Effects of solvents on the insecticidal efficacy of spray formulation against houseflies, mosquitos and cockroaches were determined. Among the solvents examined, kerosene with its boiling point of 200°C to 250°C was relatively more effective than others. The gas chromatographic analysis showed the main components of the effective kerosene were paraffins such as dodecane, tridecane and tetradecane. The detailed comparison of the insecticidal efficacy was conducted by employing various paraffins, and tetradecane was found most effective for knockdown efficacy against all the insects. Each paraffin showed different killing efficacy against different insects: Tetradecane showed the strongest killing effect against mosquitos and cockroaches whereas octane to dodecane showed the strongest killing effect against houseflies. The difference in knockdown and killing efficacy against houseflies was considered to be caused by the different behavior of the particles of each paraffin in the air after sprayed.

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Photodegradation of (1R, cis, αRS)- and (1R, trans, αRS)-isomers of Cypermethrin [(RS)-α-cyano-3-phenoxybenzyl (1RS)-cis, trans-3-(2, 2-dichlorovinyl)-2, 2-dimethylcyclopropanecarboxylate] in water and on soil surface was studied, using 14C preparations labeled separately at the cyclopropyl C-1, cyano or benzyl ring. The cis-isomer was photodecomposed 1.4-1.7 times faster in sunlight than the trans-isomer in water. The half-life of the cis-isomer was 2.3-2.6 days in distilled water and 1ppm humic acid aqueous solution, and 0.6-0.7 day in natural river and sea water, and <0.5 day in 2% aqueous acetone. A triplet photosensitizer acetone together with the naturally occurring substances in river and sea water enhanced the photodegradation of both isomers. On three kinds of soil surface, both isomers were rapidly photodegraded with the initial half-life of 0.6-1.9 days. The photoreactions involved were: 1R/1S and cis/trans isomerization of the cyclopropane ring, cleavage of the ester or diphenyl ether linkage, oxidation of the CHO group to the COOH group, hydration of the CN group to the CONH₂ group, hydrolysis of the CONH₂ group to the COOH group, oxidative cleavage of the halogenated side chain, dehalogenation, intramolecular cyclization to form γ-or δ-lactone, and photomineralization of the cyclopropyl C-1, cyano and benzyl ring to ¹⁴CO₂.

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Hydrolysis of (1R, cis, αRS)- and (1R, trans, αRS)-isomers of Cypermethrin [(RS)-α-cyano-3-phenoxybenzyl (1RS)-cis, trans-3-(2, 2-dichlorovinyl)-2, 2-dimethylcyclopropanecarboxylate] was studied in buffer solutions at pH 3.0, 7.0 and 11.0, and in natural river and sea water at 15°C, 25°C, 40°C and 55°C under laboratory conditions. For making suitable approximations, the expressions for k_A, k_N and k_B of Eq. (1) were calculated, using values of k_H at three pH's. k_H=k_A[H⁺]+k_N+k_B[OH^-] (1). The pH-rate profile thus obtained showed that hydrolysis of both isomers proceeded predominantly through neutral (pH independent) and base-catalyzed processes in the regions below pH 5.0 and above pH 7.0, respectively, whereas both reactions occurred between pH 5.0 and 7.0. The trans-isomer was hydrolyzed approximately 1.2-1.7 times faster than the cis-isomer at any pH tested between 25°C and 50°C. The rates of hydrolysis of both isomers in buffer solutions were similar to those in one sample of river and one sample of sea water. The cleavage of the ester linkage proceeded more rapidly than the hydration of the CN group at any pH and temperature tested.

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A new soil fungicide, which have a plant growth regulating activity, methasulfocarb [S-(4-methylsulfonyloxyphenyl) N-methylthiocarbamate, Kayabest^®, NK-191], promoted the root elongation of rice seedlings in water culture. The maximum elongation was obtained at its concentration of 25, 50, 100ppm, when the roots grew 1.5 times longer than those of untreated control. The elongation of roots was also promoted in the nursery soil treated with methasulfocarb. Methasulfocarb 10% dust, applied in soil, was effective to prevent the development of murenae, the acute wilt symptom of rice seedlings, in nursery stage. The application of methasulfocarb 10% dust at the rate of 8g (800mg a. i.) per 5l soil prevented the spindly growth of rice seedlings by inhibiting the excess growth of primary leaf sheaths. The seedlings in treated plots showed a greater top dry weight/plant height ratio and a smaller top dry weight/root dry weight ratio than those in untreated plots. Methasulfocarb treated plots provided the substantial and good quality rice seedlings, which enhanced the elongation of newly developing roots and exhibited a high rooting ability at low temperatures and a high geotropic curvature response when transplanted. The seedlings quickly developed their own root system in paddy soil immediately after transplantation and continued healthy growth and development in the early stage of rice plant after transplantation under flooded condition.

