Chemoecology最新文献

In flammability assessment, the terpene effect is usually studied using their total or subgroup content, missing, therefore, the information that could be provided by the molecules themselves. In this study, the specific role of terpenes on leaf flammability was sought comparing different levels of terpene identification—total, subgroup (i.e. mono-, sesqui-, and diterpene), and single compound—as well as their interactions with fuel moisture content (FMC) in four species common in Mediterranean Wildland–Urban Interfaces (Pinus halepensis, Cupressocyparis leylandii, Hesperocyparis arizonica, Cupressus sempervirens). Pinus halepensis was the most flammable species (low FMC and higher sesquiterpene content but low terpene diversity) while Cupressocyparis leylandii presented the highest terpene diversity and total terpene content (higher mono- and diterpene content). Flammability was differently affected according to the terpene identification level used in the models. The effects ranged from non-significant for most species studied, using subgroup or total terpene content, to mostly significant, using single compound content. Regarding the former, the lack of significant results could be due to opposite effects of different single compounds within a terpene subgroup. For the latter, terpene molecules driving flammability and their effects (positive or negative) differed among species. A cumulative effect with FMC was also highlighted in some cases but terpenes mostly remained the main flammability drivers regardless of the species. Using the refined terpene level in modelling allowed a better understanding of the compounds’ role on flammability, which is useful in the identification of plant traits linked to flammability.

Plants that naturally accumulate aluminium (Al) may also inadvertently accumulate rare earth elements (REEs) due to the similar chemical properties of Al and REE trivalent ions, and vice versa. In this study, an Al hyperaccumulator plant species, Melastoma malabathricum, and a species known to have a propensity to hyperaccumulate REEs (in addition to Al), Dicranopteris linearis, were evaluated for potential REE accumulation in a one-year pot dosing trial in Sabah, Malaysia. To test whether the Malaysian accessions of D. linearis and M. malabathricum hyperaccumulate REEs (and Al), both species were grown in pots containing soil treated with solutions containing yttrium (Y), lanthanum (La), neodymium (Nd), and a mixture of these three REEs. The results showed that both M. malabathricum and D. linearis accumulated > 1000 µg g⁻¹ Al in their leaves as expected. The shoots of M. malabathricum contained lower REEs than the roots (50 µg g⁻¹ compared to 905 µg g⁻¹). In D. linearis, the mean foliar REE concentrations ranged from 145 to 315 µg g⁻¹, which is below the hyperaccumulation threshold set for REEs (> 1000 µg g⁻¹ REEs). This study revealed that the Malaysian accessions of both M. malabathricum and D. linearis are Al hyperaccumulators, but their REE hyperaccumulation status requires further testing.

Two components of the Synanthedon bicingulata sex pheromone, (E,Z)-3,13-octadecadienyl acetate (E3,Z13-18:OAc) and (Z,Z)-3,13-octadecadienyl acetate (Z3,Z13-18:OAc), were synthesized to investigate the effect of pheromone blends, trap type and trap color on the capture of S. bicingulata males. The optimal sex pheromone ratio for E3,Z13-18:OAc and Z3,Z13-18:OAc was approximately 4.3:5.7 based on the purity of the two pheromone components in all test areas. A significant difference was observed in the number of S. bicingulata adult males caught in bucket and delta traps. The mean numbers of males caught in bucket and delta traps were 13.2 ± 2.2 and 7.6 ± 2.0, respectively. Trap color affected the number of adult males caught in bucket traps. More adult males were attracted to a yellow bucket trap than to green, white, blue, black and red traps. An analysis of the relationship between trap capture and trap surface-color values (L*a*b*) revealed a positive relationship between trap capture and b* value.

Endophytic fungi have the potential to enhance plant resistance to various stresses and promote the ecological adaptation of the hosts. To evaluate the effects of the riparian endophytes on rice seedlings to flooding tolerance, here we screened out two fungi from the plant Myricaria laxiflora growing in the Yangtze River zone. Through morphological characteristics and rDNA ITS (internal transcriber region) sequence, the two strains were, respectively, identified as Aspergillus fumigatus and Chaetomium globosum. Metabolites derived from both fungi were capable of increasing tolerance of rice to flooding. Systematic separation and purification coupled to bioassays revealed that two natural antioxidants, Z-N-4-hydroxystyryl formamide (NFA) and chaetoglobosin A (CheA), were effective for alleviating flooding stress. Both NFA and CheA can reverse the decline trend of oxidative parameters caused by long-term flooding, such as malondialdehyde, superoxide dismutase, ethanol dehydrogenase, and NADPH oxidase. Gene expression analyses of NADPH oxidase families indicated that OsRbohB could be involved in conferring flooding tolerance mediated by the two natural antioxidants. These findings contribute to understanding the role of the natural antioxidants in riparian endophytic fungi and providing a basis for improvement of flooding tolerance of rice and other crop plants.

