Dispersion coefficients D resulting from Tsukuba soil-picric acid leaching system showed a large variance, but they had a tendency to increase with the pore-water velocity U, representing the regression equation D=0.46U-0.053, U>0.1cm/min. D seemed to be independent of U below 0.1cm/min and the average was 0.012cm²/min. A 3cm length soil column showed two peaks before and after the simulation peak, while a 27cm length soil column showed one peak before the simulation peak. This phenomenon is explicable by the wall effect. Konosu paddy soil-picric acid system resulted in 0.14cm²/min of D independent of U. The Freundlich's adsorption coefficients of picric acid and oxamyl were 3.84 and 0.33 in ppm unit and the indexes were 0.816 and 0.828, respectively. Tsukuba soil-oxamyl leaching system gave 0.008cm²/min of D at a low U 0.06cm/min, which was the similar value as Tsukuba soil-picric acid leaching system. This suggests that the soil types affect more greatly on the dispersion coefficient than the kind of leached chemicals.

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The vertical movement of oxamyl applied to the top soil was described by the differential equation consisting of dispersion coefficient, pore-water velocity, Freundlich's constants for adsorption, soil water content, soil stationary water ratio, soil bulk density, distance from the surface, and elution time. The exponential degradation rate obtained from an indoor experiment was also taken into account for the calculation. The pore-water velocity was shown to be positive for period of rain and negative for period of no rain reflecting evaporation of water from soil surface. The observed data for 19 days required different values of dispersion coefficient (D) for different stages of simulation, i. e., D=3.0cm²/hr for 24hr just after the application of oxamyl, D=0.2cm²/hr for each period of rain, and D=0.02cm²/hr for each period of no rain. The simulation shows that most of oxamyl stays in the top 20cm layer and very few reaches the layer below 60cm under the conditions of usual rainy season, although oxamyl shows a drastic vertical movement within the top 3.5cm layer.

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Steric and electronic parameters of acyl substituents of N-(3, 4-dichlorophenyl) acylamides were estimated from experimentally determined acid and base catalyzed hydrolytic rate constants according to Taft and Hancock. Variations in the hydrolytic rate of acylamides by an aryl acylamidase preparation derived from fresh leaves of the rice plant were quantitatively analyzed using the estimated steric and electronic parameters (E^c_s and σ*) for the acyl substituents. Steric effect of acyl substituents including the branching at α position to the carbonyl group was found to lower the enzymatic hydrolytic rate, whereas electron-withdrawing property was to enhance the rate of this series of acylamides.

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No morphological difference was found in the epithelial cells of midgut between the normal and the diflubenzuron-treated last instar larvae of the cabbage armyworm, Mamestra brassicae L. Diflubenzuron and polyoxin D strongly inhibited chitin synthesis in the peritrophic membranes of the midgut when glucosamine or N-acetylglucosamine was applied, as a precursor of chitin, either inside or outside the midgut. When UDP-N-acetylglucosamine was injected into the midgut with polyoxin D, chitin synthesis was blocked, but not with diflubenzuron. The results lead to the following speculation: UDP-N-acetylglucosamine would be formed from glucosamine or N-acetylglucosamine in the epithelial cells and then move to the outer face of the biomembranes of the cells to form chitin. Diflubenzuron may act as an inhibitor of the transport system of UDP-N-acetylglucosamine across biomembranes, since an accumulation of UDP-N-acetylglucosamine is known in insects treated with diflubenzuron. Na⁺-K⁺ ATPase and Ca²⁺-Mg²⁺ ATPase were not affected by the insecticide.

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Domoic acid isolated from a seaweed, Chondria armata, showed extremely strong insecticidal activity against cockroaches and houseflies. The minimum effective dose against the American cockroach by subcutaneous injection was 0.8μg/g. This compound also induced significant contraction of the hindgut excised from the American cockroach. The site of action may be the neuromuscular junction, similar to that of α-kainic acid. The structureactivity relationships of domoic and α-kainic acids and their analogs were also investigated. The synthetic analogs were useful tools for delineating the structurally essential requirement for the insecticidal activity.

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The behavior of herbicides CNP (chloronitrophen), molinate and simetryne in soil and in surface water was investigated by using a model paddy field (an ordinary culture and a bare ground) under the conditions of draining water at a controlled rate. Estimated half-life of herbicides CNP, molinate and simetryne in soil was 7-15 days, 5-20 days and 5-20 days, respectively. These herbicides detected in effluent water were 5-7ppb, 1300-1500ppb and 300-360ppb at the maximum concentration, respectively. It was estimated that the total amount which flowed out from the paddy field with surface water was 1.3-1.6% in CNP, 23-27% in molinate and 22-26% in simetryne of the applied one. The similar residue pattern of each herbicide in water was observed between an ordinary culture and a bare ground. Throughout this investigation, the highest concentration of CNP amino derivative observed in soil corresponded to 16% of the CNP applied first (a major portion of it was in the fraction of soil bound residue), and that in water below a detectable level.

