Volatile chemical composition of Piper sancti-felicis Trel essential oil and its biocidal action against Tribolium castaneum (Herbst)

This research assessed the fumigant activity of the essential oil from Piper sancti-felicis Trel and five of its components on the Tribolium castaneum (Herbst) biological model. Hydrodistillation was used for extraction of the essential oil, with separation and identification of the compounds through gas chromatography coupled to mass spectrometry (GC-MS). The fumigant was evaluated through gas dispersion on the T. castaneum. The majority compounds found in the EO were b-nerolidol (15.4%), 3-carene (14.9%), p-cymene (9.1%), spathulenol (8.2%), a-cubebene (6.2%) and calamenene (5.2%). Piper sancti-felicis displayed fumigant activity with a LC50 = 108.5 μg L-1 air, and other individual monoterpenes tested such as α-terpinolene (LC50 = 110.1 μg L-1 air), p-cymene (LC50 = 120.3 μg L-1 air), 3-carene (LC50 = 130.6 μg L-1 air), (R) -limonene (CL50 = 189.6 μg L-1 air), and a-pinene (LC50 = 213.1 μg L-1 air), were significantly less toxic than methyl pyrimiphos used as a positive control, CL50 = 87.4 μg L-1 air. The essential oil of P. sancti-felicis can be considered as a natural source of biocides

Volatile chemical composition of Colombian Piper gorgonillense Trel. & Yunck. essential oil and its repellent and fumigant activity against Tribolium castaneum Herbst

Essential oils (EOs) are mixtures of volatile organic compounds, mostly terpenes, from the secondary metabolism of plants. These oils exert various activities on insects that damage crops and cause losses worldwide for the economy and agriculture. Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is one of the main pests causing the loss of a large amount of stored food. The objective of this study was to evaluate the volatile chemical composition of the essential oil from Piper gorgonillense Trel. & Yunck. and its repellent and fumigant activity on T. castaneum. The volatile composition was determined with gas chromatography coupled to mass spectrometry. The majority compounds found in the EO were b-caryophyllene (28.7%), a-copaene (13.5%), and d-cadinene (7.3%). The repellency percentages obtained were 78 and 90% at a concentration of 1% with exposure times of 48 and 72 hours, respectively. The fumigant activity refers to the insecticidal action that an essential oil vapor can have without coming into direct contact with insects; this was 100% at a concentration of EO 350 µg mL-1. The results showed that the P. gorgonillense EO had repellent and insecticidal properties for the biological control of T. castaneum.

Toxicity and Synergistic Effect of Elsholtzia ciliata Essential Oil and Its Main Components against the Adult and Larval Stages of Tribolium castaneum

Investigations have indicated that storage pests pose a great threat to global food security by damaging food crops and other food products derived from plants. Essential oils are proven to have significant effects on a large number of stored grain insects. This study evaluated the contact toxicity and fumigant activity of the essential oil extract from the aerial parts of Elsholtzia ciliata and its two major biochemical components against adults and larvae of the food storage pest beetle Tribolium castaneum. Gas chromatography–mass spectrometry analysis revealed 16 different components derived from the essential oil of E. ciliata, which included carvone (31.63%), limonene (22.05%), and α-caryophyllene (15.47%). Contact toxicity assay showed that the essential oil extract exhibited a microgram-level of killing activity against T. castaneum adults (lethal dose 50 (LD50) = 7.79 μg/adult) and larvae (LD50 = 24.87 μg/larva). Fumigant toxicity assay showed LD50 of 11.61 mg/L air for adults and 8.73 mg/L air for larvae. Carvone and limonene also exhibited various levels of bioactivity. A binary mixture (2:6) of carvone and limonene displayed obvious contact toxicity against T. castaneum adults (LD50 = 10.84 μg/adult) and larvae (LD50 = 30.62 μg/larva). Furthermore, carvone and limonene exhibited synergistic fumigant activity against T. castaneum larvae at a 1:7 ratio. Altogether, our results suggest that E. ciliata essential oil and its two monomers have a potential application value to eliminate T. castaneum.

Identification and Characterization of Nnematicidal Volatile Organic Compounds from Deep-Sea Virgibacillus dokdonensis MCCC 1A00493

Root-knot nematode diseases cause severe yield and economic losses each year in global agricultural production. Virgibacillus dokdonensis MCCC 1A00493, a deep-sea bacterium, shows a significant nematicidal activity against Meloidogyne incognita in vitro. However, information about the active substances of V. dokdonensis MCCC 1A00493 is limited. In this study, volatile organic compounds (VOCs) from V. dokdonensis MCCC 1A00493 were isolated and analyzed through solid-phase microextraction and gas chromatography–mass spectrometry. Four VOCs, namely, acetaldehyde, dimethyl disulfide, ethylbenzene, and 2-butanone, were identified, and their nematicidal activities were evaluated. The four VOCs had a variety of active modes on M. incognita juveniles. Acetaldehyde had direct contact killing, fumigation, and attraction activities; dimethyl disulfide had direct contact killing and attraction activities; ethylbenzene had an attraction activity; and 2-butanone had a repellent activity. Only acetaldehyde had a fumigant activity to inhibit egg hatching. Combining this fumigant activity against eggs and juveniles could be an effective strategy to control the different developmental stages of M. incognita. The combination of direct contact and attraction activities could also establish trapping and killing strategies against root-knot nematodes. Considering all nematicidal modes or strategies, we could use V. dokdonensis MCCC 1A00493 to set up an integrated strategy to control root-knot nematodes.

Volatile chemical composition of essential oil from Bursera graveolens (Kunth) Triana & Planch and their fumigant and repellent activities

The objectives of this work were the study of the volatile chemical composition of essential oils (EO’s) from Bursera graveolens obtained in the locality of Malagana, municipality of Mahates, Bolívar, Colombia, as well as to evaluate their repellent and fumigant properties. EO’s were extracted by hydro-distillation and characterized by gas chromatography-mass spectrometry (GC-MS). The major compounds found in B. graveolens were limonene (42.2%), pulegone (20.9%), carvone (7.5%), caryophyllene (4.1%), and trans-carveol (3.8%). The repellent activity of EO’s was determined by the area preference method, where the EO of B. graveolens presented repellent activity against the Tribolium castaneum weevil at a concentration of 1 at 2% and 4 hours of exposure (88.1 and 88.6% respectively). B. graveolens essential oil was more effective in its fumigant activity with LC50 of 108.2 μg oil mL-1. Also, the fumigant and repellent activities of two individual compounds present in the oil were evaluated, that is, limonene (majority) and caryophyllene. The results indicated that B. graveolens essential oil could be a promising alternative to new natural repellents and biocides.