Free-ranging giant pandas (Ailuropoda melanoleuca) in China recently were reported to rub and roll in horse manure, a behavior that was observed frequently at low ambient temperatures. Two sesquiterpenes, β-caryophyllene (BCP) and caryophyllene oxide (BCPO), that are abundant in fresh horse manure elicited rolling in captive giant pandas. Mice and rats treated with BCP/BCPO exhibited enhanced cold tolerance in behavioral assays, and BCP/BCPO inhibited cold-activated ion channels of mammals expressed in human kidney cells; these laboratory results were cited in support of the contention that giant pandas tolerate low ambient temperatures by applying horse manure to their integument. The demonstrated biocidal activities of BCP and BCPO against insects and ticks, and the reported elicitation of anointing in giant pandas with materials other than horse manure, including substances or constituents thereof known to act as arthropod biocides, are consistent with an anti-consumer function of anointing by giant pandas. Anointing with the scents of heterospecifics as a defense against nuisance arthropods constitutes a viable hypothesis for the rubbing and rolling behaviors of giant pandas and other ursids.

Insects in several orders deposit marking pheromones following oviposition. In addition to preventing the female from visiting the same site again, the pheromone also signals the presence of eggs to conspecific females. This form of chemical marking is particularly prevalent in species which oviposit on discrete hosts with limited resources available for developing larvae. The pepper weevil is a major pest of cultivated pepper throughout the southern United States, Mexico and the Caribbean. The weevil deposits eggs singly in a cavity chewed in flower buds and small fruits and caps these cavities with a plug derived from an anal secretion. The deterrent was found to be located in this oviposition plug and comprised of volatile and contact-acting components. Plug volatiles were collected by inducing oviposition into Teflon tape sachets containing pepper leaves and collecting volatiles from plugs laid on the tape surface. Of the two major components observed by GC/MS analyses, only acetophenone elicited a behavioral response by the female weevil in small arena and wind tunnel assays. Investigations of the oviposition plug matrix identified several free unsaturated and saturated fatty acids as major constituents of the plug which was in stark contrast to pepper tissue and seeds that contained only trace levels of free fatty acids and a distinctly different total fatty acid composition. The combined free fatty acids as well as acetophenone tested singly gave no significant reduction in oviposition while a plug-mimicking blend of unsaturated fatty acids tested in combination with acetophenone as artificial ‘plug spots,’ decreased oviposition on treated peppers by up to 75%. We propose that the combination of volatile and contact acting marking components improves oviposition site selection efficiency by pepper weevils on discrete hosts.

In this work, we discussed and counter-commented Paul J. Weldon's comments on our recent paper (Zhou et al. Proc Natl Acad Sci USA 117:32493, 2020a), where we reported that BCP/BCPO (beta-caryophyllene/caryophyllene oxide) in fresh horse manure is sufficient to drive manure rolling behavior (HMR) in giant panda and attenuate the cold sensitivity of mice by directly targeting and inhibiting transient receptor potential melastatin 8 (TRPM8), an archetypical cold-activated ion channel of mammals. The main question we arise in this response is: “which is the reasonable target of BCP/BCPO? Parasites or TRPM8?” Based on the knowledge of TRPM8-mediated cooling sensation, interaction between BCP/BCPO and TRPM8, BCP/BCPO concentration in horse manure samples, correlation between HMR frequency and habitat temperature, insecticidal activity of BCP/BCPO and thermal ecology of parasites, we prefer a simple idea that BCP/BCPO-induced TRPM8 antagonism bestows the wild giant pandas with cold tolerance at low-ambient temperatures. Compared with the speculation of insecticidal activity induced by HMR behavior, our study provided a comprehensive mechanism to confirm a physiological target of BCP/BCPO during the highly cold-correlated behavior.

A variety of models have been used in mating bioassays of insects to assess the contribution of chemical and visual signals to mate location and mate selection. Although the use of such ‘dummies’ has had varying degrees of success, some insect species refuse to accept simplistic models. In the present study, we developed a 3D-printed model to explore whether more realistic models will be more successful than simplistic models in mating assays of difficult to manipulate species such as the flea beetle Altica fragariae. We ran five experiments to test (1) whether males could discriminate between males and females solely based on differences in cuticular hydrocarbons (CHCs), (2) whether males use shape or (3) color to choose mates, and (4) whether males can discriminate between 3D-printed models and freshly killed beetles either with or (5) without legs and antennae. The results of these experiments confirmed that male A. fragariae preferred models coated with CHCs of females over that of male CHCs, providing strong support for the role of CHCs in mate choice in Altica. We also showed that males use both shape and color in mate selection, and that males are capable of discriminating between the models and real beetle specimens. Together, the results indicate that 3D-printed models can provide a feasible and cost-effective method for mating studies of insects.

In insects, chemical communication is the most common form of communication, and cuticular hydrocarbons (CHCs) are employed in recognition processes. In social insects, CHCs also help define colony identity and thus contribute to social cohesion among nestmates. Individuals can deposit their chemical signatures on nest surfaces. This information serves as a reference for newly emerged individuals and allows them to obtain the odor specific to their colony. This study examined nest chemical profiles in an inbred invasive species: the yellow-legged hornet, Vespa velutina nigrithorax. We demonstrated that nest structures (i.e., envelopes, combs, and pillars) had specific hydrocarbon profiles, which were colony specific. There were similarities between the chemical profiles of the nests and the CHC signatures of hornets. The loss of genetic diversity previously documented in the yellow-legged hornet population in France does not appear to have constrained nest chemical diversity.