Fumigant Toxicity Of Essential Oils Research Articles

Efficacy of fumigant compounds from essential oil of feverfew (Chrysanthemum parthenium L.) against maize weevil (Sitophilus zeamais Mots.): Fumigant toxicity test and in-silico study

Post-harvest insects are among the significant problems in the agricultural sector. The most accessible tools available for managing post-harvest arthropod-pests are fumigants because of the convenience of their applications and fast action in disinfecting. This study aimed to examine the fumigant toxicity of essential oil (EO) against maize weevil and identify the specific fumigants among the major components. The EO was extracted from aerial part of Chrysanthemum parthenium L. using Clevenger apparatus and was tested for fumigant toxicity. GC-MS was used to determine the chemical composition of EO. The major components were identified and screened virtually using Auto dock vina 1.2. in PyRx 0.8 platform. Dm AChE PDB ID: 6XYY was used as a target for molecular docking and malathion and pirimiphusmethyl were used as a reference for comparison. From the results of binding affinities, most of the major EO components showed better fumigant activity than the reference fumigants. More specifically 1,6-dioxaspiro[4,4]non-ene, b-farensen, bornyl-tiglate, g-terpinene, p-cymene, bornyl-acetate, bornyl-isovalerate, terpinen-4-ol, trans-chrysanthenyl-acetate and a-phellandrene were found to be effective fumigants against maize weevil. The above findings suggest that the EO of the aerial part of C. parthenium can be a potential candidate for the development of novel natural fumigants for stored products.
 KEY WORDS: Essential oil, Fumigants, Insecticides, Binding affinity, Maize weevil
 Bull. Chem. Soc. Ethiop. 2024, 38(2), 457-472. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i2.13

Fumigant Toxicity of Essential Oils against Frankliniella occidentalis and F. insularis (Thysanoptera: Thripidae) as Affected by Polymer Release and Adjuvants

Simple SummaryFrankliniella occidentalis is among the most economically significant pests of greenhouse crops. In contrast, F. insularis is a relatively minor pest with a narrower distribution and host range. We conducted a series of fumigation assays to assess the vulnerability of both species to fumigation with essential oils released from hydrogels. These hydrogels contained either (R)-linalool, (S)-linalool, racemic linalool, or a binary mixture of (R)-linalool with one of twelve other essential oils. Solanum lycopersicum seedlings were screened for their sensitivity to the most potent fumigants, as determined from thrips bioassays. The least saturated hydrogels conditioned in essential oils were the most effective, and both species of thrips were more sensitive to (R)-linalool than to (S)-linalool. Frankliniella occidentalis was significantly more resistant to all treatments than F. insularis. Treatment of S. lycopersicum with the same concentrations of oils required to control thrips resulted in reduced root and hypocotyl lengths, most severely in seedlings exposed via foliar sprays than as fumigants. While our study demonstrates that essential oils are a promising alternative to conventional insecticides for thrips control, the resistance demonstrated by F. occidentalis underlines the need for judicious use of essential oils as part of broader pest control programs.Frankliniella occidentalis is among the most economically significant pests of greenhouse crops, whose resistance to conventional insecticides has created demand for biopesticides such as essential oils. We assessed the fumigant toxicity of linalool against F. occidentalis, F. insularis, and Solanum lycopersicum. Thrips were fumigated with polyacrylamide hydrogels containing either (R)-linalool, (S)-linalool, racemic linalool, or a binary mixture of (R)-linalool with one of twelve adjuvants (i.e., peppermint, cedarwood, neem, clove, coconut, jojoba, soybean, olive, α-terpineol, 1,8-cineole, trans-anethole, or (R)-pulegone). Solanum lycopersicum seedlings were exposed to (R)-linalool or a mixture of (R)-linalool and peppermint oil via conditioned hydrogels or foliar spray. For F. insularis, (R)-linalool was more toxic than (S)-linalool, with LC50 values of 11.7 mg/L air and 16.7 mg/L air, respectively. Similarly for F. occidentalis, (R)-linalool was more toxic than (S)-linalool, with LC50 values of 29.0 mg/L air and 34.9 mg/L air, respectively. Peppermint oil and α-terpineol were the only synergists, while the other adjuvants exhibited varying degrees of antagonism. All seedling treatments demonstrated phytotoxicity, but symptoms were most severe for foliar sprays and mixtures containing peppermint oil. While hydrogels conditioned in linalool may be a favorable substitute to conventional insecticides, the cross-resistance demonstrated herein indicates that expectations should be metered.

