Chemoecology最新文献

Semiochemicals released by predators (i.e. “kairomones”) may be useful for prey species. Knowledge on functional use of olfaction to detect kairomones and the consequent antipredator behaviour remains scant in birds, especially in raptors. The study population of Eurasian kestrels Falco tinnunculus canariensis inhabits the island of Tenerife, and man is one of its main predators, destroying clutches and stealing nestlings. Man and kestrels have evolved in sympatry or, at least, have been sharing the habitat for a long time. Parent kestrels were exposed to chemical cues: human fresh urine (predator), cologne (odorous control), or water (odourless control) in the nest when provisioning for nestlings. They did not display clear signs of aggressive antipredator behaviour when in contact with kairomones released by a non-present human predator. With human urine, they visited less, arrived earlier the first time in the trial, but their refusal percentage dropped significantly, and they spent more time inside the nest than those containing cologne or water. Females, especially, visited those nests highest above the ground less times regardless of substance. Interactions among some environmental (e.g. nest height, variations in human urine odour) and behavioural factors (e.g. neophobic response) could influence kestrel behaviour regarding kairomones. Kestrels would exhibit commensurate responses according to the magnitude of predation risk faced. We suggest kestrels do not ultimately react through behavioural defence mechanisms based on chemical cues from human predators, although it remains unclear if they respond to these chemical cues in other ways.

Purposeful manipulation of biological control programs, such as timed releases of biological control agents, can be ephemeral and difficult to expand into new areas impacted by the targeted invasive plant. Integration of chemical ecology through attractive semiochemical lures to aggregate biological control agents to un-colonized areas can help mitigate this challenge. The invasive air potato vine, Dioscorea bulbifera L., is native to Asia and Africa with invasive infestations in the southeastern United States, Hawai’i, and Puerto Rico. In 2011, a host specific biological control agent, Lilioceris cheni (Coleoptera: Chrysomelidae), was introduced to manage D. bulbifera. Synthetic and racemic blends of previously identified attractive herbivory induced plant volatiles (HIPVs), ocimene and farnesene, were first evaluated for antennal response through electroantennography, then deployed as potential attractive lures in field conditions. Electroantennogram results validated the ability of adult male and female L. cheni to detect the two compounds. When used in field conditions, adult L. cheni beetles showed increased response to plants with ocimene and farnesene lures compared to control plants. The chemically enhanced lures increased L. cheni adult densities on D. bulbifera plants in the field compared to control plants. Plants with higher densities of L. cheni had greater direct herbivore feeding damage and observed cupped leaves, indicating the presence of oviposition and future larval development. The information gathered in this study indicated that the use of attractant semiochemical lures to purposefully aggregate and direct movement of biological control agents can improve the efficacy of invasive plant biocontrol programs.

The alpine grasshoppers Sigaus nivalis, Sigaus australis and Sigaus nitidus are sympatric in the central mountains of South Island, Aotearoa New Zealand. These grasshoppers feed on a range of alpine plants but show preference towards dicots over monocots. Because herbivorous insects often use smell and taste to locate and recognize food plants it was expected that these grasshoppers would show sensitivity to their favorite foods and potential sensitivity to nonhost plants. Here, we determined feeding preference in captivity allowing each of these three sympatric grasshoppers the same choice of six native alpine plant species. We analyzed the chemical compositions of the plants used in these experiments using gas-chromatograph coupled with mass-spectrometry (GC-MS) and then recorded olfactory responses in the grasshoppers to plant-derived smells (with synthetic compounds) using electroantennogram (EAG). The grasshoppers were able to distinguish between the potential food plants and ate the shrub Coriaria sarmentosa but not the grass Chionochloa pallens, however, the chemicals we detected in the six plant species were very similar. High sensitivity to fatty acid derived aldehydes (decanal, (E,Z)-2,6-nonadienal, hexanal) and a 6-carbon alcohol ((Z)-2-hexen-1-ol) compared to terpenoids (α-phellandrene, β-myrcene, β-ocimene, eucalyptol, (S)-(-)-limonene, (1S)-(-)-α-pinene) or an aromatic compound (2-phenylethanol) was recorded in the antennae of all three grasshopper species and no species- or sex-specific sensitivity to particular compounds was observed. As aldehydes and alcohols are emitted upon plant damage, it is possible that these generalist grasshoppers are sensitive to the smells of damaged plants rather than species-specific plant smells.

