Fungitoxicity of methoxychlor and fenitrothion and the environmental impact of their metabolites

Abstract

The soil fungi Mortierella pusilla, M. isabellina, and Trichoderma viride, and the aquatic fungus Saprolegnia parasitica were chosen as test organisms to study the fungitoxicity of the pesticides methoxychlor and fenitrothion and some of their known metabolites and derivatives. The inhibition of mycelial growth on agar plates was used as a criterion for toxicity and it was established that the inhibiting effect was fungistatic rather than fungicidal. The results, which indicate that some metabolites are more toxic than the parent pesticides, are reported in the form of dosage response relationships and a novel method of reporting such relationships is proposed.

Microbial toxicity of triclopyr and related herbicides

“…4. It was found earlier (Baarschers et al, 1980) that degradation products of two insecticides are considerably more toxic to fungi than the parent pesticides. Present results show the same trend.…”

“…Fungitoxicity measurements followed a well-established protocol (Ricardson and Miller, 1960;Baarschers et al, 1980) and results are summarized in Table I. The usual concentration range (3.1-400 ppm) had to be extended for the almost nontoxic amine salts, and solubility limitations prevented meaningful measurements on picloram.…”

“…Fungitoxicity, in terms of growth inhibition, was determined by the culture plate bioassay described earlier (Baarschers et al, 1980;Richardson and Miller, 1960). Thus, plates containing increasing doses of pesticide were inoculated in the center with standard agar plug inocula (9 mm) cut from previous plate cultures.…”

“…Trichloropyridinol (11) and 2,4-dichlorophenol (IV) were added to liquid medium in concentrations found to give 100% inhibition by the plate method and inoculated as above. These mixtures were kept on the shaker for periods of time sufficient to give normal growth in a set of controls as determined by maximum dry weight of mycelium (Baarschers et al, 1980). From test flasks in which no growth was observed, inocula were removed, rinsed with sterile distilled water, and placed on pesticide-free agar plates.…”

Detection of Fenitrothion and its Degradation Product 3-Methyl-4-nitrophenol in Water Environment

“…Therefore, 3M4NP has been brought under the review of the OECD (Organisation for Economic Co-operation and Development) HPV (High Production Volume) Chemicals Programme due to its genotoxicity presuming carcinogenicity (OECD, 1994). Because the oxon form of fenitrothion more strongly inhibits acetylcholinesterase, 3M4NP often shows stronger toxicity than fenitrothion (Baarschers et al, 1980). In addition, 3M4NP also shows higher MFP than fenitrothion (Kishida et al, 2010b).…”