Chemical composition and fumigant toxicity of essential oils from ten aromatic plants growing in Egypt against different stages of confused flour beetle, Tribolium confusum Jacquelin du Val

Chemical composition and fumigant toxicity of essential oils from ten aromatic plants growing in Egypt against different stages of confused flour beetle, Tribolium confusum Jacquelin du Val

Fumigant toxicity of essential oils from three lamiaceous plants and methyl iodide against Phthorimaea operculella (zeller) (Lep.: Gelechiidae)

The potato tuberworm, Phthorimaea operculella (Zeller), is a major pest that courses economic losses of potato Solanum tuberosum L. in both the field and the stores. In this research, the fumigant toxicity of essential oils of three Lamiaceous plants including Thymus caucasicus L., Rosmarinus officinalis L. and Satureja hortensis L. and methyl iodide (a chemical fumigant) were evaluated on P. operculella and on its demographic parameters under the laboratory conditions. Essential oils were extracted through hydro-distillation method using a Clevenger-type apparatus. The gas chromatography-mass spectroscopy (GC-MS) analysis indicated that thymol (29.76 %) in T. caucasicus, carvacrol (36.67 %) in S. hortensis and 1, 8-cineole (26.94 %) in R. officinalis essential oils were the major secondary constituents. The 50 % Lethal Concentration (LC50) values for T. caucasicus, R. officinalis, and S. hortensis essential oils as well as methyl iodide towards P. operculella eggs were 5.99, 4.58, 3.55 and 0.29 µL L− 1 air, respectively. On the other hand, methyl iodide showed the highest acute toxicity on the egg stage of P. operculella compared to the essential oils. The 30 % Lethal Concentration (LC30) values of T. caucasicus, R. officinalis, and S. hortensis essential oils and methyl iodide (4.12, 3.53, 1.96, and 0.23 µL L− 1 air, respectively) were affected the life history and demographical parameters of P. operculella. The longest development time was observed on methyl iodide and the shortest was on T. caucasicus and S. hortensis essential oils. The intrinsic rate of natural increase (rm) values obtained in the control group and treated insects were: 0.19, 0.16, 0.14, 0.13, and 0.01 female progenies per female per day for T. caucasicus, S. hortensis, R. officinalis essential oils and methyl iodide, respectively. These results suggested that methyl iodide was significantly more toxic to the P. operculella compared to the essential oils of all the three mentioned plants. Meanwhile, it was concluded that the application of these plant essential oils can be useful as an alternative method for potato tuberworm control in storage facilities.

Chemical Composition and Fumigant Activities of Essential Oils from Piper hancei Maxim against Tribolium castaneum (Herbst).

The present study aimed to analyze the chemical composition and fumigant toxicity of essential oils (EOs) isolated by hydrodistillation from Piper hancei Maxim. EOs extracted from the dry stems and leaves of P. hancei were analyzed by gas chromatography-mass spectrometry (GC-MS). The main compositions of the EOs were humulene (13.624 %), caryophyllene (13.319 %), nerolidol (12.507 %), naphthalene (8.525 %), ledol (6.694 %), caryophyllene oxide (6.404 %), and junenol (6.350 %). The fumigant toxicity of the EOs was tested in 7-14 day old adults of Tribolium castaneum. The LC50 of EOs and individual main compositions were calculated according to the mortality of insects at concentrations of 0, 16, 32, 64, 128, and 256 (μL/L air). The results showed that the EOs (LC50=322.52 (48 h) and 145.82 (72 h) (μL/L air)), caryophyllene (LC50=37.95 (48 h) and 26.53 (72 h) (μL/L air)), junenol (LC50=38.32 (48 h) and 20.33 (72 h) (μL/L air)), caryophyllene oxide (LC50=97.72 (48 h) and 65.22 (72 h) (μL/L air)), and humulene (LC50=104.50 (48 h) and 73.66 (72 h) (μL/L air)) have obvious fumigant activities against T. castaneum adults. The chemical composition of EOs from P. hancei was reported for the first time. The results indicated that the EOs of P. hancei had the potential to be developed as a natural insecticide for the control of T. castaneum adults.