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.

During field screening trials in Brazil, adults of both sexes of the cerambycid beetle Achryson surinamum (L.) (Cerambycinae: Achrysonini) were significantly attracted to racemic anti-2,3-octanediol, previously identified as a sex and aggregation-sex pheromone of various cerambycid species across different continents. Analyses of beetle-produced volatiles revealed that males of A. surinamum sex-specifically produce (2S,3R)-2,3-octanediol, as well as lesser amounts of (S)-2-methylbutan-1-ol. In field trials, both sexes of beetles were attracted by reconstructions of the species’ pheromone blend with synthesized components, confirming males produce an aggregation-sex pheromone. During the trials, the cerambycine Sphaerion inerme White (Elaphidiini) was attracted to some of the test lures, providing leads to its attractant pheromone. Subsequent analysis of extracts of headspace volatiles from live adults of S. inerme revealed that males produce a blend of (R)-2-methylbutan-1-ol and (R)-2-methylpentan-1-ol. In field tests, blends of racemic 2-methylbutan-1-ol+2-methylpentan-1-ol attracted significant numbers of beetles of both sexes. This study provides further examples of how identification of attractant pheromones of cerambycid species can be expedited by leveraging prior knowledge of the pheromone chemistry of related species.

The problem of persistent and potentially toxic heavy metal-contaminated soils is widespread worldwide. These heavy metal concentrations have continued to accumulate in soils over the past three decades, posing a threat to the environment and human health. Therefore, the problem of heavy metal soil contamination needs to be addressed urgently. In this paper, we describe the sources of heavy metal pollution and their hazardous properties, emphasizing the urgent need for treatment. Traditional remediation techniques for heavy metal contamination include physical, chemical, and biological methods. Each of these methods has its advantages and disadvantages and can be combined to remove (transform) or reduce heavy metals in contaminated soils to safe levels. The article provides a comparative analysis of traditional remediation techniques for heavy metal contamination, focusing on a review of the current status of research and application of microbial remediation methods in heavy metal contamination of mine soils. The paper also discusses the combined microbial and chemical/plant remediation techniques. In conclusion, the remediation and treatment of heavy metal-contaminated soils should consider both the economy and effectiveness of the remediation technology. Microbial remediation is a typical remediation technology that will become the main development trend due to its effectiveness and low cost.

Millipedes of the order Glomerida are known to produce quinazolinone alkaloids as defensive substances. However, chemical data are rather scarce and all hitherto available publications refer to a single glomeridan family, the Glomeridae. To contribute to the knowledge of the chemical ecology of glomeridans, we collected species, Typhloglomeris coeca Verhoeff, 1898 and T. varunae Makarov, Lučić, Tomić & Karaman, 2003, from a second family – Glomeridellidae. The defensive exudates were extracted in methylene chloride and analyzed by gas chromatography-mass spectrometry. Our results show that the secretions of the two glomeridellids contain the quinazolinone alkaloid homoglomerin (2-ethyl-1-methylquinazolin-4(1H)-one) as the sole defensive constituent. This report provides initial data on the chemoprofiles of members of the family Glomeridellidae and supports the phenomenon of chemical homogeneity of glomeridan defensive secretions. So far, all analyzed representatives of the order possess glomerin and/or homoglomerin as defensive equipment. The phylogenetic origin of alkaloidal compounds in the secretions of millipedes in general, and particularly the origin of quinazolinone alkaloids in Glomerida is discussed. Considering that the quinazolinone alkaloid defensive secretions may be the same (or very similar) in other Glomerida, our results have important implication for further studies of defensive secretions in these arthropods. Also, as data are available only for a limited number of glomeridan and colobognathan species, additional analyses are necessary to elucidate the evolution of alkaloid defensive secretion in Diplopoda.

