known age, sex, and reproductive status. Volatiles extracted from these samples were analysed using Thermal Desorption- Gas Chromatography-Mass Spectrometry. The random forest algorithm was used to identify compounds that might be cues for species, age, sex, and reproductive state. Species classification accuracy was consistently high with both urine (0.79 + 0.009) and scat (0.75 + 0.029) volatiles. Classification accuracy of urine volatiles was high for females and young individuals in leopards and tigers, but lower for males and old individuals. Scat volatiles performed better across groups. We also identified putative chemical markers for epilepsy and reproductive state in tigers. This study presents the first chemical characterization of tiger and leopard scats and the first sampling of tiger odours from the wild. Our simple and cost-effective method of sampling tiger and leopard odours offers a novel method of chemical fingerprinting to monitor populations in situ. Importantly, this sampling method and analytical pipeline is broadly applicable to other mammalian species for conservation and ecological studies.
Plants available to wild herbivores, especially browsers, often contain plant secondary metabolites (PSMs). Herbivores have evolved behavioral, physiological, and microbial mechanisms for avoiding and detoxifying PSMs. The detoxification limitation hypothesis suggests that herbivores can reduce toxicity by consuming a mixture of PSMs to avoid overloading a particular detoxification pathway. Although this hypothesis has been examined for smaller mammalian hindgut-fermenters, less is known about responses to PSM mixtures in wild ruminants. To assess the role of host and microbial responses to PSM composition, we used controlled feeding trials to measure voluntary dry matter and PSM intake, urinary excretion of glucuronic acid (GA, a byproduct of PSM detoxification through conjugation), and the diversity and relative abundance of gastrointestinal bacterial families in the feces of two species of captive-raised deer (Odocoileus hemionus, O. virginianus). Deer were fed five mixtures of four purified PSMs that included two same-chemical class mixtures, two different-class mixtures, and one 4-way mixture of all chemicals. Overall, we found that PSM composition had minimal effect on intake, that GA was a consistent physiological biomarker of PSM intake regardless of PSM composition, and that dietary phenolics may influence microbial communities more than monoterpenes. Our results partially conformed to the detoxification limitation hypothesis, where deer consumed less of one same-class mixture (monoterpenes) than different-class mixtures. Our results point to the complexity of the interplay between different behavioral, physiological, and microbial mechanisms that can mediate the consequences of PSMs.
Residual kanamycin (Kana) in water bodies threatens ecological safety and human health, driving demand for straightforward and sensitive detection tools. In this work, we present a label-free electrochemical sandwich aptasensor that achieves ultrasensitive Kana detection by synergizing split-aptamer recognition with signal amplification through flower-like gold nanostructures (AuNFs). The split aptamer fragments (SPA1/SPA2) remain separate in the absence of target, minimizing background from nonspecific folding. Upon Kana introduction, a SPA1-Kana-SPA2 ternary complex assembles on the AuNF-modified ITO electrode, providing a scaffold for intercalation of the redox indicator ferrocene-naphthalimide (FND). The consequent accumulation of FND results in a markedly enhanced differential pulse voltammetry response. The three-dimensional AuNFs offer a large electroactive surface for high-density probe immobilization and efficient electron transfer. The sensor exhibits a linear response for Kana from 5 nM to 2 μM with a detection limit of 0.2 nM (3σ/k). It also shows excellent selectivity over analogous aminoglycosides, good reproducibility, and acceptable storage stability. The aptasensor was successfully applied to the analysis of real water samples, yielding recoveries of 86.4-116.8%, consistent with HPLC-MS measurements. This work provides a sensitive, selective, and reliable platform for on-site monitoring of Kana in water.