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Miticidal activity of the surfactants of anhydrosorbitol type on the carmine mite was investigated. These surfactants were effective against its female adults but not so effective against its eggs. No relationship was found between the Gabon chain length in the alkyl base of surfactants and the miticidal activity. On the contrary the less amount of ethylene oxide developed greater activity. The contact angle and the surface tension of the solution were not correlated with the mortality. A thin and consecutive layer of surfactants on the cuticle of the mite was prepared at a higher concentration and a lower HLB (Hydrophilic Lipophilic Balance) of surfactants. This fact suggested there existed a relationship between the condition of surfactant deposition and the mortality. Death was due to suffocation by depositing of surfactants on the cuticle.

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The metabolic fate of ¹⁴C-guazatine triacetate (¹⁴C-GZ-TA) in male rats was investigated. Bioavailability of GZ-TA, orally given 3 or 30mg/kg, was 8 to 14%. The intravenous dose of 3mg/kg ¹⁴C-GZ-TA was eliminated primarily into urine as hydrophilic metabolites and secondarily into feces mainly as GZ. The primary target organ for ¹⁴C was kidney, where the major ¹⁴C-residues were identified as 1, 1′-iminodi(octamethylene)-8-amino-8′-guanidine, GZ, and 1, 1′-iminodi(octamethylene)diamine. The deamidination of GZ was a primary mode of GZ-biotransformation in rats but it was not significantly mediated by either the hydrolysis or the transamidination to glycine and ornithine.

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Residues of chlorpyrifos (O, O-diethyl-O-3, 5, 6-trichloro-2-pyridyl phosphorothioate) and its oxygen analog (O, O-diethyl-O-3, 5, 6-trichloro-2-pyridyl phosphate) were determined in dates following the application of Dursban^® on palm trees by a gas chromatographic method. Residues of chlorpyrifos decreased sharply within 2 weeks after application, but detectable amounts remained up to 8 weeks. The oxygen analog of chlorpyrifos seemed to be more persistent than chlorpyrifos itself. To keep fruits clean from exessive contamination by chlorpyrifos, the shortest waiting period of 8 weeks between insecticide application and fruit harvest is recommended.

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The metabolic fate of fungicide MAFA [ammonium iron methanearsonate; (CH₃AsO₃)_m Fe_n·NH₄] was studied in three types of siols under moist conditions. The monomethylarsenic (MM-As) moiety of MAFA degraded with a half-life of 22-32 days. Inorganic-arsenic (Inorg-As) was interpreted as a terminal product due to its uninterrupted increase in amount with time. There was a remarkable difference in the residual amount of dimethyl-arsenic (DM-As) products depending on the soil type. Degradation rates of dimethylarsinic acid and trimethylarsine oxide were also highly dependent on the soil type. The rate and the direction of MAFA transformation in a soil did not significantly change when its microbial population was replaced with other's. The effects of soil moisture and exogenous glucose on MAFA or DSMA (disodium methanearsonate) transformation were examined. Volatile-As products were observed in glucose-amended soils under moist and flooded conditions, and trimethylarsenic (TM-As) was found to be their principal component.

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Metabolism of isofenphos (O-[1-¹⁴C]ethyl O-2-isopropoxycarbonylphenyl N-isopropylphosphoramidothioate) was examined under in vitro conditions of rat liver. In each fraction of mitochondria, microsomes and supernatant, isofenphos was metabolized enzymatically with NADPH, and the formation of polar metabolites was especially accelerated in the microsome-NADPH system. When the metabolites were partitioned between benzene and water, isofenphos-oxon and aminoisofenphos were identified as benzene soluble metabolites, and O-ethyl O-2-isopropoxycarbonylphenyl hydrogen phosphorothioate, O-ethyl O-2-isopropoxycarbonylphenyl hydrogen phosphate, O-ethyl hydrogen N-isopropylphosphoramidothioate and O-ethyl hydrogen N-isopropylphosphoramidate as water soluble metabolites. Isofenphos was metabolized rapidly into O-ethyl hydrogen N-isopropylphosphoramidate through isofenphos-oxon by the microsome fraction of rat liver, but it was unlikely that isofenphos-oxon could accumulate in the presence of NADPH. The conversion to water soluble metabolites was more dominant in the cleavage of P-O-C(aryl) bond than in that of P-N linkage. None of benzene soluble metabolites inhibited insect acetylcholinesterase (AChE) at the concentration of 10^-7M.

