Vapor Phase Toxicity Bioassays Research Articles

Fumigant toxicity of basil oil compounds and related compounds to Thrips palmi and Orius strigicollis.

This study was aimed at assessing the fumigant toxicity to adult Thrips palmi (a serious insect pest) and Orius strigicollis (a beneficial predator insect) of basil (Ocimum basilicum) essential oil compounds and structurally related compounds using vapour-phase toxicity bioassays. Against adult T. palmi, linalool (LD50 0.0055 mg cm(-3) ) was the most toxic fumigant and was 15.2-fold more effective than dichlorvos (0.0837 mg cm(-3) ). Strong fumigant toxicity was also observed in pulegone (0.0095 mg cm(-3) ), (±)-camphor (0.0097 mg cm(-3) ) and 1,8-cineole (0.0167 mg cm(-3) ). Moderate toxicity was produced by camphene, 3-carene, (-)-menthone, (+)-α-pinene, (+)-β-pinene, α-terpineol and (-)-α-thujone (0.0215-0.0388 mg cm(-3) ). Against adult O. strigicollis, dichlorvos (LD50 9.0 × 10(-10) mg cm(-3) ) was the most toxic fumigant, whereas the LD50 values of these compounds ranged from 0.0127 to >0.23 mg cm(-3) . Based upon the selective toxicity ratio, the compounds described are more selective than dichlorvos. The basil oil compounds described merit further study as potential insecticides for control of T. palmi in greenhouses because of their generally lower toxicity to O. strigicollis and their greater activity as a fumigant than dichlorvos.

Toxicity of Cassia and Cinnamon Oil Compounds and Cinnamaldehyde-Related Compounds to <I>Sitophilus oryzae</I> (Coleoptera: Curculionidae)

The toxicity to adult Sitophilus oryzae (L.) (Coleoptera: Curculionidae) of two cassia oils (Especial and true), four cinnamon oils (technical, #500, bark, and green leaf), and (E)-cinnamaldehyde and its 41 structurally related compounds was examined by residual and vapor-phase toxicity bioassays. Results were compared with those of dichlorvos. In residual bioassays, cassia and cinnamon oils exhibited good insecticidal activity. Based on 48-h LD50 values, the toxicity of allyl cinnmate (0.0003 mg/cm2) was comparable with that of dichlorvos (0.00025 mg/cm2). Potent insecticidal activity also was observed with benzaldehyde, beta-caryophyllene, cinnamonitrile, hydrocinnamyl acetate, (E)-4-hydroxycinnamic acid, and alpha-terpineol (LD50 = 0.003-0.009 mg/cm2). Structure-activity relationships indicate that types of functional groups rather than hydrophobicity or vapor pressure parameters seem to play a role in determining the toxicities to adult S. oryzae. In vapor-phase toxicity tests with weevils, these compounds were more effective in closed containers than in open ones. These results indicate that the effect of the compounds was largely a result of action in the vapor phase. Cassia and cinnamon oils and test compounds described merit further study as potential fumigants for the control of S. oryzae because of their greater activity as a fumigant.

Fumigant toxicity of cassia bark and cassia and cinnamon oil compounds to Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae)

The toxicity to adults of the American house dust mite, Dermatophagoides farinae, and the European house dust mite, Dermatophagoides pteronyssinus, of cassia bark and cassia and cinnamon oil compounds was examined using residual contact and vapour-phase toxicity bioassays. Results were compared with those of the currently used acaricides: benzyl benzoate and dibutyl phthalate. The acaricidal principles of cassia bark were identified as (E)-cinnamaldehyde and salicylaldehyde. In fabric-circle residual contact bioassays with adult D. farinae, salicylaldehyde (17.3 mg/m(2)) and (E)-cinnamaldehyde (25.8 mg/m(2)) were 2.5 and 1.7 times more toxic than benzyl benzoate (43.7 mg/m(2)), respectively, based on 24-h LD(50) values. The acaricidal activity was more pronounced in benzaldehyde, menthol, alpha-terpineol, and thymol (70.8-234.3 mg/m(2)) than in dibutyl phthalate (281.0 mg/m(2)). Against adult D. pteronyssinus, salicylaldehyde (17.3 mg/m(2)) and (E)-cinnamaldehyde (19.3 mg/m(2)) were 2.4- and 2.2-fold more active than benzyl benzoate (41.9 mg/m(2)). The toxicity of benzaldehyde, menthol, alpha-terpineol, and thymol (75.3-179.2 mg/m(2)) was higher than that of dibutyl phthalate (285.1 mg/m(2)). In vapour-phase toxicity tests with adult D. farinae, the test compounds described were much more effective in closed--but not in open--containers, indicating that the effect of these compounds was largely a result of action in the vapour phase.

