Journal of Chemical Ecology最新文献

Insect oviposition success depends on selecting optimal host plants, guided by plant chemical cues critical for larval fitness. Yet, the specific metabolites shaping egg-laying choices remain unclear, as some enhance oviposition but inconsistently affect larval performance. Since larval success is wholly contingent on adult oviposition decisions, plant metabolites mediating both egg-laying behavior and larval fitness are pivotal to understand insect behavioral ecology and targeted pest control interventions. Using Brassica specialist, Plutella xylostella, we tested the impact of plant chemical defences on oviposition and larval fitness. We used eight varieties of Brassica plants to evaluate insect oviposition preference and subsequent larval fitness. Glucosinolates, key secondary metabolites of Brassica species influenced oviposition. Among these, 4-hydroxy-indol-3-ylmethylglucosinolate (4 H-I3M) was identified to impact oviposition, larval cellular immunity and survival against entomopathogens. Larvae reared on artificial diet containing 4 H-I3M also showed higher immunity and better survival against entomopathogens. Moreover, painting 4 H-I3M on plant cultivar lacking this compound or onto a paper disc, consistently induced oviposition behavior. This study demonstrates that (a) 4 H-I3M is both necessary and sufficient to induce oviposition (b) 4 H-I3M regulates larval cellular immunity and improves survival against entomopathogens. These results suggest that insects utilize plant compounds as proactive signals, guiding their choice of host plants to enhance larval immunity and ensure survival.

Active space, the area over which a stimulus elicits a behavioural reaction in a receiving individual, is an important yet seldom investigated aspect of insect behaviour. It defines the spatial scale over which an individual interacts with a stimulus and can influence mating success and population dynamics. From an applied perspective, active space is an important component of the effective range of semiochemical-baited traps used for surveillance of forest and agricultural insects. This study used wing fanning assays, competitive trapping, and portable electroantennography to investigate the active space of spruce budworm, Choristoneura fumiferana Clemens (Lepidoptera: Tortricidae) and spongy moth, Lymantria dispar dispar L. (Lepidoptera: Erebidae) pheromone-baited traps. Wing fanning assays and competitive trapping had similar outcomes for active space distance for both species. For spruce budworm, wing fanning assays estimate an active space of 18.4 m and competitive trapping experiments showed interference at distances less than 20 m. For spongy moth, wing fanning assays suggest an active space of 81.5 m, corroborating results from a previous study that estimated trap interference to occur at distances less than 80 m. Portable electroantennography displayed an increase in neural depolarization amplitude at distances less than 30 m for spruce budworm and 130 m for spongy moth. Overall, the three methods used showed similar results for the active space distance of each species.

Mosquitoes of the genus Aedes, including the invasive Aedes albopictus, are responsible for the transmission of arboviruses such as dengue, chikungunya, and Zika. Their global expansion has intensified public health concerns, while the efficacy of insecticide-based control is declining due to resistance and environmental risks. These limitations have increased interest in odor-baited traps as complementary tools for surveillance and population reduction. Yet, their performance in the field remains inconsistent, largely because lures rely on a restricted set of human skin microbial volatiles and capture mainly host-seeking females. This review highlights the contribution of microorganisms inhabiting human skin and floral nectar to mosquito feeding ecology. Skin microbiota shape odor profiles by producing volatile organic compounds that mediate host attractiveness and species-specific mosquito responses. Likewise, nectar-dwelling yeasts and bacteria alter nectar chemistry and floral scent, generating volatiles that influence insect foraging, although their role in Aedes attraction remains poorly studied. By integrating data from Aedes and other insect models, we highlight microbial semiochemicals with demonstrated or potential roles in guiding blood- and sugar-feeding behaviors. We further discuss how microbial ecology, compound concentration, and chemical interactions drive variability in mosquito responses, raising both opportunities and challenges for trap design. Expanding research to nectar-associated microbial cues, while considering ecological specificity and possible non-target effects, could help create more versatile lures that attract both sexes and multiple feeding stages. This review advances our understanding of microbial-associated cues as critical drivers of mosquito behavior and outlines future directions to improve odor-based surveillance and control of Aedes vectors.

