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PubMed2005

Fumigant toxicity of the essential oils of some African plants against Anopheles gambiae sensu stricto.

The essential oils from 15 species of African plants selected by ethnobotanical considerations and field inspection (odour and presence of insects) were screened for fumigant toxicity to Anopheles gambiae s.s. in the laboratory. Essential oils from 6 species showed varying levels of toxicity, with Conyza newii (Compositae) and Plectranthus marruboides (Labiateae) being the most potent. Fifty compounds representing approximately 74% of the essential oil of C. newii were identified by GC-MS and GC-coinjection (for available standards). The major and some of the minor constituents of the two oils were assayed at different doses. Two compounds, from C. newii, perillaldehyde and perillyl alcohol, exhibited higher fumigant toxicity (LD50 = 1.05 x 10(-4) and 2.52 x 10(-4) mg cm(-3), respectively) than the parent oil (2.0 x 10(-3) mg cm(-3)). GC-MS analysis of the essential oil of P. marruboides gave results similar to that previously reported. Interestingly, none of its components were active, suggesting that the insecticidal activity of the oil results from either some of the minor components or as a blend effect of some of the major constituents.

Animals↗
PubMed2001

Efficacy and fumigation characteristics of ozone in stored maize.

This study evaluated the efficacy of ozone as a fumigant to disinfest stored maize. Treatment of 8.9tonnes (350bu) of maize with 50ppm ozone for 3d resulted in 92-100% mortality of adult red flour beetle, Tribolium castaneum (Herbst), adult maize weevil, Sitophilus zeamais (Motsch.), and larval Indian meal moth, Plodia interpunctella (Hübner) and reduced by 63% the contamination level of the fungus Aspergillus parasiticus Speare on the kernel surface. Ozone fumigation of maize had two distinct phases. Phase 1 was characterized by rapid degradation of the ozone and slow movement through the grain. In Phase 2, the ozone flowed freely through the grain with little degradation and occurred once the molecular sites responsible for ozone degradation became saturated. The rate of saturation depended on the velocity of the ozone/air stream. The optimum apparent velocity for deep penetration of ozone into the grain mass was 0.03m/s, a velocity that is achievable in typical storage structures with current fans and motors. At this velocity 85% of the ozone penetrated 2.7m into the column of grain in 0.8d during Phase 1 and within 5d a stable degradation rate of 1ppm/0.3m was achieved. Optimum velocity for Phase 2 was 0.02m/s. At this velocity, 90% of the ozone dose penetrated 2.7m in less than 0.5d. These data demonstrate the potential usefulness of using ozone in managing stored maize and possibly other grains.

Journal Article↗
PubMed2000

Cross-resistance of a chlorpyrifos-methyl resistant strain of Oryzaephilus surinamensis (Coleoptera: Cucujidae) to fumigant toxicity of essential oil extracted from Eucalyptus globulus and its major monoterpene, 1,8-cineole.

The fumigant toxicities of eucalyptus essential oil and 1,8-cineole, the major component of eucalyptus oil, were tested against a chlorpyrifos-methyl resistant strain and a reference strain of the sawtoothed grain beetle, Oryzaephilus surinamensis (L.). The resistant strain showed 1.9- and 2.2-fold higher tolerance against essential oil and 1,8-cineole fumigation toxicity, respectively, relative to the susceptible strain. The increased tolerance for the essential oil may be the result of cross-resistance. The resistance mechanisms in the resistant strain are discussed in relation to elevated detoxifying enzymes such as cytochrome P450 and esterases.

Journal Article↗
PubMed2000

Advantageous attributes of larval whitefringed weevil, Naupactus leucoloma (Coleoptera: Curculionidae) for bioassaying soil fumigants, and responses to pure and plant-derived isothiocyanates.

First instars of the soil-inhabiting whitefringed weevil, Naupactus leucoloma (Boheman), are a particularly good bioassay model for assessing volatile soil fumigants and biofumigants. Eggs are readily obtained and can be stored for long periods with larvae hatched on demand and the first instar is non-feeding, surviving without food or shelter. Longevity varies with temperature, but readily accommodates the period required to conduct bioassays without appreciable mortality of untreated controls. In vitro bioassays of pure methyl isothiocyanate, the active ingredient from metham sodium soil fumigant, and the less volatile 2-phenylethyl isothiocyanate, sensitively detected differences in toxicity and effects of temperature. Bioassay of volatiles emitted from hydrolysed tissue of various isothiocyanate-producing Brassica plants revealed widely varying toxicity effects, indicating that bioassays with N. leucoloma are a sensitive and relevant indicator of the potential of different plants for biofumigation of soil-borne pest organisms.

