Insecticidal and repellent efficacy of the essential oil from Lobularia maritima and trans-3-pentenenitrile against insect pests of stored grains

Exploring the chemical characterization and insecticidal activities of Curcuma angustifolia roxb. leaf essential oils against three major stored product insects

Botanical pesticides are safe and widely used in pest management. Curcuma angustifolia belongs to the family Zingiberaceae and is a rhizomatous medicinal herb. Following rhizome harvesting, leaves are discarded as waste. However, they can be effectively utilized by extracting essential oils, which are potential biopesticides. The aim of the study is to evaluate the efficacy of the leaf essential oil of Curcuma angustifolia as a potential biopesticide against three stored grain pests, Lasioderma serricorne, Tribolium castaneum, and Callasobruchus chinensis, by their contact, fumigant, and repellent activities. The leaves yield 0.39 ± 0.02 % of oil by hydrodistillation. GC-MS/MS characterization identified curzerenone (18.37 %), geranyl-p-cymene (17.32 %), α-elemenone (13.59 %), eucalyptol (7.58 %) as the main constituents. When exposed to different concentrations of C. angustifolia oil, the test insect displayed noticeably high repellency rates. It also showed better contact toxicity at 24 h, LC50 = 0.22 mg/cm2 for cigarette beetle, LC50 = 0.64 mg/cm2 for red flour beetle, LC50 = 0.07 mg/cm2 for pulse beetle) and fumigation toxicities (LC50 = 10.8 mg/L air at 24 h, for cigarette, LC50 = 29.5 mg/L air for red flour beetle, LC50 = 7.9 mg/L air for pulse beetle). Additionally, a phytotoxicity study was done on paddy seeds, and the results showed no effect on seed germination or seedling growth. It was evident from this study that C. angustifolia oil from waste leaves can be utilized as a botanical pesticide to manage the adults of these storage pests.

Insecticidal and repellent activity of native and exotic lemongrass on Maize weevil

Abstract Corn crop, due to its easy adaptation to the most diverse agroecosystems, spreads throughout the different regions of the world, making it one of the most important agricultural crops. In this crop, pest insects stand out for causing losses both in the field and in warehouses. The application of essential oils can be an important technique to be investigated in the management of insects due to its known insecticidal activity and low risk to the environment. The objective of the work was to value the insecticide and repellent effect of essential oils of exotic lemongrass (Cymbopogon citratus) and native lemongrass (Elionurus sp.) for the management of maize weevil (Sitophilus zeamais (Mots., 1855, Coleoptera: Curculionidae)). The chemical analysis of the oils made by CG-MS showed that the chemical composition of the native and exotic lemongrass is similar, however, the exotic species presented a greater number of compounds. The essential oils of native and exotic lemon grass have efficiency on maize weevil mortality, and it is verified that the increase in the applied dose reflects in a reduction in the insect's exposure time for death to occur. The essential oil of both species showed repellent capacity at all times evaluated. Thus, it can be said that both species have the capacity and potential to be used in the management of corn weevil, and can be an alternative for smallhorders farmers and organic production.

Chemical composition and insecticidal activity of essential oils from cultivated and native aromatic plants of Argentina against Carpophilus dimidiatus (Fabricius) (Nitidulidae) and Oryzaephilus mercator (L.) (Silvanidae)

Essential oils from aerial parts of six aromatic plants were analysed by GC-MS. The major compounds identified were γ-terpinene (11.5%), cuminaldehyde (26.6%) and γ-terpinen-7-al (40.6%) in Cuminum cyminum, trans-anethol (95.2%) in Pimpinella anisum, α-pinene (11.6%), limonene (21.0%), β-caryophyllene (22.3%) and α-humulene (16.7%) in Lippia integrifolia, limonene (40.8%) and artemisia ketone (19.3%) in Lippia junelliana, trans-β-ocimene (15.6%), 4-ethyl-4-methyl-1-hexene (24.5%), trans-tagetone (20.5%) and verbenone (27.2%) in Tagetes minuta, 1,8-cineole (17.9%),elixene (10.3%) and spathulenol (13.8%) in Aloysia gratissima. Oils with strong insecticidal activity on Carpophilus dimidiatus and Oryzaephilus mercator were from P. anisum (LC50 = 4 µl/L; LC100 = 10 µl/L) and T. minuta (LC50=10.19-12.57 µl/L; LC100=20 µl/L). Scents of C. cyminum and L. junelliana were strong insecticides on O. mercator (LC50=7.02-7.17 µl/L; LC100=10.00-20.00 µl/L). The insecticidal activity was associated to the whole content of C10 molecules and oxygenated constituents. The P. anisum oil is promising as protective agent of nut products.

