Andean Plants Essential Oils: A Scented Alternative to Synthetic Insecticides for the Control of Blowflies

Blowflies are vectors of microorganisms and human pathogens, and their maggots cause myiasis in vertebrates and infest and spoil meat and fish products. Essential oils (EOs) from spices were proven to be a safer and more sustainable alternative to synthetic insecticides for the control of blowflies and are suitable for protecting food from such pests. However, some EOs are not acceptable for environmental or topical applications due to their strong, unpleasant odour. In this study, we measured the acute toxicity and the repellence of two EOs extracted from the Andean plants Aloysia citrodora Palau and Bursera graveolens (Kunth) Triana and Planch., both known for their pleasant odour, against the blue blowfly Calliphora vomitoria (L.) (Diptera: Calliphoridae). We also compared their bioactivity with that of the Allium sativum L. EO, which is very effective but bad-smelling. The A. citrodora EO was mainly rich in oxygenated monoterpenes, the most abundant of which were geranial (26.8%) and neral (21.0%). The B. graveolens EO was chiefly composed of monoterpene hydrocarbons, mostly represented by limonene (46.2%). According to the sensory description, the best odour profile was associated with the A. citrodora EO, while the olfactory expression of the EO from B. graveolens was negatively affected by a strong odour of “mouldy lemon”. The behavioural test showed that the A. citrodora EO was more repellent than that of A. sativum and, on the contrary, that the B. graveolens EO was attractive. The toxicity tests showed that the EOs of both Andean plants have a clear toxic effect on the C. vomitoria eggs and adults. In terms of ovicidal activity, there were no significant differences among the effects of the three tested EOs. On the adult flies, the toxicity of the two EOs of the Andean plants was much lower than that of A. sativum (LC50 fumigation = 1.86 μL EO L−1 air; LC50 ingestion = 8.10 μL EO mL−1 gel) both by fumigation (LC50 = 23.66 and 25.30 μL EO L−1 air for A. citrodora and B. graveolens, respectively) and ingestion (LC50 = 36.65 and 44.97 μL EO mL−1 gel for A. citrodora and B. graveolens, respectively), while, by contact, the A. citrodora EO (LD50 = 0.27 μL EO insect−1) was more toxic than the A. sativum EO (LD50 = 0.46 μL EO insect−1).

The flowerpiercers interactions with a community of high Andean plants

Background Flowerpiercers (Diglossa) are traditionally considered as “parasites” of the pollination processes, as they can access the nectar without entering in contact with the reproductive structures of the plants. Nevertheless, the effect of flowerpiercers seems to vary according to their behavior and the flower’s traits. So, in this work, we aimed to explore the floral characteristics that may determine the susceptibility to robbing and pollen transport by flowerpiercers. Also, we identified the potential types of interactions and studied interaction network properties. Methods We collected the information of 16 ornithophilic plants regarding their floral traits and robbing frequency. Also, we captured 4 species of flowerpiercers and evaluated pollen transport (frequency and loads). We tested the correlation between floral traits, robbing frequency, and pollen transportation. Later, we used these variables in a cluster and principal component analyses to identify the potential types of interactions. Finally, we analyzed and compared the structure of the plants-flowerpiercers interaction network. Results Nectar production significantly influenced both nectar robbing and pollen transportation. While the corolla length was only correlated to the robbing susceptibility. Also, we found that particular flowerpiercers species transported higher loads of some plant pollen, which can be related to the differences in behavior and morphometric traits. We proposed the classification of five different types of plant-flowerpiercer interactions, that showed different potential mutualist or antagonist relations based on the affectation of nectar robbing and the service of pollen transportation. The interaction networks consisted of 49 links, with 2.4 links per species, and presented indicators of a medium to high resilience, stability, and resistance (nestedness, connectance, and robustness). Also, the network presented medium to low specialization and substantial niche overlap. Conclusions The ecological role of the flowerpiercers goes beyond its classic assignation as “parasites” as they can actively transport pollen of several Andean plants, affecting its evolutionary history and the stability of the systems.

Effect of the Andean Geography and Climate on the Specialized Metabolism of Its Vegetation: The Subtribe Espeletiinae (Asteraceae) as a Case Example

The Andean mountains are ‘center stage’ to some of the most spectacular examples of plant diversifications, where geographic isolation and past climatic fluctuations have played a major role. However, the influence of Andean geography and climate as drivers of metabolic variation in Andean plants is poorly elucidated. Here, we studied the influence of those factors on the metabolome of the subtribe Espeletiinae (Asteraceae) using liquid chromatography coupled to high-resolution mass spectrometry data of over two hundred samples from multiple locations. Our results demonstrate that metabolic profiles can discriminate Espeletiinae taxa at different geographic scales, revealing inter- and intraspecific metabolic variations: at the country level, segregation between Colombian and Venezuelan taxa was observed; regionally, between páramo massifs; and locally, between páramo complexes. Metabolic differences in Espeletiinae were mainly explained by geographic isolation, although differences in taxonomic genera, temperature, and elevation, were also important. Furthermore, we found that different species inhabiting the same páramo complex showed stronger chemical similarities than the same species at different locations, corroborating that geographic isolation represents the main driver of metabolic change in Espeletiinae. The current study serves as a starting point to fill in the gaps in how Andean geography and climate have shaped the metabolism of its vegetation and reveal the potential of untargeted metabolomics to study the environmental physiology of plants.

Antimicrobial Diterpenes from Azorella Species against Gram-Positive Bacteria

The present study was aimed at evaluating the antibacterial activity of mulinane and azorellane diterpenes isolated from the Andean plants Azorella compacta and A. trifoliolata and semisynthetic derivatives against reference and multidrug-resistant strains. The results revealed that the semisynthetic compound 7-acetoxy-mulin-9,12-diene (5) exhibited antibacterial activity against reference and multidrug-resistant strains of Staphylococcus aureus and moderate antimycobacterial activity against Mycobacterium smegmatis ATCC 14468.