Animals↗
PubMed2001

Development of a methyl bromide collection system for fumigated farmland.

Recent research has indicated that up to 73% of the methyl bromide (MeBr) applied to agricultural farmland is ultimately emitted to the atmosphere despite the practice of complete coverage of the fields with polyethylene (PE) tarp. To reduce the emission of MeBr, several techniques have been investigated. An alternative that has received little consideration is the collection and recycle or treatment of MeBr emissions. We investigated the potential of using a two-layer tarp system for collecting the MeBr. Laboratory experiments with a small two-layer diffusion reactor were conducted to determine the mass transfer coefficient (K) of MeBr through tarps and to validate a model of the collection system. For PE tarps K was 1.15 x 10(-6) m s-1 at 20 degrees C and 5.2 x 10(-6) m s-1 at 60 degrees C. K for so-called virtually impermeable films ranged from 4.6 x 10(-10) m s-1 to 1.3 x 10(-8) m s-1. The mathematical model was then used to simulate a full scale fumigant field application. Results indicate excellent agreement between the model, laboratory experiments, and previous field studies. Total emission from the field was a function of the air exchange rate through the swept volume between the two layers, the length of time the field is covered by the collection system, and the mass transfer coefficient of MeBr though the tarps. The results indicate that the proposed two-layer system can be very effective in collecting MeBr emissions from fumigated farmland.

Agriculture↗
PubMed1988

In vitro methylation of DNA by the fumigant methyl bromide.

Investigations have shown that the physical state of the DNA strongly influences the pattern of methylation observed when DNA or a substance containing DNA is treated with the fumigant methyl bromide. 1-Methyl-adenine and 7-methylguanine were identified, after hydrolysis, as the major methylated bases of DNA which had been treated in the solid state. 3-Methylcytosine, 3-methyladenine and 7-methyladenine were found as minor products. The overall methylation pattern was similar to that observed earlier for DNA of maize and wheat which had been fumigated. In contrast, when buffer solutions of DNA were treated with methyl bromide, the N-7 position of guanine was the major site and the N-3 position of adenine was the second most important site of methylation. This result corresponds to that previously observed in similar studies with buffer solutions of DNA and other methylating agents.

Animals↗
PubMed1982

Emission of hydrogen sulfide from sulfur dioxide-fumigated pine trees.

Pine (Pinus silvestris L.) trees subjected to relatively low concentration of SO(2) in the field emit H(2)S from the needles, as demonstrated by gas chromatographic analysis after preconcentration on a molecular sieve. H(2)S is the only reduced sulfurous compound emitted from SO(2) fumigated leaves. The emission is light and SO(2) concentration dependent. Pine trees in the field and in laboratory experiments continue to emit H(2)S several hours after the termination of prolonged SO(2) fumigation. The maximum emission rates observed from pine trees in the field and in laboratory experiments, 14 and 20 nanomoles per milligram chlorophyll per hour respectively, are about the activity expected for the sulfur assimilation pathway in the chloroplasts.

Journal Article↗
PubMedDate not supplied

[The use of insecticide fumigant canister to protect an insectarium and its residual effect against triatomine bugs, in laboratory conditions].

An insecticide fumigant canister based on synthetic pyrethroids and dichlorvos was employed against cockroaches and ants which were invading an insectarium used for rearing triatominae. After removal of the Triatominae, the canister was activated and found to kill all the invading insects within 48 hours. Possible residual action against triatomines was then monitored by a 24-hour exposure of eggs, nymphs and adults of Triatoma infestans, Panstrongylus megistus and Rhodnius neglectus in the treated insectarium. No ovicidal action was observed but some mortality of adults and nymphs of the three species was observed up to 72 hours after the fumigation.

Animals↗
PubMed2002

Soil fumigation with chloropicrin in Italy: experimental results on melon, eggplant and tomato.

Starting in 1999, seven experimental trials were carried out in Italy in order to evaluate the efficacy of chloropicrin (CP) (Tripicrin, a.i. 99% by wt) as alternative to methyl bromide for soil disinfestation. CP applied by shank injection at 30-40 g/m2 provided a satisfactory and consistent control of Fusarium wilt on melon and Verticillium wilt on eggplant, particularly in sandy soils. On melon against Fusarium wilt and on tomato against F. radicis lycopersici and Fusarium and Verticillium wilts CP at 40 or 60 g/m2 applied by drip irrigation at the concentration of 400 to 700 microliters/l or 850 microliters/l provided the best results. CP applied at 80 g/m2 with 60 mm of water (corresponding to 850 microliters/l) did not increase the efficacy of the soil fumigation treatment and, on tomato, was phytotoxic, causing sudden collapse of plants immediately after the transplant. The comparison of chloropicrin drip application under polyethylene, widely used in the past for methyl bromide soil fumigation, or under virtually gas impermeable film (VIF), to reduce atmosphere emissions, showed an increase of CP efficacy under VIF only reducing the dosages below 40 or 30 g/m2.

