Xylopia ochrantha essential oil against the peanut beetle

Simple SummaryEssential oils (EOs) from plants are promising products for pest management. This paper describes the chemical composition and repellent action of four EOs against Ulomoides dermestoides, a common pest on several stored products. Most abundant chemical components found in the EOs were sabinene, trans-β-caryophyllene, and α-humulene for phellandrene-rich Lippia origanoides; limonene and carvone for carvone-rich Lippia alba; geranial, geraniol, and neral for citral-rich Lippia alba; and α-guaiene, α-bulnesene, and patchoulol for Pogostemon cablin. The repellent bioactivity, carried out utilizing the area preference method, showed that all EOs displayed great repellency with low mortality rates, suggesting these natural mixtures can be used in formulations of repellents against stored grain pests.The essential oils (EOs) from bioactive species can provide an alternative tool for the management of stored grain insects that is less environmentally damaging than synthetic chemicals. The aim of this study was to assess the repellent action and toxicity of EOs obtained from phellandrene-rich Lippia origanoides, carvone-rich Lippia alba, citral-rich L. alba, and Pogostemon cablin aerial parts on adults of Ulomoides dermestoides. These EOs were isolated by hydrodistillation and characterized by gas chromatography coupled to mass spectrometry (GC-MS). The repellency assay was carried out using the area preference method, and the toxicity evaluated utilizing a filter paper contact test. The major components (>10%) of the studied EOs were sabinene (16.9%), trans-β-caryophyllene (18.6%) and α-humulene (10.1%) for phellandrene-rich L. origanoides EO; limonene (40.1%) and carvone (37.7%) for carvone-rich L. alba EO; geranial (24.5%), geraniol (19.0%), and neral (11.9%) for citral-rich L. alba EO; and α-guaiene (13.3%), α-bulnesene (15.7%), and patchoulol (35.3%) for P. cablin EO. All EOs displayed 100% repellency at a concentration of 16 μL/mL, with lower toxicity than that elicited by the commercial repellent DEET. EO concentrations up to 8 µL/mL did not induce any mortality on the beetle. These findings show that the EOs provide active and safe molecules for natural repellent formulations to prevent and control insect infestations of stored products.

Essential oils (EOs) represent valuable alternatives in handling pest insects in stored grains. The main objective of this study was to evaluate the chemical composition as well as the repellent, fumigant, and oviposition inhibition activities of the rosemary (Rosmarinus officinalis) and citronella (Cymbopogon nardus) EOs against Ulomoides dermestoides. Ethyl 3-[acetyl(butyl)amino] propanoate (IR3535), an active ingredient in repellent formulations was used as a positive control. The chemical compositions of the EOs were characterized by GC/MS. The EOs major compounds (>10 %) included 1,8-cineole (24.6 %), α-pinene (17.7 %), camphor (12.4 %), and camphene (11.3 %) for rosemary, whereas for citronella, the most abundant components were citronellal (25.3 %), citronellol (17.9 %) and geraniol (11.6 %). The biological action observed was dependent on the concentration used. Both EOs showed 100 %-repellency at the highest tested concentration (16 μL/mL) with RC50 values lower than 2.6 μL/mL after 4 h-exposure. Contact toxicity results showed that all treatments had mortality rates lower than 40 %, while fumigant action did not exceed 25 %. The exposure of adult insects to sublethal concentrations of the two EOs significantly inhibited oviposition at 2 and 4 μL/mL. These data suggest that citronella and rosemary EOs, employing different toxicity mechanisms, could be useful candidates for formulations utilized in the management and pest control in stored products.

Insecticidal and repellent activities of Cymbopogon citratus (Poaceae) essential oil and its terpenoids (citral and geranyl acetate) against Ulomoides dermestoides

Essential oils (EOs) are widely used as biopesticides and to control bacterial infections. This study describes the ability of six EOs isolated from plants cultivated in Colombia to perform as repellents against Ulomoides dermestoides and as quorum sensing (QS) inhibitors. EOs from Aloysia triphylla, Cymbopogon nardus, Lippia origanoides, Hyptis suaveolens, Swinglea glutinosa and Eucalyptus globulus were repellents classified as Class IV, IV, IV, III, II, and II, respectively, whereas the commercial repellent IR3535 only reached Class II after 2 h exposure. All EOs presented small, but significant inhibitory properties against the QS system in Escherichia coli (pJBA132) at 25 μg/mL after 4 h exposure. These data suggest evaluated EOs from Colombia are sustainable, promising new sources of natural repellents and could be important as anti-quorum sensing molecules.