Toxicity of Atractylon and Atractylenolide III Identified inAtractylodes ovataRhizome toDermatophagoides farinaeandDermatophagoides pteronyssinus

The acaricidal activity of materials derived from rhizome of Atractylodes ovata (Atractylodes macrocephala) toward adult Dermatophagoides farinae and Dermatophagoides pteronyssinus was examined using fabric-circle residual contact and vapor-phase toxicity bioassays. Results were compared with those of the currently used acaricides: benzyl benzoate, dibutyl phthalate, and N,N-diethyl-m-toluamide (Deet). The active principles of A. ovata rhizome were identified as the sesquiterpenoids, atractylenolide III (1) and atractylon (2), by spectroscopic analysis. In fabric-circle residual contact bioassays with adult D. farinae, atractylenolide III (LD50, 103.3 mg/m2) and atractylon (136.2 mg/m2) were five and four times more toxic than Deet and 1.7- and 1.3-fold more active than dibutyl phthalate, respectively, based on 24 h LD50 values. These compounds were less toxic than benzyl benzoate (LD50, 45.8 mg/m2). Against adult D. pteronyssinus, atractylenolide III (LD50, 73.8 mg/m2) and atractylon (72.1 mg/m2) were eight times more active than Deet and 2.5-fold more toxic than dibutyl phthalate. These compounds were slightly less effective than benzyl benzoate (LD50, 46.0 mg/m2). In vapor-phase toxicity tests with both mite species, atractylenolide III and atractylon were effective in closed but not in open containers. These results indicate that the effect of these sesquiterpenoids was largely a result of action in the vapor phase. Naturally occurring atractylenolide III and atractylon merit further study as potential house dust mite control agents or leads because of their great activity as a fumigant.

Toxicity of <I>Myristica fragrans</I> Seed Compounds Against <I>Blattella germanica</I> (Dictyoptera: Blattellidae)

The insecticidal constituents of hexane-soluble fraction from a methanolic extract of the seeds from Myristica fragrans (Myristicaceae) against adult females of Blattella germanica (L.) (Dictyoptera: Blattellidae) were analyzed by gas chromatography and gas chromatography-mass spectrometry. The insecticidal activity of 13 Myristica seed compounds against female B. germanica was examined by using the filter-paper contact toxicity and vapor phase toxicity bioassays. Results were compared with those of the other 23 known compounds of Myristica seed and currently used insecticides: dichlorvos, deltamethrin, permethrin, and propoxur. In contact toxicity tests using female B. germanica, (IS)-(-) -beta-pinene (0.06 mg/cm2) was the most toxic insecticide, based on 24-h LD50 values. The insecticidal activity of this compound was comparable with that of permethrin (0.05 mg/cm2). (1R)-(+) -Camphor, (1S)-(-) -camphor, dipentene, (1R)-(+) -3-pinene, and (+)-alpha-terpineol (0.10-0.14 mg/cm2) were more toxic than propoxur (0.19 mg/cm2). (E)-Sabinene hydrate and propoxur were almost equitoxic. Potent insecticidal activity also was observed with (R)-(+) -citronellal, (S)-(-) -citronellal, (R)-(-) -alpha-phellandrene, (1S)-(-) -alpha-pinene, (1R)-(+) -alpha-pinene, and safrole (0.27-0.48 mg/cm2). In vapor phase toxicity tests, the compounds tested were effective in closed but not in open containers. These results indicate that the effect of these compounds was largely a result of action in the vapor phase. Myristica seed compounds described merit further study as potential insecticides or as leads for the control of cockroaches.