Citrus rust mite (Phyllocoptruta oleivora Ashmead) (Acari: Eriophyidae) (CRM) is a significant biotic stressor affecting citrus fruit quality by damaging the peel and inducing physiological and chemical alterations. This study explores the dual impact of mite infestation on the pomological traits and peel phytochemistry of Citrus sinensis (orange), with a focus on polymethoxyflavones (PMFs), a class of secondary metabolites associated with plant defense. Oranges with varying levels of visible CRM injury (INJ1 to INJ3) were compared to uninjured controls. Morphological analysis revealed significant reductions in fruit weight, size, peel thickness, and juice content with increasing injury severity, while total soluble solids (TSS) increased moderately. Phytochemical profiling of peel extracts obtained by subcritical water extraction and supercritical CO₂ extraction indicated a notable rise in PMFs content-from 3.8% in control samples to 9.5% in the most severely injured group. These biochemical and morphological changes together represent distinct stress fingerprints associated with CRM. Our results demonstrate that CRM infestation elicits a multifaceted plant response, simultaneously impairing physical fruit traits and activating secondary metabolism. The accumulation of PMFs in damaged peel suggests an induced defense mechanism that may serve as a biochemical marker of herbivore stress. These findings underscore the importance of integrating chemical ecology perspectives into citrus pest management and provide new insights into host-arthropod interactions in perennial crop systems.

Secondary metabolites are critical to plant defenses and frequently exhibit variation among populations associated with heterogeneous climatic factors and/or herbivore communities. We examined genetic-based geographic and ontogenetic variation in phenylpropanoid glycoside (PPG) concentrations and arsenals in Mimulus moschatus, a perennial monkeyflower native to western North America. We conducted a greenhouse common garden with maternal lines collected from three populations sampled along a latitudinal gradient paralleling spatial sampling from a previous study in the closely related congener, Mimulus guttatus. We assessed PPG arsenals as well as concentrations of individual and total PPGs within leaf tissue from two developmental stages. Populations differed in total concentration and arsenal composition of PPGs, with the populations from intermediate latitudes exhibiting higher concentrations than higher and lower latitude populations. Leaves from earlier developmental stages had higher overall PPG concentrations than leaves from later developmental stages across all populations, suggesting juvenile tissue is better defended than more mature tissue. Spatial patterns in relative PPG concentrations and arsenal composition tightly paralleled those in the closely related M. guttatus across space despite consistently lower total PPG concentrations in M. moschatus. Because we did not measure herbivory and our sample size is limited, these results should be interpreted cautiously. Nonetheless, they provide baseline data for understanding geographic and developmental variation in chemical defenses and generate hypotheses about environmental influences and potential convergence in defenses among closely related species.

This study reports the physiological effects of the invasive alien species Batophora occidentalis within a small lagoon in the Balearic Islands. This study aims to determine whether the presence of newly colonizing invasive macroalgae causes physiological effects on the sessile Porifera species Sarcotragus spinosulus through the application of biochemical markers and metabolomic fingerprinting. Sections of 27 different individuals were collected at three representative sites (N = 9 in each site) of varying degrees of epibiont colonisation (high, low, and absent). The activation of antioxidant enzymes for catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRd) was observed between individuals that were highly affected by B. occidentalis in addition to the detoxification mechanism for glutathione s-transferase (GST). In terms of oxidative damage, MDA levels were found to be nonsignificant, although those individuals characterised by high epibiont colonisation reported higher levels than those in areas where B. occidentalis was not present. Furthermore, significant differences were observed in the metabolomic fingerprinting of the different levels of epibiont colonisation, an indication B. occidentalis is causing changes in chemical and metabolomic characteristics in S. spinosulus. These findings highlight the need for targeted conservation strategies to mitigate the ecological impact of this invasive species in Mediterranean coastal lagoons.

Asecodes hispinarum (Hymenoptera: Eulophidae) is an endoparasitic wasp and efficient biological control agent of the coconut leaf beetle, Brontispa longissima, a significant pest of more than 20 palm species. Due to its effectiveness against B. longissima, A. hispinarum is extensively utilized in the pest management of palms such as coconut, betel nut, and oil palm. Olfaction plays a crucial role in insect behaviors such as finding food, selecting oviposition sites, and locating mates. Despite the critical role of olfaction in host-seeking behavior, the molecular basis of chemoreception in A. hispinarum remains unexplored. In a previous study, we identified several olfaction-related genes in A. hispinarum through transcriptome sequencing and bioinformatics analysis. In the current study, the chemosensory protein gene 1 (AhisCSP1) of A. hispinarum was cloned, and real-time PCR was employed to assess the expression levels of AhisCSP1 across different developmental stages and adult tissues in A. hispinarum. Additionally, the odorant binding characteristics of AhisCSP1 were examined using in vitro protein expression technology and fluorescence competitive binding assays. The real-time PCR results indicated that AhisCSP1 was expressed at all developmental stages, with higher expression levels in the adult stage compared to other stages. Furthermore, AhisCSP1 expression was specific to (A) hispinarum antennae, with no expression detected in the head, thorax, abdomen, legs, or wings. A fluorescence competitive binding assay revealed that AhisCSP1 can effectively bound to the coconut volatiles L-α-terpineol, benzyl alcohol, 3-phenylpropionic acid pentyl ester and 2-ethyl-1-hexanol, with binding constants of 21.26, 25.42, 27.96, and 39.72 µmol/L, respectively. Among the four volatiles of (B) longissima larvae, AhisCSP1 demonstrated a strong binding capacity with isohexadecane, with a binding constant of 19.76 µmol/L, a medium binding capacity with pentadecane, with binding constant of 34.28 µmol/L, and a weak binding capacity with butyl benzoate and methyl eugenol, with binding constants of 53.45µmol/L and 58.27µmol/L, respectively. These findings suggest that AhisCSP1 may play a dual role in (A) hispinarum's host location by sensing the volatiles from both its host, (B) longissimi and the host habitat, i.e. palm species. Furthermore, these results suggest that AhisCSP1 could be a potential target for enhancing biological control strategies against B. longissima.