Cucumis↗
PubMed1975

[Resistance of tuberculosis mycobacteria in raw-dried and raw-fumigated sausages].

Studied was the resistance of Mycobacterium tuberculosis, Mycobact. bovinum, and Mycobact. avium in the nonperishable raw-dried and raw-fumigated saussages Koprivshtenska and Troyanska loukanka and Gornooryahovskanadenitsa, produced according to the requirements of the Bulgarian State Standards and the technologic instructions. It was found that the viability and pathogenicity of the tuberculosis mycobacteria in the raw-dried loukankas persist up to the 180th day from contamination, and in the raw-fumigated loukankas they were established up to the 150th day. The survival of bacteria in these saussages during long storage depended on the count of the microbial cells in the meat mass. At 120,000 cells per one gram of meat mass, some bacteria were found up to the 180th day, while at 1200 cells these persisted up to the 150th day.

Bulgaria↗
PubMed1963

INITIAL FIELD STUDIES IN UPPER VOLTA WITH DICHLORVOS RESIDUAL FUMIGANT AS A MALARIA ERADICATION TECHNIQUE. 1. GENERAL CONSIDERATIONS.

Laboratory and simulated field tests have shown that dichlorvos, a volatile insecticide, can be prepared in a solid formulation which releases the dichlorvos vapour over a period of several months at a relatively uniform rate high enough to kill adult anopheline mosquitos but low enough to have no effect on man and the higher animals.A field experiment is in progress in Wakara, Upper Volta, to evaluate the residual fumigant technique under practical field conditions. Chemical, biological, toxicological and epidemiological data obtained during the first nine months indicate that the method produced dichlorvos vapours in a concentration effective against mosquitos for 3 to 5 months per treatment, that the occupants of the treated dwellings showed no detectable effects from the insecticidal vapours, and that the malaria rates were reduced by 38%-55% among the population of the treated village as compared with a nearby untreated control village.

Africa↗
PubMed1963

INITIAL FIELD STUDIES IN UPPER VOLTA WITH DICHLORVOS RESIDUAL FUMIGANT AS A MALARIA ERADICATION TECHNIQUE. 3. TOXICOLOGICAL EVALUATION.

The residual fumigant technique involving the use of dichlorvos in the solid dispenser formulation employed in the study reported in this paper appears to offer no hazard to the occupants of houses treated at the rate of one dispenser per 500 cubic feet (14 m(3)) in so far as dichlorvos vapour toxicity is concerned. Even the maximum dosage rate tested (one dispenser per 60 cubic feet (1.7 m(3)) or 28 dispensers in a two-room house) did not produce observable effects on the occupants of the houses. This maximum rate far exceeds that necessary for malaria eradication operations, thereby affording an additional safety factor.

Africa↗
PubMed2001

Fumigant toxicity of volatile natural products from Korean spices and medicinal plants towards the rice weevil, Sitophilus oryzae (L).

The fumigant toxicity of various volatile constituents of essential oils extracted from sixteen Korean spices and medicinal plants towards the rice weevil, Sitophilus oryzae L (Coleoptera: Curculionidae), was determined. The most potent toxicity was found in the essential oil from Mentha arvensis L. var piperascens (LC50 = 45.5 microliters litre-1 air). GC-MS analysis of essential oil from M arvensis showed it to be rich in menthol (63.2%), menthone (13.1%) and limonene (1.5%), followed in abundance by beta-pinene (0.7%), alpha-pinene (0.6%) and linalool (0.2%). Treatment of S oryzae with each of these terpenes showed menthone to be most active (LC50 = 12.7 microliters litre-1 air) followed by linalool (LC50 = 39.2 microliters litre-1 air) and alpha-pinene (LC50 = 54.9 microliters litre-1 air). Studies on inhibition of acetylcholinesterase activity of S oryzae showed menthone to have a nine-fold lower inhibitory effect than menthol, despite menthone being 8.1-fold more toxic than menthol to the rice weevil. Different modes of toxicity of these monoterpenes towards S oryzae are discussed.

Acetylcholinesterase↗
PubMed1996

Safety assessment based on irrelevant toxicologic data: an extraordinary case of bromomethane used as a fumigant.