Toxicity ofMyristica fragransSeed Compounds AgainstBlattella germanica(Dictyoptera: Blattellidae)

The insecticidal constituents of hexane-soluble fraction from a methanolic extract of the seeds from Myristica fragrans (Myristicaceae) against adult females of Blattella germanica (L.) (Dictyoptera: Blattellidae) were analyzed by gas chromatography and gas chromatography-mass spectrometry. The insecticidal activity of 13 Myristica seed compounds against female B. germanica was examined by using the filter-paper contact toxicity and vapor phase toxicity bioassays. Results were compared with those of the other 23 known compounds of Myristica seed and currently used insecticides: dichlorvos, deltamethrin, permethrin, and propoxur. In contact toxicity tests using female B. germanica, (1S)-(-)-β-pinene (0.06 mg/cm2) was the most toxic insecticide, based on 24-h LD50 values. The insecticidal activity of this compound was comparable with that of permethrin (0.05 mg/cm2). (1R)-(+)-Camphor, (1S)-(-)-camphor, dipentene, (1R)-(+)-β-pinene, and (+)-α-terpineol (0.10–0.14 mg/cm2) were more toxic than propoxur (0.19 mg/cm2). (E)-Sabinene hydrate and propoxur were almost equitoxic. Potent insecticidal activity also was observed with (R)-(+)-citronellal, (S)-(-)-citronellal, (R)-(-)-α-phellandrene, (1S)-(-)-α-pinene, (1R)-(+)-α-pinene, and safrole (0.27–0.48 mg/cm2). In vapor phase toxicity tests, the compounds tested were effective in closed but not in open containers. These results indicate that the effect of these compounds was largely a result of action in the vapor phase. Myristica seed compounds described merit further study as potential insecticides or as leads for the control of cockroaches.

Contact and fumigant toxicity of oriental medicinal plant extracts against Dermanyssus gallinae (Acari: Dermanyssidae)

The acaricidal activity of methanolic extracts from 40 oriental medicinal plant species and a steam distillate of Cinnamomum camphora towards poultry house-collected adult Dermanyssus gallinae De Geer was examined using direct contact and vapour phase toxicity bioassays. Results were compared with those of 15 acaricides currently used. In filter paper contact toxicity bioassays using adult D. gallinae, C. camphora steam distillate (0.0051 mg cm −2) was the most toxic material, followed by extracts from Asarum sieboldii var. seoulens whole plant, Eugenia caryophyllata flower bud and Mentha arvensis var. piperascens whole plant (0.0063–0.0072 mg cm −2), based upon 24 h LD 50 values. The acaricidal activity of these four plant preparations was almost comparable to that of profenofos (LD 50, 0.003 mg cm −2) but less effective than dichlorvos (LD 50, 0.0004 mg cm −2). The toxicity of Illicium verum fruit and Lysimachia davurica leaf extracts (0.09 mg cm −2) was almost comparable to that of benfuracarb, prothiofos, propoxur and fenthion (0.053–0.070 mg cm −2). In vapour phase toxicity tests, these plant preparations were more effective in closed containers than in open ones, indicating that the mode of delivery of these plant extracts was largely a result of action in the vapour phase. Plants described herein merit further study as potential D. gallinae control agents.

Toxicity of spray and fumigant products containing cassia oil to Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae)

The toxicity of formulations of oil of cassia, Cinnamomum cassia Blume, (20 and 50 g L(-1) sprays and 100% oil-based fumigant) to adult Dermatophagoides farinae Hughes and D. pteronyssinus Trouessart was examined using contact and vapour-phase toxicity bioassays. Results were compared with the lethal activity of three commercial acaricides: benzyl benzoate, dibutyl phthalate and diethyl-m-toluamide (deet). The contact toxicity of cassia oil to both dust mite species was comparable with that of benzyl benzoate but was higher than that of the other two acaricides. Sprays containing 20 and 50 g L(-1) cassia oil were effective against both mite species when applied to fabric, glass, paper, plastic, tin or wood substrates. Applications of the 50 g L(-1) spray to different space volumes and surface areas determined that 50-60 mg of cassia oil was needed to control dust mites in 3.4 m(3) or in 1 m(2). In tests with fumigant devices, toxicity varied according to the thickness of non-woven fabric covering the device, the exposure time, the number of fumigant devices used and the volume of the space sprayed. Fumigant toxicity to adult D. pteronyssinus was more pronounced with devices enclosed in thinner (40 microm) versus thicker (45 or 50 microm) non-woven fabric covers. A single fumigant device with a 40 microm thick non-woven fabric cover resulted in substantial control in a space of 0.05 m(3) but exhibited only moderate to weak control in spaces >or= 0.097 m(3) at 4 days after application. Two fumigant devices gave 88% mortality in a space of 1.73 m(3). Cassia oil applied as sprays or in fumigant devices appears to provide effective protection of humans from house dust mites.