Purpose: To investigate contact and fumigant toxicity of the essential oil of Bidens frondosa and its isolated constituents against booklice (Liposcelis bostrychophila).Methods: The essential oil of B. frondosa was obtained by hydro-distillation and analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) with HP-5MS column. The active constituents were purified from the oil by bioactivity-guided fractionation. Contact (impregnated filter paper method) and fumigant toxicity (sealed space) of the oil and its isolates were determined.Results: Thirty-two compounds, representing 98.88 % of the total oil, were determined and the major constituents of the essential oil were caryophyllene oxide (20.50 %), borneol (17.66 %), 4-terpineol (17.26 %), and β-cedrene (6.94 %). The essential oil displayed fumigant toxicity against booklice, with a median lethal concentration (LC50) of 507.35 μg/L while the isolated constituents, borneol and 4-terpineol, had LC50 values of 2.20 mg/L and 335.24 μg/L against booklice, respectively. The essential oil also exhibited contact toxicity against L. bostrychophila with an LC50 value of 210.73 μg/cm2. Borneol, caryophyllene oxide, β-cedrene, and 4-terpineol showed acute toxicity against booklice with LC50 of 98.04, 84.62, 458.79 and 211.35 μg/cm2, respectively.Conclusion: The results suggest that the essential oil and its isolates possess potential for cultivation into natural insecticides or fumigants, for control of insects in stored grains.Keywords: Bidens frondosa, Liposcelis bostrychophila, Contact toxicity, Essential oil, Boolice, Stored grains, Natural insecticides, Fumigants

Chemical characterisation, insecticidal and antioxidant activities of essential oils from four Citrus spp. fruit peel waste

Coleoptera poses a threat to quality standards in crop production and storage, where it can cause large production losses as a fundamental organism for the transmission of plant diseases. Several synthetic products have been used for their control, with reported adverse effects on the health of exposed animals and humans. The use of essential oils (EOs) is an excellent alternative for the control of pests in crop production and storage, due to their high rate of safety for people and the environment. In the present study, EOs were obtained from three plant species cultivated in Colombia characterized by GC/MS Elettaria cardamomum, Salvia officinalis and Lippia origanoides (Carvacrol chemotype). These three plant species were evaluated for repellent and fumigant functions against Tribolium castaneum and Ulomoides dermestoides. The main component in E. cardamomum and S. officinalis was 1.8-cineole (23.4 and 30.9 %), whereas in L. origanoides it was carvacrol (32.3 %). EOs depicted concentration-dependent biological effects. L. origanoides exhibited the maximum percentage of mortality and the highest repellent potency with RC50 of 0.220 % for T castaneum, and 0.207 % for U. dermestoides. These results showed that the EOs from E. cardamomum, S. officinalis and L. origanoides are promising species for use in integrated pest management.

The main pathogen underlying citrus variegated chlorosis (CVC), a citrus fruit disease, is Xylella fastidiosa, a Gram‐negative s‐shaped bacterium that blocks water and nutrient circulation. Discovering new pesticides to combat CVC have become a challenge. Research into essential oils (EOs) is crucial because these substances can be potentially useful in pest control. This study aims to determine minimum inhibitory concentrations (MIC), to investigate biofilm inhibition capacities through MBIC50 analysis, and to evaluate synergistic effects with streptomycin of 17 EOs against X. fastidiosa. This study also analyses the chemical profiles of the EOs that provided the best antibacterial activity results. The MIC values of the EOs ranged from 125 to 1,000 µg/ml. Analysis of the MICB50 values of the sandalwood and patchouli EOs revealed biofilm inhibitory activity. No synergistic effects were evident for streptomycin combined with the sandalwood or patchouli EOs: ΣFIC was 1.25 and 1.5, respectively, which denoted indifference. We detected α‐gurjunene (27.6%), patchouli alcohol (21.6%), α‐bulsene (17.3%) and α‐patchoulene (6.3%) as the major patchouli EO constituents. On the basis of our results, the sandalwood and patchouli EOs present antibacterial action and are promising natural sources for the development of new pesticides against X. fastidiosa.

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

In this study, four kinds of chemical substances (2,3,5,6-tetramethylpyrazine, β-ionone, citronellal, and paeonol), three kinds of plant essential oils (tea tree essential oil, lavender essential oil, and myrrh essential oil), and their combinations were selected to explore their synergistic effects on tobacco beetle [Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae)] adults by the behavioral test and laboratory simulation test. Behavioral test results showed that some of the combinations revealed a synergistic effect on tobacco beetle adults, especially the sexual attractant +2,3,5,6-tetramethylpyrazine + β-ionone + citronellal + paeonol (SABCD, one portion of sexual attractant, and 1 mg/L synergistic substances) combination and the food attractant +2,3,5,6-tetramethylpyrazine + paeonol (FAD, 1 ml of food attractant and 1 mg/L synergistic substances) combination showed the best behavioral effect on tobacco beetle adults with average dwell times of 120.97 and 126.74 s, respectively, compared to those of other combinations. Meanwhile, SABCD had the highest selection rate [89.47%, about 1.5 times that of the sexual attractant (S)] on tobacco beetle adults compared with those of other combinations. In addition, laboratory simulation test results showed that the SABCD combination had the highest average selection rate (37.31%, about 2 times that of S) on tobacco beetle adults at 1 mg/L. However, our results showed that there was no significant difference in the indoor simulation results of food attractant synergistic substances. Our results will provide guidance for the development of new pesticides for tobacco beetle adults.