Extraction and chemical characterisation of agro-waste from turmeric leaves as a source of bioactive essential oils with insecticidal and antioxidant activities

Turmeric (Curcuma longa L.) is a significant crop that has historically been used worldwide as a medicinal plant, spice, food colouring agent, and a significant ingredient in cosmetic industries. After harvesting rhizomes, leaves are considered waste material. This research study aims to extract and chemically characterise the essential oil from the leaves waste of turmeric with an evaluation of different insecticidal, antioxidant, and phytotoxic activities. Subsequently, the contact toxicity, fumigant toxicity, and repellent activity were evaluated against two key stored grain insect species. The gas chromatography-mass spectrometry (GC-MS) characterisation revealed that α-phellandrene (28.95%), 2-carene (16.51%), eucalyptol (10.54%) and terpinolene (10.24%) were the major chemical constituents. The study's findings on the insecticidal effects of essential oils extracted from turmeric leaves revealed noteworthy repellent, contact (at 24 h, LC50 = 6.51 mg/cm2 for Tribolium castaneum and LC50 = 4.74 mg/cm2 for Rhyzopertha dominica) and fumigant toxicities (at 24 h, LC50 = 2.57 mg/L air for T. castaneum and LC50 = 2.83 mg/L air for R. dominica), against two key stored grain insects. In addition, turmeric leaf essential oil showed notable antioxidant activity (IC50 = 10.04 ± 0.03 µg/mL for DPPH assay; IC50 = 14.12 ± 0.21 µg/mL for ABTS assay. Furthermore, a phytotoxicity study was carried out on stored paddy seeds and no toxic effects were found on germination rate and seedling growth. So, it might be expected that the essential oils extracted from the turmeric leaf waste could be valorised and demonstrate their potential as safe botanical insecticides against stored-product insects, with noble antioxidant properties.

Evaluation of Halophyte Biopotential as an Unused Natural Resource: The Case of Lobularia maritima

Halophytes are plant species widely distributed in saline habitats, such as beaches, postindustrial wastelands, irrigated lands, salt flats, and others. Excessive salt level, known to limit plant growth, is not harmful to halophytes, which have developed a variety of defense mechanisms allowing them to colonize harsh environments. Plants under stress are known to respond with several morpho-anatomical adaptations, but also to enhance the production of secondary metabolites to better cope with difficult conditions. Owing to these adaptations, halophytes are an interesting group of undemanding plants with a high potential for application in the food and pharmaceutical industries. Therefore, this review aims to present the characteristics of halophytes, describe changes in their gene expression, and discuss their synthesized metabolites of pharmacognostic and pharmacological significance. Lobularia maritima is characterized as a widely spread halophyte that has been shown to exhibit various pharmacological properties in vitro and in vivo. It is concluded that halophytes may become important sources of natural products for the treatment of various ailments and for supplementing the human diet with necessary non-nutrients and minerals. However, extensive studies are needed to deepen the knowledge of their biological potential in vivo, so that they can be introduced to the pharmaceutical and food industries.

Application of clove and dill oils as an alternative of salphos for chickpea food seed storage

Mycological investigations of 25 samples of stored chickpea food seeds (Cicer arietinum L.) from grocery stores of Gurgaon and Gorakhpur revealed occurrence of seventeen fungal species belonging to genus viz., Alternaria, Aspergillus, Chaetomium, Colletotrichum, Curvularia, Fusarium, Penicillium, Rhizopus, Rhizoctonia, and Sclerotium. In these Aspergillus flavus, A. niger, Fusarium oxysporum had dominance in terms of per cent occurrence. Only one species of Bruchid (Callosobruchus chinensis L.) occurred in all the 25 samples. The biodeterioration of seeds inoculated with fungi: A. flavus, A. niger, F. oxysporum and the insect-C. chinensis, revealed their role in seed deterioration. For chickpea food seed protection essential oils were extracted from edible commodity(clove(Lavang and dill(sowa) leaf). Clove(Lavang) oil registered highest antifungal activity inhibiting (100%) mycelial growth of fungi, viz. species Aspergillus flavus, A. niger, Fusarium oxysporum at 300 ppm but was fungicidal at 400 ppm. Dill (Sowa) oil showed complete inhibition at 400 ppm and was fungicidal at 500 ppm. While mixture of both the oils (clove and dill) showed complete inhibition (100%) and fungicidal action at 400 ppm against the dominant fungi. The oils showed 100% insect repellent activity and were found fungicidal at 0.02 ml dose and also insecticidal. The mixture of oils was cidal at 0.02 ml dose. The mixture of oils showed a broad antifungal spectrum at 500 ppm while only 70-93% inhibitory activity at 300 ppm. The oils' mixture's activity was not affected by temp, storage and autoclaving up to 150 days. Oils physico-chemical properties were studied. GC-MS analysis of clove(Lavang) oil depicted major components: 75.63%eugenol while dill(sowa) leaf oil had 25.14% apiole. Formulation of Mixture of oils was more effective showing complete seed protection i.e.no growth of fungi and insects upto 150 days storage than salphos (150 days). While salphos controlled only maximum three fungi (A. terreus, C. dematium, F. moniliforme). The formulated oils mixture did not have any adverse effect on the chickpea seeds and increased their shelf life.