Evaluation of the Toxicity of Satureja intermedia C. A. Mey Essential Oil to Storage and Greenhouse Insect Pests and a Predator Ladybird.

The use of chemical insecticides has had several side-effects, such as environmental contamination, foodborne residues, and human health threats. The utilization of plant-derived essential oils as efficient bio-rational agents has been acknowledged in pest management strategies. In the present study, the fumigant toxicity of essential oil isolated from Satureja intermedia was assessed against cosmopolitan stored-product insect pests: Trogoderma granarium Everts (khapra beetle), Rhyzopertha dominica (Fabricius) (lesser grain borer), Tribolium castaneum (Herbst) (red flour beetle), and Oryzaephilus surinamensis (L.) (saw-toothed grain beetle). The essential oil had significant fumigant toxicity against tested insects, which positively depended on essential oil concentrations and the exposure times. Comparative contact toxicity of S. intermedia essential oil was measured against Aphis nerii Boyer de Fonscolombe (oleander aphid) and its predator Coccinella septempunctata L. (seven-spot ladybird). Adult females of A. nerii were more susceptible to the contact toxicity than the C. septempunctata adults. The dominant compounds in the essential oil of S. intermedia were thymol (48.1%), carvacrol (11.8%), p-cymene (8.1%), and γ-terpinene (8.1%). The high fumigant toxicity against four major stored-product insect pests, the significant aphidicidal effect on A. nerii, and relative safety to the general predator C. septempunctata make terpene-rich S. intermedia essential oil a potential candidate for use as a plant-based alternative to the detrimental synthetic insecticides.

Terpene Rich Essential Oil of <I>Dracocephalum kotschyi</I> Boiss as Efficient Alternative to Synthetic Chemicals in Management of <I>Callosobruchus maculatus</I> Fabricius

The application of plant-derived essential oils has been revealed to proficiently insect pest control agents, meaningfully decreasing the side-effects caused by chemical insecticides. In the present study, the toxicity of essential oil isolated from Dracocephalum kotschyi has been assessed against cowpea weevil (Callosobruchus maculatus Fabricius) as one of the most damaging and cosmopolitan insect pest of stored beans. The other objective of current study was to identify the chemical composition of D. kotschyi essential oil as one of the medicinal plants endemic to Iran. Bioassays results revealed sound fumigant toxicity of essential oil, in which a concentration of 16.41 μl/l produced up to 50% insect mortality after 72 h. Increases in concentrations of the essential oil and exposure times augmented the insect susceptibility so that the highest mortality (96.25%) was achieved at a highest tested concentration (44.12 μl/l) after 72 h. A concentration of 44.12 μl/l was enough to achieve the 50% mortality of tested insects within 10.761 h. The 24 h-LC50 value of essential oil was 24.947 μl/l which decreased to 17.794 μl/l after 72 h. Gas chromatography-mass spectrometry (GC-MS) analysis of the essential oil exposed terpenes including geranyl acetate, citral, z-citral, methyl geranate, limonene, α-pinene and α-campholenal were the main components. Based on the results of present study, the terpene rich essential oil of D. kotschyi may be considered as promising alternative to the synthetic chemicals for C. maculatus management. 
 Keywords: Callosobruchus maculatus, chemical profile, essential oil, Dracocephalum kotschyi, toxicity.