Bromomethane (BM) is a fumigant used in agriculture; it readily breaks down to bromide ion. WHO assessed the ADI of BM, at 1 mg/kg, using data on the toxicity of bromide. On the other hand, U.S. EPA used the observation of hyperplasia in the forestomach of rats given BM by gavage and arrived at a value of 0.0014 mg/kg. The validity of EPA's assessment is thus subject to question because of the data involved by (1) direct introduction of this volatile and reactive chemical to the GI by gavage and (2) using lesions in the rat forestomach which is absent in humans.

Animals↗
PubMed2001

Effects of methyl bromide fumigation on anhydrobiotic micrometazoans.

Anhydrobiotic organisms are well known for their resistance to extreme environmental conditions while in the inactive, ametabolic, state. This study confirms that this resistance also transfers to treatments with the fumigant methyl bromide. Live specimens of nematodes, rotifers, and tardigrades were found after 70 h of treatment with methyl bromide. Quantitative estimates of survival in the eutardigrade Richtersius coronifer revealed no difference between treated and untreated samples which had been kept dry for a short time. However, R. coronifer from samples collected 11 months before treatment had lower survival compared to samples collected shortly before the treatment. The fact that anhydrobiotic organisms escape treatments with biocides should be considered a serious problem, both for the food industry and from the perspective of human-mediated spread of organisms.

Animals↗
PubMed1995

Effect of Japanese mint (Mentha arvensis) oil as fumigant on nutritional quality of stored sorghum.

Japanese mint (Mentha arvensis) oil (JMO) can be used effectively as fumigant against Sitophilus oryzae in stored sorghum. The effect of JMO at a dose of 166 microliter/l of space on nutrient composition and protein quality was studied in infested and uninfested sorghum grains stored for 3 months. The results revealed non significant effect of JMO on gran moisture, total ash, crude fibre, crude fat, crude protein and fat acidity in infested and uninfested grains at the end of 3 months storage. The JMO treatment had small but significant effect on reducing and non-reducing sugars. The values of Protein Efficiency Ratio (PER) for uninfested JMO treated grains, infested JMO treated grains and for untreated control stored for 3 months were 1.11, 1.07 and 1.09, respectively against control casein diet for which it was 2.15.

Dietary Carbohydrates↗
PubMed1975

Determination of air movement in stored grain as a factor in dynamic dispersion and distribution patterns of gaseous pesticides (fumigants).

The new research reported herein was motivated by variations in distribution-persistence patterns of fumigant residues (BERCK, 1974). The current developmental program is still underway. In the meantime, measurement of picoliter amounts of SF6 in air by GC equipped with a Ni63 EC detector has been proven useful over an airflow range of 10(-4) to 50 mph, representing a factor of 500,000 in differences in air velocity. Diverse applications have been outlined herein. This is the first case on record where measurement of unassisted airflow in the interstitial air of stored grain has been successfully executed, and which enabled determination of airflow speeds in the range of 0.5 to 7.5 times 10(-4) mph (=3 to 45 inches per hour).

Air Movements↗
PubMed2005

Native Kenyan plants as possible alternatives to methyl bromide in soil fumigation.

Methyl bromide (CH3Br) is a biocidal fumigant used widely in crop production and commodity preservation worldwide. CH3Br escapes to the stratosphere and releases bromine atom (Br), which contributes to significant destruction of the ozone (O3). It is therefore necessary to explore alternatives to CH3Br that are environmentally safe and suitable for resource-poor African farmers. We present here the results of a study on the inhibitory activity of crude extracts from Kenyan medicinal plants against three soil pathogens, Fusarium oxysporum, Alternaria passiflorae, and Aspergillus niger. Crude organic extracts of Warburgia ugandensis Sprague, Azadirachta indica A. Juss, Tagetes minuta and Urtica massaica were active against all soil pathogens, while those from U. massaica were not. Chromatographic purification of the crude extract of W. ugandensis provided two pure compounds, muzigadial (1) and muzigadiolide (5). The minimum inhibitory concentration (MIC value) for muzigadial (1) ranged from 5 to 100mug/ml. Muzigadiolide (5) was not active. Greenhouse tests of W. ugandensis extracts against F. oxysporium pathogen showed the most effective inhibitory concentration to be at least 5 mg/ml. Quantitative structure-activity relationship (QSAR) models were used to rationalize the variation in biological activities of muzigadial (1), warburganal (2), polygodial (3), ugandensidial (4), muzigadiolide (5), azadirachtin (6), and CH3Br. The models were based on several molecular descriptors including LogP, van der Waals surface area (VDW(A)), van der Waals volume (VDW(v)), dipole moment, total energy, polarizability, and differences between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO gap).

Alternaria↗