Fumigation Method

This method is suitable for stored-product pests. The evaluation of toxic vapor is a somewhat similar operation. The insecticide is introduced into a sealed container along with the insects and mortality is recorded at different intervals. Various fumigation techniques were described by Busvine (1971), including (1) small-scale techniques for measuring the susceptibility of exposed insects and (2) semipractical tests using large fumigation chambers. 

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Application. The useflilness of any insecticide is substantially dependent upon its proper appHcation and this is deterrnined by the properties of the insecticide, the habits of the pest to be controlled, and the site of the appHcation to be made. The three general methods of applying insecticides are spraying, with water or oil as the principal carrier dusting, with a fine dry powder as the carrier and fumigation, where the insecticide is appHed as a gas (1). 

T. Cairns and J. Sherma, eds.. Comprehensive Analytical Profiles of Important Pesticides, CRC Press, Boca Raton, Fla., 1992, 304 pp. From the series ModemMethods for Pesticide Analysis, provides detailed information on properties and analytical methodology for nine prominent pesticides, pyrethroids, and fumigants in food. Includes formulations and uses, chemical and physical properties, toxicity data, and tolerances on various foods and feeds. Analytical information may be given in enough detail for methods to be carried out without having to consult additional Hterature sources. 

Heikes DL, Hopper ML. 1986. Purge and trap method for determination of fumigants in whole grains, milled grain products, and intermediate grain-based foods. J Assoc Off Anal Chem 69 990-998. 

P. C. Brookes, L. Landman, and D. S. Jenkin.son, Chloroform fumigation and the release of soil nitrogen a rapid extraction method to measure microbial biomass nitrogen in soil. Soil Biol. Biochem. 17331 (1985). 

The development of new fiber coatings in the near future should further improve the specificity of SPME and overcome some of the observed matrix effects. Quantification by stable isotope dilution gas chromatography/mass spectrometry (GC/MS) may assist in improving analytical performance. Along with the possible application of micro LC and capillary LC columns to in-tube SPME, the development of novel derivatization methods and the potential for the analysis of fumigant pesticides, SPME appears to be a technique with a future in the analysis of pesticide residues in food. 

Accessibility of the deposit to the insects by contact is the chief feature of the small vial method, but fumigant action cannot be eliminated entirely. In the case of DDT this has been found to be unimportant, for flies kept in the vials out of contact with the surface are not affected. But with 7-hexachlorocyclohexane or parathion there is a noticeable toxic effect. If the vials are stood upright, laid on the side, or hung upside down, there is a decrease in the mortality produced in the order given. The position on the side has been adopted because it avoids extremes and because practical use of an insecticide often involves limited but not accentuated ventilation. 

In the evaluation of ethylene dibromide as a soil fumigant, a sensitive procedure was needed for determining concentrations lower than 0.2 mg. per cubic inch in soil. When the method of Brenner and Poland was used, addition of a small quantity of acetic acid considerably increased the percentage of ethylene dibromide recovered. 

Comparatively little information is available in the literature on the determination of acrylonitrile in biological materials. Methods have been published for the determination of acrylonitrile in blood (Anderson and Harland 1980 Freshour and Melcher 1983) and urine (Houthuijs et al. 1982 Sakurai et al. 1978). Acrylonitrile was widely used in the past as a fumigant, and it is possible that methods used for the determination of other fumigants in biological materials (Walters 1986) could be adapted to the determination of acrylonitrile in such samples. 

Historically, measurement of the microbial biomass has been a tedious, time-consuming occupation involving staining and direct counting or use of culture media and enumeration of individual microbial communities. However, in the last 20 years, a suite of methods have been developed for more rapid assessment of the microbial biomass. These include the substrate-induced respiration method (Anderson and Domsch 1978), the chloroform fumigation-incubation method (Jenkinson and... 

Table 4 Knockdown efficacy of Metofluthrin coils against Culex quinquefasciatus (Bogor, Indonesia, field strain) using the large chamber free-flying method, 1 -h pre-fumigation...

Roughan et al. [10] have described a gas chromatographic method for the determination of total bromine (and bromide) originating as methyl bromide fumigant in soils (and crops). 

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