Millions of dollars and countless hours are spent on invasive plant management, and the field of invasion ecology has gained increasing attention in recent decades. Yet, despite these efforts to control and understand plant invasions, successful management is often elusive. Budgetary constraints are a common factor limiting invasive plant management programs, and therefore optimizing control strategies is essential. However, such optimization requires data on management inputs and outcomes, and these data are often missing, lacking, or underutilized. To address this knowledge gap and identify predictors of successful invasive plant control in natural areas, we examined nearly 20 years of invasive plant treatment data in the world's largest urban national park-Santa Monica Mountains National Recreation Area of southern California. We resurveyed 279 sites, which had undergone control in the past two decades, collecting data on the abundance of native and invasive plant species to evaluate long-term management outcomes. We used multiple statistical approaches to identify management inputs and site characteristics that are predictors of eradication, invasive plant cover, and native species recovery. We found that the greater the initial size or percent cover of an infestation, the lower the probability of eradication. We also found that infestations on steeper slopes and in areas that have burned more frequently are less likely to be eradicated. Promisingly, our results also showed that greater reductions in invasives generally benefited native plant communities, though not in all cases. These analyses also highlighted that persistence is key; more frequent treatments (both chemical and nonchemical) and greater investment of labor resulted in larger reductions in invasive plants. Our results highlight how site characteristics and limited resources can complicate invasive plant management, while demonstrating the value of analyzing treatment and monitoring data to identify effective control strategies and guide adaptive management decisions.
Of the > 1000 known species of North American click beetles (Coleoptera: Elateridae), sex pheromones have only been identified from a handful of species. Here, we report the identification of 5-methylhexyl (Z)-4-decenoate as the female-produced pheromone of the elaterid Elater abruptus Say (subfamily Elaterinae), a species native to the northeastern United States. The pheromone was species-specific in the geographic region where it was tested, attracting only males of the target species. Ovipositor extracts contained a number of related esters, but only two, hexyl (Z)-4-decenoate and 5-methylhexyl (Z)-4-decenoate, elicited responses from antennae of male beetles in coupled gas chromatography-electroantennogram assays. In a field experiment, traps baited with 5-methylhexyl (Z)-4-decenoate, and those baited with the blend of that compound and hexyl (Z)-4-decenoate, captured significantly more beetles than did control traps. Hexyl (Z)-4-decenoate as a single component did not attract significant numbers of beetles. This phenomenon of the production of a number of inactive analogs and homologs of a pheromone component has been reported previously for a number of other elaterid species, and it remains unclear what purpose these apparently redundant compounds may serve.
Juniperus sabina is a dominant species in the desert and mountain ecosystems. There have been reports evaluating its chemical composition and biochemical values, however, investigation on its allelopathic effect which might facilitate its dominance remains largely unexplored, with the major responsible allelochemicals undetermined. In this study, we compared the allelopathic effects of the aqueous extract, ethanol extract, as well as the essential oil (EO) of J. sabina on seed germination and seedling growth of two receiver species, the dicot plant lettuce (Lactuca sativa) and the monocot plant ryegrass (Lolium perenne). Both the extracts and the EO exhibited significant allelopathic effects, with the EO showing the strongest inhibitory effect on the receiver plants: the IC50 values of the EO, the aqueous extract and the ethanol extract on lettuce were 0.203, 2.544 and 8.142 mg/mL, and 1.042, 4.802, and 4.898 mg/mL on ryegrass, respectively; indeed, the EO completely inhibited seed germination of both tested species at a concentration of 4 mg/mL. GC/MS analysis revealed that sabinene (40.1%) and cedrol (12.74%) were the most abundant constituents of the EO. Further bioassays simulating natural conditions confirmed that volatile organic compounds (VOCs) exerted significant inhibitory effects on seed germination and root length development of tested plants. Furthermore, the EO negatively impacted the cell division of Allium sativum, suggesting that it may disrupt the cell division process to suppress plant growth. Taken together, these results suggest that J. Sabina is capable of producing active volatile compounds with allelopathic activity to inhibit seedling growth of receiver species by interfering with the cell division process, which partly explains why it is a dominant species in the communities.
