Chemoecology最新文献

The Coffee Berry Borer (CBB) Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) is an important pest species that has invaded all major coffee-producing areas of the world, causing tremendous economic losses every year. Since its discovery on the island of Jamaica approximately 40 years ago, the beetle has moved from lowland regions with comparably warm and dry climates to higher altitudes with cooler and wetter conditions in the Blue Mountains. Some insects have been shown to react to such environmental variation with changes in their cuticular hydrocarbon (CHC) profiles. To investigate if this is also the case in CBBs, we characterized the CHC profiles of beetles collected from different farms varying in altitude and climate across Jamaica and from one farm in Panama. We found that the CHC profiles of CBBs are mainly composed of straight-chain alkanes and methyl-branched alkanes, and that differences in farm location or rearing conditions (lab or field) may not necessarily result in CHC variation. The coffee berries provide a microclimate which protects the beetles from the conditions outside the coffee berries for the majority of their life cycles, thus potentially buffering this major pest from external environmental selection pressures.

This study investigates the herbicidal potential and mechanisms of four volatile terpenoids—1,8-cineole, citral, menthone, and geraniol—against the weeds Amaranthus viridis and Chenopodium murale. All compounds exhibited significant allelopathic effects in a dose-dependent manner. Notably, 1,8-cineole and citral strongly inhibited seed germination, shoot, and root growth, with C. murale showing higher sensitivity than A. viridis. Geraniol had the most potent effects on C. murale with IC₅₀ values of 2.25, 2.27, and 7.10 mg/L for seed germination, shoot growth, and root growth, respectively. Menthone was most effective against A. viridis with IC₅₀ values of 31.50, 27.24, and 19.81 mg/L for germination, shoot growth, and root growth, respectively. Molecular dynamics and Molecular Mechanics Generalized Born Surface Area (MMGBSA) studies confirmed these terpenoids as transport inhibitor response 1 (TIR1) antagonists, suggesting their potential as natural herbicides targeting auxin pathways. Further research is needed to assess their ecological impact and practical application.

Rhyssomatus nigerrimus (Coleoptera: Curculionidae) is considered an economically important pest of soybean cultivation in Mexico and is attracted by floral odour of soybean. R. nigerrimus has been observed in some inflorescences of alternative host plants that serve as refuge and food when the soybean plant is not seasonally available. The aim of this study was to determine which volatiles emitted by inflorescences of Hamelia rovirosae and Lantana camara, alternative host plants of the weevil, mediate the attraction of R. nigerrimus. We collected the volatiles from both inflorescences by dynamic aeration and analyzed them with gas chromatography coupled to mass spectrometry, performed behavioral bioassays in a Y-shaped olfactometer, and performed electroantennographic measurements. We identified monoterpenes, sesquiterpenes and fatty acid derivatives (ketones, alcohols) in the two species, with α-pinene, β-caryophyllene and 2-ethyl-1-hexanol being most abundant in H. rovirosae, and α-pinene, β-caryophyllene and α-copaene being most abundant in L. camara. The volatiles from the inflorescences, individual compounds and a blend of synthetic compounds elicited antennal and attraction responses in male and female weevils. Males were attracted by α-copaene, α-pinene, β-caryophyllene and linalool, while females by α-copaene, α-pinene, β-caryophyllene, linalool, (E)-β-ocimene and (Z)-linalool oxide furanoid. Overall, this study identified compounds used by R. nigerrimus to find alternative hosts. They might be useful for the management of this pest species.