Toxicity of Bisabolangelone from Ostericum koreanum Roots to Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae)

The acaricidal activity of materials derived from the roots of Ostericum koreanum (Apiaceae) toward adults of Dermatophagoides farinae and Dermatophagoides pteronyssinus was examined by direct contact and vapor phase toxicity bioassays. Results were compared with those of three acaricides: benzyl benzoate, dibutyl phthalate, and N,N-diethyl-m-toluamide (DEET). The active principle was identified as the sesquiterpenoid bisabolangelone by spectroscopic analysis. In fabric-piece contact toxicity bioassays using adult D. farinae, bisabolangelone (1.88 microg/cm2) was more toxic than benzyl benzoate (11.91 microg/cm2), DEET (62.20 microg/cm2), or dibutyl phthalate (79.54 microg/cm2), based on 24-h LD50 values. Against adult D. pteronyssinus, bisabolangelone (1.79 microg/cm2) was similarly more active than benzyl benzoate (9.65 microg/cm2), DEET (64.45 microg/cm2), and dibutyl phthalate (77.79 microg/cm2). In vapor phase toxicity tests with both mite species, bisabolangelone was equitoxic in closed versus open containers. These results indicate that bisabolangelone was largely toxic through contact action. Bisabolangelone merits further study as a potential contact acaricide or lead for the control of house dust mites.

Acaricidal activities of paeonol and benzoic acid from Paeonia suffruticosa root bark and monoterpenoids against Tyrophagus putrescentiae (Acari: Acaridae)

The acaricidal activities of paeonol (2'-hydroxy-4'-methoxyacetophenone) and benzoic acid identified in the root bark of tree peony, Paeonia suffruticosa Andrews, against copra mite, Tyrophagus putrescentiae (Schrank), adults were examined using direct contact and vapour phase toxicity bioassays and compared with those of cinnamyl acetate, cinnamyl alcohol and 37 monoterpenoids as well as the acaricides benzyl benzoate, dibutyl phthalate and N,N-diethyl-m-toluamide (DEET). Based on LD(50) values in fabric piece contact toxicity bioassays, the acaricidal activities of benzoic acid (4.80 microg cm(-2)) and paeonol (5.29 microg cm(-2)) were comparable to that of benzyl benzoate (4.46 microg cm(-2)) but more pronounced than those of DEET (30.03 microg cm(-2)) and dibutyl phthalate (25.23 microg cm(-2)). In vapour phase toxicity bioassays, paeonol and benzoic acid were much more effective in closed containers than in open ones, indicating that the effects of these compounds were largely due to action in the vapour phase. As judged by 24 h LD(50) values, (1S)-(-)-verbenone (7.42 mg per disc) was the most toxic fumigant, followed by (1S)-(-)-camphor, (S)-(+)-carvone, (R)-(-)-linalool and (+/-)-camphor (10.45-18.18 mg). Potent fumigant toxicity was also observed with paeonol, (2S,5R)-(-)-menthone, (+/-)-citronellal, benzoic acid, (1S,4R)-(-)-alpha-thujone and (R)-(+)-pulegone (25.10-34.63 mg). Neither benzyl benzoate, DEET nor dibutyl phthalate caused fumigant toxicity. Paeonia root bark-derived materials, particularly paeonol and benzoic acid, as well as the monoterpenoids described, merit further study as potential acaricides or as leads for the control of T. putrescentiae.

Vapor Phase Toxicity of Plant Essential Oils to <I>Cadra cautella</I> (Lepidoptera: Pyralidae)

The toxicities of 44 plant essential oils against larvae of Cadra cautella (Walker) were examined using direct contact and vapor phase toxicity bioassays and compared with the lethal activity of chlorpyrifos-methyl, diazinon, dichlorvos, and fenthion, four widely used organophosphorus insecticides. Responses varied according to plant material used and exposure dose and time. In a filter paper contact toxicity bioassay, potent toxicity was produced from buchu leaf, niaouli, and rosemary oils at 2.4 mg/cm2 and armoise, cypress, galbanum, and mace oils at 4.7 mg/cm2. In vapor phase toxicity bioassays with larvae, cypress, galbanum, niaouli, and rosemary oils were much more effective in closed containers than in open containers, indicating that the lethal effects of these oils were largely because of action in the vapor phase. As judged by 24-h LC50 values, potent fumigant action was observed with niaouli oil (64.7 mg/liter air) and rosemary oil (64.6 mg liter/air). Cypress and galbanum oils exhibited weak fumigant activity. These essential oils were less active than dichlorvos (0.86 mg/liter air). Little or no fumigant action was observed with chlorpyrifos-methyl, diazinon, and fenthion. Essential oils described herein, particularly niaouli and rosemary oils, merit further study as potential larvicides for the control of C. cautella.

