The Essential Oil from the Resurrection Plant Myrothamnus moschatus Is Effective against Arthropods of Agricultural and Medical Interest.

This work aimed to evaluate the chemical composition, insecticidal and acaricidal potential of the essential oil (EO) obtained from the resurrection plant Myrothamnus moschatus (Baill.) Baill. (Myrothamnaceae) from Madagascar. The EO bioactivity was evaluated against selected arthropod pests and vectors of agricultural and public health relevance. The most abundant volatile compounds were trans-pinocarveol (37.7 ± 4.2%) and pinocarvone (20.8 ± 3.1%), similar to the EO of the chemotype collected from the same region. Lethal concentrations (LC50) or doses (LD50) from acute toxicity tests were estimated for Musca domestica (L.) adults at 22.7 µg adult-1, for Spodoptera littoralis (Boisduval) larvae at 35.6 µg larva-1, for Culex quinquefasciatus (Say) at 43.6 µg mL-1, for adults of Metopolophium dirhodum (Walker) at 2.4 mL L-1, and for adults of Tetranychus urticae (Koch) at 1.2 mL L-1. The good insecticidal and acaricidal activities determined in this work may open a new perspective on the use of this plant as a source of botanical insecticide ingredients. The exploitation of this species could also be important for the African economy, helping local farmers cultivating this plant.

Developing a Hazomalania voyronii Essential Oil Nanoemulsion for the Eco-Friendly Management of Tribolium confusum, Tribolium castaneum and Tenebrio molitor Larvae and Adults on Stored Wheat.

Most insecticides commonly used in storage facilities are synthetic, an issue that generates concerns about food safety and public health. Therefore, the development of eco-friendly pest management tools is urgently needed. In the present study, a 6% (w/w) Hazomalania voyronii essential oil-based nanoemulsion (HvNE) was developed and evaluated for managing Tribolium confusum, T. castaneum, and Tenebrio molitor, as an eco-friendly wheat protectant. Larval and adult mortality was evaluated after 4, 8, and 16 h, and 1, 2, 3, 4, 5, 6, and 7 days, testing two HvNE concentrations (500 ppm and 1000 ppm). T. confusum and T. castaneum adults and T. molitor larvae were tolerant to both concentrations of the HvNE, reaching 13.0%, 18.7%, and 10.3% mortality, respectively, at 1000 ppm after 7 days of exposure. However, testing HvNE at 1000 ppm, the mortality of T. confusum and T. castaneum larvae and T. molitor adults 7 days post-exposure reached 92.1%, 97.4%, and 100.0%, respectively. Overall, the HvNE can be considered as an effective adulticide or larvicide, depending on the target species. Our results highlight the potential of H. voyronii essential oil for developing green nanoinsecticides to be used in real-world conditions against key stored-product pests.

Vepris macrophylla (Baker) I. Verd Essential Oil: An Antifungal Agent against Phytopathogenic Fungi.

Rutaceae are widely used in ethnomedicine to treat infectious diseases in humans and plants. In this study, the antifungal activity of the Vepris macrophylla leaf essential oil (VEO) and its main components, citral and citronellol, was evaluated against six phytopathogenic fungi. In addition, the possible action of VEO on the synthesis of mycotoxins was evaluated as well. To determine the antifungal activity of VEO we used the agar dilution method and VEO showed inhibitory activity against all the tested fungi. In particular, VEO resulted to be fungicidal against Phytophthora cryptogea and Fusarium avenaceum. For all other fungi VEO exhibited fungistatic activity and the weakest effect was observed on Alternaria solani. Citral was very effective against P. cryptogea, F. avenaceum, F. poae and F. graminearum. On the other hand, citronellol showed good activity towards P. cryptogea and F. avenaceum and weaker activity towards F. poae and F. graminearum. It can be concluded that VEO can be considered a promising antifungal agent, especially against P. cryptogea and F. avenaceum, suggesting a possible use in the formulation of new selective and natural fungicides.

Chemical composition and insecticidal activity of the essential oil from Helichrysum faradifani endemic to Madagascar.

Helichrysum faradifani (Asteraceae) is a perennial shrub growing in rocky and sandy places of Madagascar. The plant is used in the Malagasy traditional medicine as a wound-healing agent, disinfectant and for the treatment of syphilis, diarrhea, cough and headache. In the present work, we analysed the chemical composition of the essential oil distilled from the aerial parts of H. faradifani by GC-MS and evaluated its insecticidal activity against 2nd, 3rd and 4th instar larvae of the lymphatic filariasis vector Culex quinquefasciatus by acute toxicity assays. The most sensitive were 2nd instar (LC50 = 85.7 µL L-1) larvae. For the 3rd and 4th instar larvae, the estimated LC50 were 156.8 and 134.1 µL L-1, respectively. Monoterpene hydrocarbons (51.6%) were the major fraction of the essential oil, with the bicyclic α-fenchene (35.6%) as the predominant component. Sesquiterpene hydrocarbons (34.0%) were the second major group characterising the oil, with γ-curcumene (17.7%) as the most abundant component.

Effect of the Leaf Essential Oil from Cinnamosma madagascariensis Danguy on Pentylenetetrazol-induced Seizure in Rats.

In the Malagasy traditional practices, the smoke from burning leaves of Cinnamosma madagascariensis Danguy is inhaled to treat brain disorders such as dementia, epilepsy, and headache. In the present work, we have evaluated the in vivo anticonvulsant effects of the essential oil from leaves of C. madagascariensis (CMEO). CMEO was isolated by steam distillation. The anticonvulsant activity of CMEO (0.4 and 0.8 ml/kg bw) administered subcutaneously was evaluated on pentylenetetrazol (PTZ)-induced seizures in Wistar rats; diazepam was used as positive control. Linalool, limonene, and myrcene were the major CMEO constituents. At the dose of 0.8 ml/kg, CMEO completely arrested the PTZ-induced convulsions with moderate sedative effects. The traditional anticonvulsant use of C. madagascariensis was confirmed allowing us to candidate molecules from CMEO as potential drugs to treat convulsions associated with strong agitation.

Chemical composition of the essential oil of Kaliphora madagascariensis Hook. f.

Kaliphora madagascariensis is an evergreen shrub or small tree endemic to Madagascar where it is traditionally used for the treatment of persistent cephalalgia by a strong inhalation of its odour. In this work, we analysed for the first time the essential oil obtained from leaves by Gas Chromatography-Mass Spectrometry. The chemical composition was dominated by oxygenated sesquiterpenes (68.1%), with caryophyllene oxide (14.7%) and ß-eudesmol (10.7%) as the most abundant constituents. These compounds are endowed with documented healthy effects such as analgesic, anti-inflammatory, neuritogenic, antiepileptic and hypotensive, and its abundance might explain the traditional use of the plant in Madagascar.