Fumigant toxicity of essential oils and their combinations on population buildup of three stored product coleoptera in stored wheat and effect on quality of wheat

Experiments carried out to find the fumigant toxicity of three essential oils and their combinations from Murraya koenigii, Citrus reticulata, Curcuma longa on population buildup of Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum in stored wheat at different days of infestation. The oil of M. koenigii, C. reticulata at 0.2% and M. koenigii+C. reticulata, M. koenigii+C. longa at 0.1% each were found highly effective against S. oryzae fumigated after 5, 10, 15 and 20 days. The oil of M. koenigii and C. reticulata at 0.2% M. koenigii+C. reticulata, M. koenigii+C. longa, C. reticulata+C. longa at 0.1% each and M. koenigii+C. reticulata+C. longa at 0.07% each were found highly effective against R. dominica fumigated after 5, 10, 15 and 20 days. Only M. koenigii at 0.2% was found highly effective against T. castaneum fumigated after 5, 10, 15 and 20 day. The fumigation of grain with M. koenigii at 0.2% completely suppress the infestation and weight loss when it was fumigated after 5, 10, 15 and 20 days while very low infestation and weight loss was observed in grain treated with M. koenigii +C. reticulata at 0.1% each and not affect the organoleptic properties and germination of wheat.

Ocimum tenuiflorum oil, a potential insecticide against rice weevil with anti-acetylcholinesterase activity

Essential oils are complex secondary metabolites, rich in volatiles, possessing a wide range of biological activities. In recent years, its application as bio-pesticide is receiving renewed attention due to its effective and safe application. In the present study, holy basil (Ocimum tenuiflorum) essential oil was tested for its insecticidal activity against Sitophilus orzyae (L.), using direct contact application and fumigation procedures. The GC–MS analysis of the O. tenuiflorum essential oil was also performed to characterize the essential oil. The GC–MS results showed that the major components present in O. tenuiflorum oil were eugenol and caryophyllene constituting about 70.5% of the total essential oil composition. Fumigant toxicity of essential oil and eugenol standard was assessed at different rates (100-1000 μL/L air) in space fumigation study. Toxicity results revealed that fumigant and contact toxicity of the oils was significantly (p < 0.05) influenced by concentration and exposure time. In contact toxicity assay, O. tenuiflorum essential oil showed the LC50 value of 0.376 μL/cm2 and maximum mortality at 0.786 μL/cm2 concentration after 24 h exposure. In fumigant toxicity assay, O. tenuiflorum essential oil and eugenol showed the LC50 value of 963.3 and 1070.6 μL/L, respectively at 6 h exposure. The O. tenuiflorum essential oil and eugenol was also evaluated for acetylcholinesterase activity in-vivo and was found to affect the acetylcholinesterase activity. The O. tenuiflorum essential oil exhibited insecticidal activity via inhibiting acetylcholinesterase activity and thus can be explored for its application as a possible botanical insecticide.

Comparison of antibacterial effects and fumigant toxicity of essential oils extracted from different plants

The chemical composition, antibacterial and insecticidal potential of Anise, Peppermint, Clove, Cinnamon, Pepper, Citronella and Camphor essential oils (EOs) extracted by steam distillation from seven different plant species were investigated. GC–MS analysis revealed that terpenes and phenols were the main components of EOs. The different kinds of EOs exerted appreciable antibacterial action against Gram-positive (B. subtilis and S. aureus) as well as Gram-negative (E. coli and S. typhimurium) bacteria. Among EOs, cinnamon EO exhibited the highest antibacterial effect for all the bacterial strains with the lowest MIC ranging from 0.125 to 0.25 mg/mL, the largest inhibition zone and the strongest inhibition of bacterial growth, followed by clove EO. The moderate inhibitory effects were observed for remaining EOs. On the other hand, cinnamon EO, clove EO, and anise EO exhibited significant fumigant toxicity against Sitophilus oryzae at 7.69 μL/L air concentration after 24 and 48 h exposure. Furthermore, the single component analysis showed the LC50 values of 2.90 for eugenol, 5.45 for cinnamaldehyde, and 5.42 μL/L air for estragole extracted from selected EOs (clove, cinnamon, anise), respectively. The results will pave a way for utilization of plant derived EOs as natural food preservatives to counteract food spoilage and pest’s managements.