Flowering plants attract pollinators via traits such as floral scent and morphology, which are often influenced by other interactions like herbivory. However, the effects of herbivory on floral traits may not be consistent across traits, resulting in changed relationships between multimodal traits that could alter pollinator perception. We investigated how herbivory affects floral scent and morphology, and alters correlations between signaling traits. In a natural community, we simulated herbivory seven days before flowering on eight Asclepias syriaca (common milkweed) plants by removing half of their foliar tissue and applying a jasmonic acid solution; eight additional plants received a control spray with solvent only and no damage. After treatments, we collected floral volatile organic compound (VOC) emissions (i.e., scent) and measured five floral morphological traits on all plants. We found that simulated herbivory significantly altered VOC composition. Additionally, herbivory increased flower diameter and hood width while decreasing hood height, but had no effect on inflorescence size, measured as flower number or dry mass. Notably, we found that simulated herbivory led to significantly stronger correlations in floral traits, including both flower morphology-VOC correlations and VOC-VOC correlations. This study demonstrates that herbivory induces changes in floral morphological traits and VOC emissions and increases correlations between floral traits. These findings highlight how herbivory can interfere with the floral traits that plants use to signal their pollination partners.

Lycorma delicatula is a polyphagous phloem feeder, which is spreading rapidly in the U.S., and is a major threat to grapes, hops, and ornamentals. Among its hosts, L. delicatula prefers Ailanthus altissima, an invasive tree from which it sequesters toxins, including several quassinoid compounds. We tested how these defenses affected predation by birds of nymphal and adult L. delicatula. Freeze-killed nymphs of each instar were reared with or without access to A. altissima and placed into cups on top of nest boxes occupied by house wrens (Troglodytes aedon). House wrens ate or fed their chicks a greater proportion of L. delicatula nymphs that had not had access to A. altissima than the nymphs that had access to this host plant. Adult L. delicatula reared with or without access to A. altissima were ground up and incorporated into separate batches of suet that were placed into double sided feeders set up at different sites during the winter. Trail camera video was reviewed to record how many times birds pecked each suet cake. Birds pecked the suet containing L. delicatula reared without access to A. altissima significantly more frequently than the suet containing adults that had fed on A. altissima. Of the quassinoids sequestered by L. delicatula from phloem sap of A. altissima, ailanthone and four other quassinoids were identified and quantified in different tissues, with the highest concentrations in the salivary glands. Results suggest that sequestration of toxic chemicals from A. altissima provides some protection to L. delicatula from avian predators.

Wildfires are increasingly affecting boreal conifer forests, altering their chemical defences and carbohydrate reserves in ways that may affect their susceptibility to subsequent herbivore threats. We quantified monoterpenes and non-structural carbohydrates in the phloem of lodgepole pine across three treatments (unburned, burn-year, one-year post-fire) to identify fire-induced chemical changes and their temporal dynamics. Monoterpene concentrations rose sharply immediately following the fire but declined after one year. Non-structural carbohydrates showed compound-specific responses: starch and sucrose concentrations reduced post-fire, with partial recovery of sucrose, while glucose increased, and fructose exhibited a delayed response. Multivariate analysis revealed sucrose, starch, and specific monoterpenes as key compounds distinguishing the treatments. Elevated monoterpene concentrations immediately post-fire likely decreased susceptibility to insects; however, the subsequent decline in defences and accumulation of sugars suggest the emergence of a distinct post-fire window of increased vulnerability. These findings improve our understanding of fire-induced chemical shifts and can help predict forest vulnerability to interacting biotic stressors under a changing climate.