Effects of chlorcyclizine or phenobarbital on in vitro detoxication activity by larval wax moth gut homogenates

Herbivore-plant interactions: mixed-function oxidases and secondary plant substances

The mixed-function oxidases of a polyphagous insect larva (the southern armyworm, Spodoptera eridania) were found to be induced by a diversity of secondary plant substances. The induction proceeds rapidly and in response to a small quantity of secondary substance. Following induction, the larva is less susceptible to dietary poisoning. It is argued that mixed-function oxidases play a major role in protecting herbivores against chemical stress from secondary plant substances.

Insecticide solvents: interference with insecticidal action

Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations increase by more than threefold the microsomal N-demethylation of p-chloro N-methylaniline in midgut preparations of southern army-worm (Spodoptera eridania) larvae exposed orally to the test solvents. Under laboratory conditions, the same solvent mixtures exhibit a protective action against the in vivo toxicity of the insecticide carbaryl to the larvae. The data are discussed with respect to possible solvent-insecticide interactions occurring under field conditions and, more broadly, to potential toxicological hazards of these solvents to humans.

Metabolism of radiolabeled insecticides in insects and related arthropods: a critical study of various techniques

The metabolism of radiolabeled insecticides in insects and acarina is studied largely by coupling radiotracer techniques with analytical methods, such as TLC, paper and column chromatography, gel-permeation chromatography, and enzymatic assays. These techniques in various combinations yield both the identification and quantification of the metabolites. Other analytical methods such as gas chromatography or IR spectrometry may also be used to obtain additional support for identification of metabolites. In the absence of authentic chromatographic standards, however, NMR and mass spectrometry are necessary in the identification of the unknown compound. The quantity of the radiolabeled insecticide administered should be within the toxicological range of the insect. Therefore, the dosage-mortality response of the insect using unlabeled material should be determined. A dose should be selected that keeps insect mortality to a minimum in order to avoid complications in the computation of the balance data. The radiolabeled insecticide is usually applied topically to the insect. Alternately, the material may be administered by dipping in a solution containing the radiolabeled compound or by exposure to filter paper impregnated with radiolabeled material. Administration of the radiolabeled material by the oral route presents several problems. Sterile rearing conditions are mandatory to avoid contamination of treated diet with microorganisms. Some knowledge of the insect's feeding rhythm is desirable so that the labeled diet is given at peak feeding time. Synthetic diets should be adjusted to pH 7.0. These precautions minimize degradation of the insecticide in the diet prior to consumption by the insect. Precise doses of radiolabeled materials may be administered by injection. The technique is mainly useful in metabolism studies of intermediate materials resulting from the biotransformation of the parent compound.

Metabolic interactions among environmental chemicals and drugs

It is evident that metabolic interactions can occur among drugs, insecticides, food additives, carcinogenic hydrocarbons, and a variety of environmental chemicals. A common denominator governing these effects is the versatile nature of the liver microsomal enzymes that metabolize chemicals with diverse structures and biological activities, and the fact that these enzymes can be stimulated or inhibited by other chemicals administered simultaneously. The discovery of these particular enzymes in the 1950's laid the groundwork for the current research on metabolic interactions. Such research provides information that is helpful in the evaluation of the safety and efficacy of drugs and environmental chemicals, and suggests new directions for further research. Some examples are as follows.