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A number of 4-tert-butylbenzamides and anilides were synthesized and their preventive activity against rice blast (Pyricularia oryzae) was studied. It was found that N-methyl-4-tert-butylbenzanilides possessed high preventive activity, which was enhanced by substitution at the ortho-position of aniline ring with groups derived from the hydroxy group. 2′-Hydroxy and 2′-ethoxycarbonyloxy derivatives of N-methyl-4-tert-butylbenzanilide were found the most active compounds.

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The absorption, translocation and metabolism of [O-ethyl-1-¹⁴C] isofenphos were examined in Japanese cypress seedlings, Endlicher Cupressus obtusa K. KOCH. The recovery of radiocarbon applied was different according to the application site and absorption reached the maximum 30, 10 and 4 days after the application by the stem top, stem base and root application, respectively. Radiocarbon absorbed in the plant tissues was the highest when it was applied to the root. The application sites made a big difference in translocation of radiocarbon in the seedlings. When it was applied to the stem top, a greater part of radiocarbon remained at the application site and a slightly lower portion of the applied region, and the translocation to the root rarely occurred. In the stem base application, upward and downward translocations of radiocarbon were scarcely observed either. In the root application, the absorption and translocation were considerably high compared with the other applications. Fractionation of radiocarbon in the plant tissues showed that a major portion of radiocarbon was partitioned in the benzene layer, and the radiocarbon in the aqueous layer and unextractable residues was very small. The examination of radiocarbon in the benzene layer by thin-layer chromatography (TLC) disclosed that isofenphos-oxon was a main metabolite and O-ethyl O-2-isopropoxycarbonylphenyl phosphoramidothioate (aminoisofenphos) and two unknown substances were minor metabolites. The transformation of isofenphos to isofenphos-oxon took place easily in the seedlings, though the transformation rate depended on the application site, and isofenphos-oxon was persistent in the seedlings. In the aqueous layer, two metabolites, O-ethyl hydrogen N-isopropylphosphoramidothioate (desphenylisofenphos) and O-ethyl hydrogen N-isopropylphosphoramidate (desphenylisofenphos-oxon) were identified.

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Decomposition of thiophanate-methyl (TM) in grape homogenate was investigated. Decomposition characteristics of TM, whether in frozen (-20°C) storage or non-frozen (40°C) storage, showed no significant difference, but its rate of decomposition was much faster in non-frozen storage than in frozen storage. Among the predictable decomposition products tested, methyl benzimidazol-2-ylcarbamate (MBC), 1-(3-methoxycarbonylthioureido)-2-(3-methoxycarbonylureido) benzene (MMB) and dimethyl 4, 4′-(o-phenylene) bis (allophanate) (DPA) were formed from TM. But the sum of these decomposition products accounted for less than a half of the decomposed TM, and what happened to the other half remained unknown. The time-course study revealed that the decomposition of TM in the grape homogenate underwent two steps: one was a steep decomposition (T_1/2<0.5hr, at 40°C) occurring immediately after an addition of TM, when TM decomposed predominantly into unknown product (s) directly from TM and/or via MMB, and the other, a subsequent gradual decomposition occurring during storage either frozen (T_1/2=400hr) or non-frozen (T_1/2=1.8hr), when TM decomposed mainly into MBC and MMB, while the latter decomposed further to the products such as DPA and MBC, and to some unknown product (s). It was revealed that the first decomposition was through the oxidation of C=S of the TM molecule.

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In order to characterize the nature of Periplaneta austyalasiae, sex pheromone, interspecific behavioral and EAG tests were carried out using both P. austyalasiae and P. americana. A highly purified P. austyalasiae sex pheromone (G-7) was obtained for the tests and used together with P. americana sex pheromones [periplanone-A (PA) and periplanone-B (PB)]. Male P. austyalasiae positively responded to G-7 and PA, but not to PB in both tests. Male P. americana also behaviorally and electrophysiologically responded to G-7 as well as to his own pheromones. Owing to these results, P. austyalasiae sex pheromone was suggested to be a PA-like substance.

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[in Japanese]

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