Availability and quality of vegetation are critical factors influencing herbivore nutrition and population dynamics. Fourier-transform infrared spectroscopy (FTIR) offers a promising approach to analyze herbivore diets using spectral properties of phytochemicals to identify plant items. We evaluated the potential of FTIR to identify plant taxa and parts consumed by an herbivore species. Crop contents from 236 rock ptarmigan (Lagopus muta MONTIN) individuals from Iceland, collected over nine years, were separated into pure fractions of plant taxa and parts (e.g., berries, leaves) and analyzed using FTIR in the mid-IR region (4000 -400 cm⁻¹). We classified plant taxa and parts with PCA and Random Forests (RF) based on spectral signals. FTIR revealed distinct chemical fingerprints for plant taxa and parts, consistent with previously established variation in lipids, proteins, carbohydrates, and chemical defenses. RF yielded high classification accuracy for plant parts (96.7%) and moderate accuracy for taxa (85.5%), confirming the method's reliability. FTIR overcomes limitations of traditional genetic analyses by identifying plant parts with varying nutritional quality within species. FTIR provided insights into biochemical properties of plant items but could not distinguish chemically similar items. Future research should expand spectral reference libraries combining FTIR with quantification of phytochemicals and DNA metabarcoding.
A key postulate in chemical ecology is that specialist herbivore insects have evolved abilities to tolerate chemical defenses specific to their host plants. Nevertheless, past studies have shown that this assumption does not always hold true. Identifying the compounds responsible for this occasional paradigm shift is essential for improving our understanding of plant-insect interactions, and for the development of new control strategies against specialized insect pests. In this study, we examined the relationship between the chemistry of Sinapis alba L. (Brassicales: Brassicaceae) and adult feeding in Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae), i.e., a Brassicaceae specialist and major oilseed rape pest. A variation in the ability of different S. alba cultivars to resist feeding by this insect pest was exploited to identify deterrent compounds. A comparative bioassay-guided fractionation approach led to the hypothesis that sinalbin, a glucosinolate specific to S. alba and few other brassicaceous species, might deter feeding of P. chrysocephala adults. Pure sinalbin was tested at various concentrations, confirming its deterrent effect at a concentration naturally found in leaves of two-week-old plants, i.e., 15 nmol.mg- 1 FW. Such results provide new insights into host selection mechanisms of Brassicaceae specialists, i.e., that avoidance of intact glucosinolates may also contribute to preference. From an applied perspective, the identification of sinalbin as a biomarker of resistance in S. alba has the potential to guide future efforts into the development of new management strategies for oilseed rape pests such as P. chrysocephala.
This study investigated how heirloom (Cherokee Purple) and hybrid (New Girl) tomato (Solanum lycopersicum L.) plant varieties respond metabolically and biochemically to flooding and specialist (Manduca sexta) and generalist (Spodoptera exigua) insect herbivory both individually and in combination. Using LC-MS/MS based untargeted metabolite profiling of foliar tissue and solid phase microextraction and GC-MS, we characterized and quantified metabolome and aboveground headspace volatile organic compounds (VOCs) changes in response to individual and combined stressors. We additionally measured aboveground and belowground biomass in each treatment. We hypothesized that (1) flooding would dominate metabolomic reprogramming and VOC emissions; (2) specialist and generalist herbivores would elicit distinct metabolic and VOC responses; (3) single and combined stresses would produce distinct metabolite and VOC profiles; and (4) VOC emissions would differ between heirloom and hybrid tomato varieties. Flooding was the primary driver of metabolic reprogramming, VOC emission, and reduced root biomass in tomato, with accumulated metabolites linked to oxidative stress mitigation. Differences between generalist and specialist herbivory were most evident in secondary sulfur metabolites. In addition, in the heirloom tomato variety, the generalist altered many more metabolites than the specialist, a trend that was reversed in the hybrid variety. Under combined stress, flooding-induced metabolic changes were largely preserved or additive, including the accumulation of indole metabolites associated with multifunctional roles including priming plant defenses against biotic stressors, whereas herbivore-driven metabolic changes were attenuated. Monoterpenes increased under flooding and combined stress, especially in the heirloom variety. Finally, we documented varietal differences in metabolic responses reflected in increased accumulation of several metabolites in the heirloom tomato variety compared with the hybrid. Together, our results reveal that flooding, herbivory by specialist and generalist caterpillar species and their interactions can dynamically change metabolites, volatile organic compounds, and plant growth patterns and suggest that breeding history shapes plants metabolic response and resillience under multi-stress combinations.