Lygus hesperus Knight is a polyphagous pest of major concern to numerous cropping systems across western North America. Lygus hesperus exhibits well-documented host preferences which may be used to develop behavioral management strategies for this pest. This study sought to identify plant volatiles that mediate L. hesperus host preferences and assess the potential of those compounds to improve monitoring and management of this pest. Gas chromatography with electroantennographic detection was applied to identify antennally active compounds in headspace extracts from four host plants of varying attractiveness. Y-tube olfactometer assays were then conducted to determine L. hesperus responses to each of these 17 antennally active compounds individually. Six compounds attracted female L. hesperus, and subsequent tests revealed that females were attracted to an equal-parts blend of these six attractive compounds versus clean air, and that this blend was as attractive as flowering Medicago sativa. We then examined L. hesperus attraction to attractive compounds individually and an equal-parts blend of five attractive compounds in the field. An equal-parts blend of five attractive compounds was tested in strawberry, whereas the blend and each individual component were tested in alfalfa. In both field settings, neither the individual compounds nor the blend increased L. hesperus capture rates compared to unbaited control traps. Low attraction in the field could result from a masking effect of background volatiles or the failure to include important compounds in tested blends. It remains important to assess whether the compounds tested in this study may facilitate L. hesperus management in other cropping systems.

Mistletoes are adapted to parasitize aerial parts of their hosts, and they have a great morphological variation and wide global distribution. Their effects on hosts were more or less investigated; however, no comparative interspecific study had been reported. This study aimed to compare three locale mistletoes Phragmanthera austroarabica, Viscum schimperi, and Plicosepalus acacia based on photosynthetic activity, major-trace- and ultra-trace elements’ distribution and metabolome profiling. P. acacia exhibited the highest net photosynthetic assimilation rate (3.3-folds), water use efficiency (5.5-folds), and accumulated major elements (⁴⁴Ca, ²⁴Mg, and ²³Na). Equally, the untargeted metabolomic method showed a substantial difference in metabolome profiling, with P. acacia being the lesser accumulative of major metabolites than P. austroarabica and V. schimperi. Based on the few identified common metabolite analysis, P. acacia had the ability to avoid the accumulation of the pollutant mono(2-ethylhexyl) phthalate which, P. austroarabica and V. schimperi, cannot do. Equally, P. acacia had more defence metabolites against stressors than the other mistletoes. Accordingly, P. acacia displayed higher potentialities to be more vigor and more adapted to the parasitism’s life than P. austroarabica and V. schimperi.

Pheromones play a pivotal role in coordinating collective activities. Recent research has demonstrated that workers of the Japanese subterranean termite, Reticulitermes speratus, secrete an aggregation pheromone that induces quick assemble and prolonged stay at the pheromone source for nestmate workers, facilitating efficient dead-wood digestion and colony expansion. The question remains: do other termite species also utilize aggregation pheromones? In this study, we report that workers of the Formosan subterranean termite, Coptotermes formosanus, use a mixture of fatty acids as part of the pheromone components to maintain worker aggregation for extended periods of time. Through bioassays and gas-chromatography mass-spectrometry (GC–MS) analysis, we determined that a mixture of four fatty acids including palmitoleic acid, palmitic acid, (Z)-10-heptadecenoic acid, and stearic acid possesses arrestant activity but little or no attractant activity. Also, the inclusion of cholesterol and cuticular hydrocarbons reinforces only its arrestant activity. Further, GC–MS analysis of extracts of wood and soil, which serve as termite food, indicated that the pheromone components other than palmitic acid are not derived from their food, and GC analysis of extracts from different parts of the worker’s body revealed that these components were most likely produced in the midgut and excreted to the outside of the body via the hindgut. These findings suggest that the aggregation pheromone components and their functions in C. formosanus are largely different from those in R. speratus. This research provides insights into the differences among termite species in the development of chemical signals triggering aggregation behavior.