Water-distilled essential oil from the dried bulbs of Allium chinense (Liliaceae) was analyzed by gas chromatography–mass spectrometry (GC–MS). Eighteen compounds, accounting for 98.4% of the total oil, were identified and the main components of the essential oil of A. chinense were methyl allyl trisulfide (30.7%), dimethyl trisulfide (24.1%), methyl propyl disulfide (12.8%) and dimethyl disulfide (9.6%) followed by methyl allyl disulfide (3.4%) and methyl propyl trisulfide (3.6%). The essential oil exhibited contact toxicity against the booklice ( Liposcelis bostrychophila ) with an LC 50 value of 441.8 μg/cm 2 while the two major constituents, dimethyl trisulfide and methyl propyl disulfide had LC 50 values of 153.0 μg/cm 2 and 738.0 μg/cm 2 against the booklice, respectively. The essential oil of A. chinense possessed strong fumigant toxicity against the booklice with an LC 50 value of 186.5 μg/l while methyl allyl trisulfide (LC 50 = 90.4 μg/l) and dimethyl trisulfide (LC 50 = 114.2 μg/l) exhibited stronger fumigant toxicity than methyl propyl disulfide (LC 50 = 243.4 μg/l) and dimethyl disulfide (LC 50 = 340.8 μg/l) against the booklice. The results indicated that the essential oil and its major constituents have potential for development into natural insecticides or fumigants for control of insects in stored grains.
This study was designed to evaluate the acaricidal effect and the mode of action of lemongrass essential oil (LEO) against Aleuroglyphus ovatus. Contact and fumigant mortality indicated that LEO had higher acaricidal activities at a low concentration, and the acaricidal action of LEO was significantly more effective by contact effects than by fumigant bioassay. Repellent rate against A. ovatus at different concentrations of LEO increased with application time. Observation on the toxic symptoms revealed that almost all mites were in immobilized type (IM type) in 30 min, but the symptom of knock-down type (KD type) appeared later. Cuticles of mites killed by LEO exhibited obvious colour change and deformation. Detoxification enzyme activity assay showed that glutathione S-transferase (GST) activity increased in mites treated by LEO compared to the controls. LEO increased catalase (CAT) activity of A. ovatus but inhibited superoxide dismutase (SOD) after 20 h. LEO also increased nitric oxide synthetase (NOS) and inhibited acetylcholine esterase (AChE) activities. Moreover, LEO acted as a fast-acting neurotoxin on A. ovatus. Our results suggest that LEO has an acaricidal potential and is a promising agent in control of A. ovatus.
Background: The efficacy of essential oil of Chenopodium ambrosioides flowering aerial parts and its three main active ingredients was evaluated against Blattella germanica male adults. Methods: Composition of essential oil was determined by GC-MS. Topical application bioassay was used to evaluate contact toxicity of essential oil and three main components. Fumigant toxicity of essential oil and its main components was measured using a sealed space method. Results: Twenty-two components were identified in the essential oil and the main components were ( Z )-ascaridole (29.7%), isoascaridole (13.0%), ρ-cymene (12.7%) and piperitone (5.0%). The essential oil and ( Z )-ascaridole, isoascaridole and ρ-cymene possessed fumigant toxicity against male German cockroaches with LC 50 values of 4.13, 0.55, 2.07 and 6.92 mg/L air, respectively. Topical application bioassay showed that all the three compounds were toxic to male German cockroaches and ( Z )-ascaridole was the strongest with a LD 50 value of 22.02 μg/adult while the crude oil with a LD 50 value of 67.46 μg/adult. Conclusion: The essential oil from Chinese C. ambrosioides and its three main active ingredients may be explored as natural potential insecticides in the control of cockroaches.
Xin Chao Liu,Yin Ping Li,He Qin Li,Zhi Wei Deng,Ligang Zhou,Zhi Long Liu,Shu Shan Du
The aim of this research was to determine the chemical composition and insecticidal and repellent activity of the essential oil ofArtemisia rupestrisL. aerial parts against the bookliceLiposcelis bostrychophilaBadonnel and isolation of insecticidal and repellent constituents from the essential oil. The essential oil ofA. rupestriswas obtained by hydrodistillation and analyzed by GC-MS. A total of 30 components of the essential oil ofA. rupestriswas identified and the principal compounds in the essential oil were α-terpinyl acetate (37.18%), spathulenol (10.65%), α-terpineol (10.09%), and linalool (7.56%), followed by 4-terpineol (3.92%) and patchoulol (3.05%). Based on bioactivity-guided fractionation, the four active constituents were isolated from the essential oil and identified as α-terpineol, α-terpinyl acetate, 4-terpineol and linalool. The essential oil ofA. rupestrisexhibited contact toxicity againstL. bostrychophilawith LD50value of 414.48 µg/cm2. α-Terpinyl acetate (LD50= 92.59 µg/cm2) exhibited stronger contact toxicity against booklice than α-terpineol (LD50= 140.30 µg/cm2), 4-terpineol (LD50= 211.35 µg/cm2), and linalool (LD50= 393.16 µg/cm2). The essential oil ofA. rupestris(LC50= 6.67 mg/L air) also possessed fumigant toxicity againstL. bostrychophilawhile the four constituents, 4-terpineol, α-terpineol, α-terpinyl acetate and linalool had LC50values of 0.34, 1.12, 1.26 and 1.96 mg/L air, respectively. α-Terpinol and α-terpinyl acetate showed strong repellency againstL. bostrychophila, while linalool and 4-terpinol exhibited weak repellency. The results indicate that the essential oil ofA. rupestrisaerial parts and its constituent compounds have potential for development into natural insecticides or fumigants as well as repellents for control of insects in stored grains.Keywords:Liposcelis bostrychophila;Artemisia rupestris;contact toxicity;fumigant toxicity;repellency;essential oil composition
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