Grain production grows more every year, and stored grain pests have been a challenge for agriculture. The use of pesticides is the main solution to face this challenge; however, improper and extensive management leads to another difficulty: the resistance acquired by some pests, causing their ineffectiveness. Thus, essential oils and other natural products emerge as an alternative to overcome this situation. In this study, several essential oils with insecticidal/repellent properties were reviewed to evaluate the capacity to become an important method for protecting stored grains against the most recurrent pests. This is a literature review that analyzed articles in scientific database platforms, using different combinations of the keywords “Essential oils”, “Insecticides”, “Stored grains”, “Repellents” and “Insects”. Among the essential oils studied, the most outstanding were the essential oils of: Artemisia argyi and Mentha haplocalyx against Lasioderma serricorne; Artemisia rupestris and Ligusticum pteridophyllum against Liposcelis bostrychophila; and Artemisia anethoides, Elshotzia ciliata, and Amomum maximum against Tribolium castaneum. Along with some essential oils, their main components and insecticidal/repellent capacity when isolated were also evaluated. The results were promising, although mechanisms of action have not yet been elucidated. Investing in research for alternative pest control can contribute to sustainable agriculture.

Ulomoides dermestoides are used as a broad-spectrum medical insect in the alternative treatment of various diseases. Preliminary volatilome studies carried out to date have shown, as the main components, methyl-1,4-benzoquinone, ethyl-1,4-benzoquinone, 1-tridecene, 1-pentadecene, and limonene. This work focused on the production of metabolites and their metabolic variations in U. dermestoides under stress conditions to provide additional valuable information to help better understand the broad-spectrum medical uses. To this end, VOCs were characterized by HS-SPME with PEG and CAR/PDMS fibers, and the first reported insect essential oils were obtained. In HS-SMPE, we found 17 terpenes, six quinones, five alkenes, and four aromatic compounds; in the essential oils, 53 terpenes, 54 carboxylic acids and derivatives, three alkynes, 12 alkenes (1-Pentadecene, EOT1: 77.6% and EOT2: 57.9%), 28 alkanes, nine alkyl disulfides, three aromatic compounds, 19 alcohols, three quinones, and 12 aldehydes were identified. Between both study approaches, a total of 171 secondary metabolites were identified with no previous report for U. dermestoides. A considerable number of the identified metabolites showed previous studies of the activity of pharmacological interest. Therefore, considering the wide variety of activities reported for these metabolites, this work allows a broader vision of the therapeutic potential of U. dermestoides in traditional medicine.

Bean weevil and maize weevil can cause considerable damage to stored grains. These insects are mainly controlled with synthetic chemical insecticides, which may bring serious problems to human and environmental health. Therefore, this study aimed to evaluate the efficiency of the essential oil of clove [Syzygium aromaticum (L.) Merrill & Perry (Myrtaceae) (origin: Bahia, season Sep.2014-Feb.2015)] in the control of S. zeamais and A. obtectus under laboratory conditions. The essential oil was extracted through the classic hydrodistillation process and its chemical components were identified via gas chromatography. Oil efficiency was tested at the doses of 35, 17.9, 8.9, 3.6, 1.8, 0.4 and 0.2 μL g-1 (derived from a pilot study) for insect control and the LC50 was determined. The results showed that eugenol was the major compound. The essential oil caused mortality of 100% for both species 48 h after treatment with the concentrations of 17.9 and 35 μL g-1. The LC50 for A. obtectus was 9.45 μL g-1, against 10.15 μL g-1 for S. zeamais. The use of clove essential oil represents a promising alternative to be used under storage conditions for the integrated management of stored grains pests.

Pesticidal potential of some wild plant essential oils against grain pests Tribolium castaneum (Herbst, 1797) and Aspergillus flavus (Link, 1809)

Essential oils (EOs) have gained increasing interest as a low-toxic, eco-friendly alternative to synthetic repellents and insecticides against insect pests. However, they have scarce practical application in the protection of stored grain because of their limited efficacy and their interference with the organoleptic properties of the grain. In this study, we evaluated the olfactory profile of the EOs of Foeniculum vulgare, Pistacia lentiscus, and Ocimum basilicum, and their toxicity against the main stored grain pest Sitophilus granarius. Trained assessors identified O. basilicum and F. vulgare, as more suitable than the P. lentiscus EO for the wheat treatment. In laboratory tests, the most toxic EO was the P. lentiscus (LC50 = 36.36 μL∙kg−1) while, the least toxic, was the F. vulgare one (LC50 = 77.59 μL∙kg−1). The EOs were also tested combined with diatomaceous earths (DEs) showing synergistic effects (co-toxicity coefficient values ranging from 1.36 to 3.35 for O. basilicum and F. vulgare EOs, respectively). Overall, O. basilicum resulted as the best EO for the wheat treatment, considering its insect toxicity and olfactory profile. In real storage conditions, the wheat co-treated with O. basilicum EO and DEs showed a significantly lower mean infestation (1.5 insect kg−1) than the non-treated wheat (7.0 insect kg−1).