Fumigant toxicity of essential oils against four stored grain insect pests in stored paddy seeds

A laboratory experiment was conducted to find out the fumigant toxicity of essential oils of Murraya koenigii, Citrus reticulata, Curcuma longa, and Pinus. roxburghii against Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum and Sitotroga cerealella for long term protection of paddy seeds in plastic jars. Most of the essential oils either alone or in combinations protect the paddy seeds against test insects up to one year at different concentrations as compare to untreated control. The tested essential oils also prevent the weight losses due to insect infestations. The quality of paddy seeds and germination percentage were not affected by these essential oils.

Insecticidal activity of essential oil from orange peels (Citrus sinensis) against Tribolium confusum, Callosobruchus maculatus and Sitophilus oryzae and its inhibitory effects on acetylcholinesterase and Na+/K+-ATPase activities

This study elucidates the fumigant toxicity and insecticidal mechanism of essential oil from orange peels against T. confusum, C. maculatus and S. oryzae. Essential oil from orange peels was obtained by hydrodistillation. The chemical constituents of the essential oil were identified by gas chromatograph/mass spectrometry (GC-MS). Fumigant toxicity of the essential oil was evaluated against the adults of T. confusum, C. maculatus and S. oryzae. The effect of the essential oil on acetylcholinesterase (AChE) and Na/K-ATPase activities in T. confusum, C. maculatus and S. oryzae homogenates were also determined. The major compounds that were identified in the essential oil include limonene (92.14%), β-myrcene (2.7%), 1,8-cineole (0.33%), α-pinene (0.7%) and γ-Terpinene (0.23%). In the fumigation assay, the essential oil displayed toxic effects against T. confusum, C. maculatus and S. oryzae. Percentage mortality of the insects increased with increase in concentration of the essential oil and exposure time while LC50 reduced with increase in period of exposure. Biochemical studies showed that the essential oil exhibited inhibitory effects on acetylcholinesterase (AChE) and Na+/K+-ATPase activities. This study indicates that essential oil from orange peels could be effective in the biocontrol of T. confusum, C. maculatus and S. oryzae and this may be associated to its inhibitory effects on acetylcholinesterase and Na+/K+-ATPase activity.

Fumigant toxicity of essential oils against four major storage insect pests

As laboratory experiments were carried out to find the fumigant toxicity of 17 essential oils extracted from locally available plants against four storage insect pests, Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum and Callosobruchus Chinensis in wheat and gram. The essential oils from Allium sativum, Artemisia annua, Callistemon citrinus, Chenopodium botrys, Cinnamomum zylanicum, Citrus reticulata, Cuminum cyminum, Foeniculum vulgare, Murraya koenigii, Pinus roxburghii, and Piper nigram were found highly effective against all test insects at 0.2 and 0.4%. The essential oil of Lantana camera, Cinnamomum tamala and Curcuma longa were found highly effective against R. dominica, T. castaneum and C. chinensis at 0.4% concentration.

Fumigant toxicities of essential oils and two monoterpenes against potato tuber moth (Phthorimaea operculellaZeller)