Plant volatile organic compounds (VOCs) play crucial roles in mediating plant-environment interactions, including pest attraction and deterrence, as well as attracting pollinators and deterring herbivores. The Mediterranean fruit fly (medfly) is a significant pest in fruit crops, requiring precise monitoring to optimize control measures. Our study investigates the differences in VOC profiles between identified “hot spot” areas within orchards where medfly populations tend to concentrate, and “cold spots,” where infestations are less frequent. Using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC–MS), we found that hot spots exhibited distinct VOC profiles, particularly an increase in compounds such as (E)-2-hexenal, (Z)-2-hexanol, (E,E)-2,4-hexadienal, and (E)-2-hexenyl acetate, which are known medfly attractants. These findings suggest that variations in orchard VOC emissions may provide a means of identifying regions at higher risk of infestation, thereby allowing for targeted pest management strategies. This study offers insights into VOC-mediated pest attraction and highlights the potential for refining monitoring systems based on spatial chemical variations in orchards.

Antiaphrodisiacs are chemical bouquets physically delivered from male to female individuals upon copulation which discourage further mating and reduce sperm competition by rendering the female less attractive. Since antiaphrodisiacs may not offer an honest signal of female receptivity, in polyandrous species they may undergo faster diversification resulting from sexual conflict. The Heliconiini tribe of butterflies includes a polyandrous (free-mating) and a monandrous (pupal-mating) clade, both known to produce diverse antiaphrodisiac mixtures as part of their abdominal blends. Using multivariate phylogenetic comparative methods, we analyzed the genital blends of 36 Heliconiini species to test the hypothesis that blend diversity results from male-male competition in polyandry. We found no evidence for shifts in blend diversification rate corresponding to changes in mating strategy, implying male-male competition may have a weaker effect on pheromone diversification in this group than previously thought. The genital blends of most species are dominated by one of four highly volatile compounds; (E)-β-ocimene, octen-3-one, sulcatone and 4-hydroxycyclopent-2-en-1-one. Based on the function of (E)-β-ocimene as the behaviourally active antiaphrodisiac in H. melpomene, we propose a similar role in other species for the other volatiles. We test this hypothesis by investigating 4-hydroxycyclopent-2-en-1-one occurrence in Heliconius sara. While we detect no sex-based differences on its presence, we find the compound is undetectable when larvae are not fed their preferred host plant, providing an intriguing potential link between host plant and reproductive cues. This in turn shows that captive-bred samples do not always provide realistic results and this awareness is important for future experiments.

This study investigates the volatile organic compound (VOC) diversity of Anthemis cotula L., an European native species that has adapted to grow as both summer and winter annual in the Kashmir Himalaya, and explores whether differences in VOC profiles between these growth forms could shed light on their potential role in the plant’s invasiveness and prolific spread in the region. This study identifies 167 VOCs, with winter annuals exhibiting significantly greater VOC diversity (143) compared to summer annuals (88), as also confirmed by significantly higher Shannon and Simpson diversity indices in winter annuals (p < 0.0001). Winter annuals produced 79 unique VOCs, while summer annuals had 24, with plants of both growth cycles sharing 64 compounds. Terpenes, particularly sesquiterpenes, and monoterpenes, dominated in both growth cycles, but winter annuals showed higher diversity, including a higher abundance of esters (34 vs. 21). VOC profiles also varied by plant part: flowers were rich in esters, while roots and leaves had more terpenes. Elevation had a moderate impact on VOC composition, with the greatest variability observed at higher elevations (2350 masl). Functional Hill diversity was significantly higher in winter annuals (p < 0.0001), suggesting a broader biosynthetic diversity. Redundancy analysis revealed that VOC distribution in plant parts was influenced by environmental variables, with altitude showing a stronger correlation in roots. Molecular network analysis showed VOC segregation in distinct clusters, highlighting the biosynthetic pathway complexity and intricate relationships between chemical compounds of different organs in both growth forms. These findings provide critical insights into the potential role of VOC diversity in the invasiveness of A. cotula, particularly its winter annuals in the Kashmir Himalayan region with potential implications for its management.