Ovicidal and adulticidal activities of Cinnamomum zeylanicum bark essential oil compounds and related compounds against Pediculus humanus capitis (Anoplura: Pediculicidae)

The toxicity of cinnamon, Cinnamomum zeylanicum, bark essential oil compounds against eggs and adult females of human head louse, Pediculus humanus capitis, was examined using direct contact and vapour phase toxicity bioassays and compared with the lethal activity of their related compounds, benzyl alcohol, cinnamic acid, cinnamyl acetate, 4-hydroxybenzaldehyde and salicylaldehyde, as well as two widely used pediculicides, d-phenothrin and pyrethrum. In a filter-paper contact toxicity bioassay with female lice at 0.25 mg/cm 2, benzaldehyde was 29- and 27-fold more toxic than pyrethrum and d-phenothrin, respectively, as judged by median lethal time (LT 50) values. Salicylaldehyde was nine and eight times more active than pyrethrum and d-phenothrin, respectively. Pediculicidal activity of linalool was comparable with that of d-phenothrin and pyrethrum. Cinnamomum bark essential oil was slightly less effective than either d-phenothrin or pyrethrum. Benzyl alcohol and ( E)-cinnamaldehyde exhibited moderate pediculicidal activity. After 24 h of exposure, no hatching was observed with 0.063 mg/cm 2 salicylaldehyde, 0.125 mg/cm 2 benzaldehyde, 0.5 mg/cm 2 Cinnamomum bark essential oil, 1.0 mg/cm 2 ( E)-cinnamaldehyde, and 1.0 mg/cm 2 benzyl cinnamate. Little or no ovicidal activity was observed with d-phenothrin or pyrethrum. In vapour phase toxicity tests with female lice, benzaldehyde and salicylaldehyde were much more effective in closed containers than in open ones, indicating that the mode of delivery of these compounds was largely due to action in the vapour phase. Neither d-phenothrin nor pyrethrum exhibited fumigant toxicity. Cinnamomum bark essential oil and test compounds described merit further study as potential pediculicides or ovicides for the control of P. h. capitis.

Vapor Phase Toxicity of Marjoram Oil Compounds and Their Related Monoterpenoids to Blattella germanica (Orthoptera: Blattellidae)

The toxicity of marjoram, Origanum majorana L., oil, 41 monoterpenoids, and 2 sesquiterpenoids against adult females of the German cockroach, Blattella germanica L., was examined using direct contact and vapor phase toxicity bioassays and compared with those of deltamethrin, dichlorvos, permethrin, and propoxur, four commonly used insecticides. In a filter-paper contact toxicity bioassay, the adulticidal activities of pulegone (0.06 mg/cm2), (+/-)-camphor (0.07 mg/cm2), and verbenone (0.07 mg/cm2) were comparable to that of permethrin (0.05 mg/cm2) but more pronounced than that of propoxur (0.18 mg/cm2), as judged by the 24-h LC50 values. These compounds were less effective than either deltamethrin (0.013 mg/cm2) or dichlorvos (0.007 mg/cm2). The toxicity of marjoram oil, thymol, alpha-terpineol, (-)-alpha-thujone, linalool, 1,8-cineole, (-)-camphor, and (+)-carvone, ranging from 0.08 to 0.18 mg/cm2, was higher than that of propoxur. In vapor phase toxicity tests, verbenone (11.48 mg/L air) was the most toxic compound followed by (-)-alpha-thujone (18.43 mg/L of air), thymol (18.76 mg/L of air), alpha-terpineol (21.89 mg/L of air), (+/-)-camphor (24.59 mg/L of air), linalool (26.20 mg/L of air), and marjoram oil (38.28 mg/L of air) on the basis of the 24-h LC50 values. Dichlorvos (0.07 mg/L of air) was the most potent fumigant. Structure-activity relationships indicate that structural characteristics, such as degrees of saturation and types of functional groups rather than types of carbon skeleton, and hydrophobicity and vapor pressure parameters appear to play a role in determining the monoterpenoid toxicities to adult B. germanica. Marjoram oil and the monoterpenoids described merit further study as potential fumigants or leads for the control of B. germanica.