SummaryIntroduction:The potato tuber moth (PTM) is the major economic pest of potato. Different approaches were tried to prevent and control this pest including natural pesticides and synthetic fumigants.Objectives: This study was conducted to evaluate the insecticidal activity of the essential oils of thyme and myrtle. In addition to evaluating the insecticidal activity of carvacrol and eucalyptol against the different life stages of potato tuber moth using a fumigation bioassays.Methods:Thyme and myrtle oils were extracted from wildThymus syriacusBoiss. and wildMyrtus communisL. by hydrodistillation. Fumigation experiments were conducted on potato tuber moth of different stages of development (eggs, larvae, pupae, and adults), using standard methods. The potato tuber moth was treated for different periods using different concentrations of the essential oils. One-way analysis of variance (ANOVA) was applied on the mortality percentages data to estimate the significance of differences between treatments atp&lt;0.05. Probit analysis was used to estimate the LC50, LC90and LT50.Results:Adult stage was the most sensitive to essential oils vapours with LC50value of 0.5μl/l air. Whereas, pupal stages were the most tolerant. The essential oil of thyme possessed the strongest fumigant toxicity against eggs with a LC50value of 6.1μl/l air. The two monoterpens showed varied fumigant toxicity against adult stage. Carvacrol achieved 100% mortality at 0.125μl/l air after 6 h, and 0.025μl/l air after 48h exposure with LT50period of 0.5 h.Conclusion:The present work demonstrated thatT. syriacusessential oil is a promising natural fumigant against the different developmental stages of PTM.

Fumigant toxicity and persistence of essential oils from asafetida, geranium, and walnut on adults of Rhyzopertha dominica (Col.: Bostrichidae)

Fumigant toxicity and persistence of asafetida, geranium, and walnut essential oils were investigated against adults of Rhyzopertha dominica (F.). The experiments were conducted at 28 ± 2 °C, 65 ± 5% RH in continuous darkness. Fumigant toxicity of the essential oils was higher in the empty glass vials than when wheat was treated with the oils. Asafetida oil was more toxic than the two other tested plant species. The essential oil of asafetida was persisted 7 days with 65.71 h half-life time; while the half-life time of geranium and walnut essential oils was 43.39 and 49.37 h, respectively. The present study suggests that asafetida oil may be potential use as stored products protectant.

Fumigant Toxicity of Essential Oil from Lantana camara Against Almond Moth, Cadra cautella (Walker)

Lantana camara is a common weed species in tropics and sub tropics and coastal locations of Asia. The fumigant toxicity of essential oil extracted from leaves of plant was tested against almond moth, Cadra cautella (Walker) (Lepidoptera, Phycitidae). Concentrations of essential oil relative to the wheat grains were 5, 10, 25, 50, 100 and 200 μl/l used against early eggs (0–24 hrs.), late eggs (2–3 days), early larvae (5–7 days), mid larvae (10–12days), late larvae (18–20 days) and early adult (0–24 hrs.) and late adults (2–3 days) stage of C. cautella. The different concentrations of essential oil were applied to Whatman No. 1 with 2.5 cm in diameter filter paper and then pasted on the inner surface of the lid with adhesive tape in the bottom of fumigation flask ten eggs, larvae and adults of different ages with 20 wheat seeds were kept before keeping the treated filter paper, the lid was closed and sealed to create airtight condition in the chamber. The concentrations of essential oil were tested against different stages of test insect and one control with insect and wheat grain but without essential oil was maintained. The experiment was repeated thrice and observation was made at 6, 12, 24 and 48 hrs. of exposure period. Early eggs showed lower LC50 value of 48.56 μl/L compared to 77.75 μl/L with late eggs. The larval LC50 values ranged between 29–39 μl/L. Susceptibility of adult stage was also increased and the LC50 values being 15.23 and 11.21 μl/L for early and late adult stages, respectively.

Contact and fumigant toxicity of Foeniculum vulgare and Citrus limon essential oils against Tetranychus turkestani and its predator Orius albidipennis