Dung beetles are of great importance in livestock ecosystems. The utilization of macrocyclic lactones to control cattle parasites has a detrimental effect on the community of dung invertebrates. The objective of this study was to evaluate the attraction of Onthophagus hircus to ivermectin-fortified fecal matter (IFM) under laboratory conditions. Dung beetles primarily detect food through olfaction. To assess odor discrimination behavior, a passive hole-board olfactometer (HBO) was designed. The efficacy of the design was tested through the execution of two control experiments, which measured the attraction (both group and individual) of O. hircus to control fecal matter (CFM) or soil (S). The third experiment was conducted to evaluate individual attraction to IFM. The data were analyzed using descriptive statistics and comparative analyses, and the selection rate was estimated. In both the individual and group control experiences, active individuals were significantly attracted to CFM (46% and 74%, respectively) (p < 0.05 in both cases). Attraction percentages in experiment 3 were: 44% for IFM, 38% for CFM, and 19% for S (p < 0.05). Male and female beetles showed a slight tendency to be attracted to IFM but did not display a significant preference between IFM and CFM (p > 0.05). This study confirmed that an HBO design is a valid approach for testing odor discrimination and assessing the attraction of O. hircus to bovine feces. However, this species demonstrated an inability to differentiate between ivermectin-contaminated and untreated faeces.

Ceratitis capitata, known as Mediterranean fruit fly, represents one of the main problems to the agricultural production, due the ability to infest a wide variety of fruits, which makes it one of the most worrying pests globally. The infestation of host fruits by the insect compromises their quality and appearance, causing losses to their commercialization and consumption. In order to minimize this problem, fruit growers have adopted the indiscriminate use of conventional insecticides that raise environmental and public health concerns, in addition to promoting resistance in insects. Alternatively, semiochemicals have been explored as a management tool, attracting males and females into traps or promoting repellency in exposed fruits. In this context, in silico approaches, as Molecular Docking, Molecular Dynamics and the Virtual Screening procedures, offer opportunities to identify new molecular entities as potential ligands to Odorant Binding Proteins (OBP), that are involved in olfactory communication of C. capitata. In this review, we present a collection of data including the chemistry of olfactory communication of C. capitata and some computational tools that can be used in these studies, emphasizing their impact on the behavior of this and other associated insects. We also address theoretical ADME-Tox parameters as initial evaluation criteria to ensure human safety in the environmental applications, as well as the importance of molecular synergism for the effective management of the medfly.

Cadmium (Cd) toxicity and drought stress are cumulatively disruptive to physiological processes in plants. Salicylic acid (SA) has modulatory roles in osmotic balance in plants. Proline, can act as a compatible solute in osmotic adjustment, elevate antioxidative defense system, which improve adversity tolerance in plants. However, how SA regulates proline metabolism under Cd and drought stresses to improve plant tolerance remains largely unknown. To uncover the alleviation mechanism of SA on Salix matsudana Koidz. seedings to Cd and drought stresses, the non-enzymatic/enzymatic antioxidants, proline metabolism, and related enzyme genes were assayed in S. matsudana. This was done under application of Cd (50 µmol·L^− 1) and polyethylene glycol (PEG) (at concentrations of 5% (w/v)) to induce drought stress in 1/4 Hoagland solution with the application of SA (50 µmol·L^− 1). The results showed that Cd and drought stresses triggered over-accumulation of reactive oxygen species (ROS), and significantly inhibited the growth traits of S. matsudana seedings. Additionally, the combined Cd and drought stresses caused inhibition in root length and plant height. However, SA increased proline accumulation by increasing the activities of ornithine aminotransferase (OAT) and inhibiting the activity of proline dehydrogenase (ProDH), thereby promoting the generation of glutathione (GSH) and ascorbic acid (AsA), and the activities of antioxidative enzymes while also reducing oxidative stress and restoring the growth parameters in Cd and drought-treated S. matsudana. Among the non-enzymatic/enzymatic antioxidative systems, GSH plays a key role in the scavenging of ROS. Accordingly, proline has a vital multifunctional role in exogenous SA-induced Cd and drought stress tolerance.

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