As insect pollinators continue to decline across much of the world, understanding the factors that support them in the wild has become increasingly critical. Leafcutter bees, which are widespread and represent the first successfully managed solitary bees, require detailed knowledge of their nutrient sources, nesting materials, and nesting opportunities for effective conservation. While 'bee hotels' have been developed to provide nesting sites and nutrient resources are relatively well understood, our knowledge of the leaf sources that underpin nesting remains limited. Recent studies - though largely concentrated in North America and India - offer valuable insights into the plant species used by leafcutter bees and the ecological and biological factors influencing leaf selection. These emerging findings may prove transformative, illuminating the chemical, molecular, microbial, and biochemical mechanisms that shape leaf-foraging decisions. Such knowledge could also inform agricultural practices, enabling farmers to enhance habitats by provisioning suitable leaf sources. In this review, we examine the drivers of nesting and leaf-foraging behavior, the diversity of leaf resources, and patterns of brood mortality. We highlight research priorities that should be pursued in an integrative manner to advance the management and conservation of leafcutter bees, with particular emphasis on deepening our understanding of their sensory ecology.
As modern populations spend the majority of their time indoors, understanding indoor microbial ecology is crucial for public health. While research has addressed abiotic pollutants, the ecological dynamics of surface-associated mycobiomes remain insufficiently understood. This study assessed fungal communities across 25 types of public facilities in South Korea to evaluate the relative influence of environmental parameters and human-driven factors. A total of 327 surface samples from six surface types (handles, tables, chairs, walls, pillars, floors) were analyzed using internal transcribed spacer (ITS) sequencing, yielding 27 million reads and 31,721 amplicon sequence variants (ASVs). Although temperature and humidity significantly correlated with airborne fungal concentration, they exerted minimal influence on community diversity and structure. Instead, the intensity of human contact with indoor surfaces emerged as a primary driver of fungal community composition. We found that the relative abundance of the human-associated genus Malassezia is strongly associated with two distinct ecological states of indoor surface mycobiomes; high-Malassezia samples exhibited significantly distinct communities (ANOSIM R = 0.217, p < 0.001) and dense co-occurrence networks among genera of potential clinical relevance, with strong correlations between Malassezia and both Aspergillus and Cladosporium (|corr| = 0.81). These Malassezia-associated patterns persisting across diverse facilities demonstrate that human-driven microbes are the primary ecological drivers of surface mycobiomes in public spaces, providing foundational evidence for human contact-based microbial assessments in public health monitoring and hygiene-conscious environment design.
Fusarium verticillioides and Aspergillus parasiticus are typical fungi of stored maize. To prevail over other organisms when competing for a substrate, fungi emit volatile organic compounds (VOCs) with different bioactivities. The aim of this study was to evaluate A. parasiticus and F. verticillioides interaction in maize grains stored in silo bags at different initial humidities (iH; 7.5% or 28%) for 28 days. For each treatment, dry grain weight loss, maize fungal infection, filamentous fungi count, ergosterol content, FB1 and AFB1 content, and VOCs were determined. In silo bags, A. parasiticus caused greater surface infection of the grains compared to F. verticillioides, both individually and in co-infection. In co-infection, the number of colony forming units (CFU/ g) of both fungi decreased at 28% of iH, while at 7.5% there was only a decrease in F. verticillioides. There was greater weight loss at 28% iH and in the presence of A. parasiticus. Fumonisin B1 decreased in co-infection. The ergosterol content increased at 28% iH. Qualitative and quantitative changes in VOCs profile were observed at different iH and according to the presence of fungi. 1-octen-3-ol, 3-octanone, methoxybenzene and 2-pentyl furan were the main VOCs identified. Of these compounds, 1-octen-3-ol reduced the growth and mycotoxin production of both fungi. The 1-octen-3-ol, along with other major VOCs, may support the natural regulatory mechanism between fungi during their interaction in maize stored in silo bags.