Tetranychus turkestani is one of the most important pests of greenhouse plants in the southern provinces of Iran. Several benefits of using essential oils over chemical pesticides make them appropriate for IPM programs. Contact and fumigant toxicity of the essential oils of Foeniculum vulgare and Citrus limon against the spider mite and its predator, Orius albidipennis were investigated under laboratory conditions. Contact toxicity experiments were conducted at six concentrations, (0, 50, 100, 300, 800 and 2000 ppm) of each essential oil on the mature and immature life stages of the pest, and mortalities were recorded 72 h after exposure. In fumigant toxicity trials, LC50 values of the essential oils were determined on different developmental stages of T. turkestani and O. albidipennis. At 800 and 2000 ppm, both essential oils had high contact toxicity on the eggs, 2nd instar nymphs and adults of T. turkestani, while the same concentrations caused less mortality on O. albidipennis. No significant phytotoxicity of the essential oils was observed. The mortality rates of T. turkestani and O. albidipennis increased as concentration was increased. Also, the 2nd instar nymph of T. turkestani was more sensitive to contact application of the essential oils than other developmental stages. In the fumigant toxicity bioassay, LC50 values of the essential oil derived from F. vulgare on the egg, 2nd instar nymph and adult of T. turkestani were 16.08, 7.98 and 14.06, and the values for C. limon essential oil were 11.6, 9.86 and 11.52 μl × l-1air, respectively. The highest fumigant toxicity was observed against the 2nd instar nymphs of the mite. Fumigant toxicity of the essential oils was lower against O. albidipennis than against T. turkestani. This data suggests that the essential oils of these plants have the potential of being employed in the IPM programs of T. turkestani in greenhouse crops, especially cucumber.

Chemical composition and fumigant toxicity of essential oil from Thymus daenensis against two stored product pests

Chemical composition and fumigant toxicity of essential oil from Thymus daenensis against two stored product pests

Comparative efficacy of eighteen essential Oil againstRhyzopertha dominica(F.)

Plants are known to be a potential source of chemicals affecting feeding, breeding and survival of insects. Present study was conducted to study the fumigant toxicity of essential oils against major insect pest of stored grain Rhizopertha dominica. The bio-efficacy of essential oils extracted from eighteen plants, namely, Aegle marmelos, Cinnamomum camphora, Citrus sp., Eucalyptus globules, Psidium guajava, Thuja orientalis, Cymbopogon flexuosus, Bidens pilosa, Ageratum conyzoides, Saraca asoca, Cannabis sativa, Murraya koenigii, Tagetes erecta, Citrus limetta, Artemisia annua, Callistemon citrinus, Ocimum gratissimum and Citrus limon was studied against R. domanica at 0.2, 0.1, 0.05, 0.025, and 0.012% concentration (v/w). The study revealed that most of the essential oils inhibited the development of the test insect. However, the level of inhibition was highly correlated with the dose at which oils were used for treatment. Among eighteen essential oils, A. marmelos, C. camphora E. globulus and T. orientalis were most effective against R. dominica because no insect developed from the grain treated with it even at lower concentration of 0.05%. All the essential oils were found highly effective at 0.2 and 0.1% concentration except A. conyzoides, S. asoca, C. sativa, O. gratissimum and Citrus sp, which permitted adult emergence during test. None of the oil was found highly effective against R. domanica at 0.025 and 0.012% concentration. The essential oil of E. globulus and T. orientalis were found moderately effective at 0.025% concentrations at which they caused 83.92 and 87.17% inhibition, respectively. Rests of the treatments were found less effective against R. dominica due to less than 70% inhibition of progeny production

Essential oil of Tagetes filifolia against the flour beetle Tribolium castaneum and its relation to acetylcholinesterase activity and lipid peroxidation

The development of natural insecticides would help to decrease the negative impact of synthetic insecticides. Fumigant toxicity of essential oil of Tagetes filifolia Lag (Asterales: Asteraceae) and its major compounds were evaluated against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae). The essential oils were analyzed by gas chromatography–mass spectrometry. The essential oil and (E)-anethole were the most toxic at 24 h against adult insects (CL50= 2.4 y 2.6 µL/mL water, respectively). Changes in the products of lipid peroxidation were evidenced by an increase in malondialdehyde content. Acetylcholinesterase activity in vitro, of T. castaneum adults, was also reported. (E)-anethole and estragole showed similar acetylcholinesterase inhibition (54 and 63%, respectively at 5 mM). The present study constitutes one of the first contributions to understanding the relationship between the insecticidal action of essential oil and oxidative stress.