The abuse of antibiotics has induced various environmental problems and poses a threat to human health and life. Fluorescence analysis methods have received extensive attention in the field of antibiotic detection due to their high sensitivity and specificity. However, traditional fluorescence methods are confronted with the challenges of background interference and sample complexity, and thus, there is an urgent need to develop efficient antibiotic detection methods. Herein, an efficient sample separation and enrichment method based on magnetic molecularly imprinted polymers (MMIPs) was introduced into a fluorescence biosensor for the anti-interference detection of antibiotics in water. As a proof-of-concept of our approach, chloramphenicol (CAP) was chosen as a model antibiotic to be investigated. MMIPs were synthesized using the surface molecular imprinting technology on Fe3O4 nanoparticles, achieving high selectivity and an adsorption capacity of 49.6 mg g-1. More importantly, the MMIP-assisted fluorescent probe exhibited good anti-interference ability, while the ordinary fluorescent probe was easily interfered by the coexisting substances (such as humic acid) in water, resulting in its poor detection performance. These results demonstrated the potential of MMIPs as an efficient, cost-effective tool for CAP extraction in environmental samples, offering a promising approach for the environmental monitoring of antibiotic contamination.
Carnivorous plants have evolved specialized adaptations that allow them to persist in nutrient-poor habitats, including modified traps, digestive enzymes, and mechanisms for absorbing nutrients derived from prey. Beyond these structural features, chemical signalling mediated by volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) contributes to several ecological functions, such as prey attraction, short-range interactions, and defence. VOCs can attract insects over relatively long distances, whereas SVOCs tend to remain on trap surfaces, where they may influence local interactions with arthropods and microbes. Environmental conditions, particularly precipitation and humidity, are known to affect VOC emissions and may alter foraging dynamics, yet the extent to which variation in chemical emissions corresponds with differences in prey capture is still not well resolved. To address this knowledge gap, we performed a study under both field and greenhouse conditions using the carnivorous plant Drosera rotundifolia in two climatically contrasting sites of north-western Spain: the wetter Serra do Cando (CP) and the drier Serra de Ancares (AP). At both sites, we quantified insect prey capture and characterized VOC and SVOC emissions. Prey capture rates were similar between regions, but plants from the drier site showed higher total VOC emissions, while SVOC production did not differ markedly. PERMANOVA analyses further indicated that site had no significant effect on overall VOC or SVOC composition. Together, these results suggest a balance between flexibility in emission intensity and stability in chemical composition, providing insight into how specialized metabolites support the ecological functioning of carnivorous plants across contrasting environmental conditions.
Discrimination of odorant mixtures is essential in communication and individual recognition in many animals. The number of compounds and the similarity in compound structure can, however, make discrimination challenging. An example is the use of surface hydrocarbons in ants and other social insects to differentiate between colony members and foreigners, or to identify the reproductive status of individuals. These cuticular hydrocarbon (CHC) mixtures consist of long-chain compounds, including n-alkanes, that show quantitative variability across individuals and high structural similarity. We explored the limits of discrimination in synthetic CHC mixtures in Camponotus floridanus worker ants. We used differential conditioning to determine whether workers can differentiate between heptacosane (C27) and hentriacontane (C31) alone, in binary mixtures, and in mixtures with pentacosane and nonacosane. Worker ants successfully discriminated all odor pairs in one direction with consistent responses for the mixtures across trials, regardless of whether the ratio of C27 to C31 was 2:1 or 1.33:1 or whether C27 and C31 were increased by 100% or decreased by 50% in the four-compound mixtures. Differentiation success depended on an increased C27/C31 ratio in the rewarded mixture, while workers did not differentiate when C27/C31 was high in the punished mixture. The asymmetry could be due to increased concentration, volatility, or an inherent preference for C27. The successful discrimination indicates n-alkanes could be used for nestmate discrimination and identification of reproductive individuals. The workers’ ability to discriminate among quantitative differences in structurally similar CHC mixtures demonstrates the highly accurate tuning of the ant olfactory system.