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The degradation of a fungicide guazatine-triacetate (TA) was investigated in three agricultural soils (Kumagaya clay loam, Chiba loam, and Nagaoka clay loam) under upland or flooded conditions using two types of the ¹⁴C-labeled fungicide. When ¹⁴C-guazatine-TA was added to the soils, the fungicide was immediately and strongly adsorbed to soil particles to become resistant against microbial attack irrespective of soil types and incubation conditions. Consequently, the fungicide degraded extremely slowly and radioactive carbon dioxide was formed to a limited extent (1-5% of applied ¹⁴C). Since the loss of ¹⁴CO₂ appeared to be an essential factor for the disappearance of radiocarbon from the soils, the radiocarbon persisted for a long time period in all cases (half-life of ¹⁴C≥3.5 years). No degradation product was detected from all the soil extracts, and it seemed that almost all of the radiocarbon persisted in the soils was attributable to the presence of the intact fungicide. Investigations on the adsorption of ¹⁴C-guazatine from aqueous solution to Kumagaya and Chiba soils indicated that guazatine had high affinity for both soils, and in diluted solution the fungicide was completely adsorbed to soil particles (or no measurable amount of ¹⁴C-guazatine was contained in the solution). The quantity of guazatine held in this strong adsorption region was approximately 10mmol/kg for both soils, and this value was 1000 times greater than the burden of soil when guazatine was applied to the field at a normal recommended rate. The adsorption isotherms determined with or without hydrogen peroxide treatment and ¹⁴C-distribution among humic materials showed that ¹⁴C-guazatine was preferentially held in the soil inorganic fraction.

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Availability of “bound” ¹⁴C-guazatine soil residues to the soybean plant (Glycine Max var. Shiratori) and the rice plant (Oryza sativa var. Nihonbare) was investigated under laboratory conditions, using three different soils (Kumagaya clay loam and Chiba loam under upland conditions, and Nagaoka clay loam under flooded conditions) which were pretreated with 5ppm (on dry weight basis) of ¹⁴C-guazatine-triacetate (TA) for 26 weeks to produce bound ¹⁴C-guazatine soil residues. Soybean plants grown in Kumagaya and Chiba upland soils containing bound ¹⁴C-guazatine residues were divided into various plant parts to determine their ¹⁴C-content. Four weeks after planting, ¹⁴C-concentrations expressed on a dry tissue weight basis in each plant parts were less than one-fifth of the ¹⁴C-concentration in the surrounding soil. Total ¹⁴C-recovery from the aerial tissues and from the whole plant tissues were only 0.08 and 0.12% of the applied radiocarbon to the soils, respectively. Quantity of the radiocarbon translocated into soybean seeds 9 weeks after planting was extremely small, and a large portion of this radiocarbon did not seem to be of the intact fungicide. These data demonstrated that the bound soil residues were unavailable to the soybean plant. Bound ¹⁴C-guazatine residues in Nagaoka flooded soil were also unavailable to the rice plant, which absorbed only 0.13% of the total radiocarbon applied to the soil during a period of 4 weeks. When the root of a rice seedling was treated with a nutrient solution containing 5ppm of ¹⁴C-guazatine-TA, an extremely high concentration of radiocarbon was detected from the root (2700ppm, 7 days) presumably due to adsorption of ¹⁴C-guazatine on the root. On the other hand, radiocarbon was poorly translocated into shoots (7ppm, 7days), suggesting guazatine to be an inherently low-systemic fungicide. On the basis of the data obtained, it seemed that plants grown in the soil containing bound guazatine residues are not significantly contaminated by root uptake and subsequent translocation.

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The insecticidal activities of pyrethroids against the susceptible (LE) strain of the rice brown planthopper and the small brown planthopper were lower than the conventional carbamate insecticides, and were similar to or lower than those of malathion and fenitrothion. The malathion- and fenitrothion-resistant (Rm and Rf) strains of the rice brown planthopper did not show cross-resistance to allethrin, but did to resmethrin, permethrin, tetramethrin and fenpropathrin. The Rm and Rf strains of the small brown planthopper did not show cross resistance to pyrethrins, allethrin, permethrin and fenpropathrin, but a lesser degree of resistance was observed to furamethrin, resmethrin and tetramethrin. The insecticidal activities of fenvalerate against the rice brown planthopper, small brown planthopper, and green rice leafhopper were heightened with the increase in malathion resistance levels. The LD₅₀ values of fenvalerate in the rice brown planthopper, small brown planthopper and green rice leafhopper having 710-, 144- and 768-fold malathion resistance were 1/8, 1/12 and 1/6 of those in the corresponding susceptible strains, respectively. These results indicated that the insecticidal activity of fenvalerate against the two planthoppers and leafhopper was negatively correlated with the degree of the malathion resistance development. The same phenomenon was not found in the housefly.

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Insecticidal activity of mixtures of pyrethroids and organophosphates or carbamates was examined using the organophosphate and carbamate-resistant (Rop-c) strain of the green rice leafhopper. When mixtures of fenvalerate plus malathion, diazinon or MPMC and phenothrin plus MTMC or BPMC were applied topically to the adult females of the Rop-c strain, the toxicity was much higher than that of organophosphates and carbamates alone, but somewhat less toxic than fenvalerate and phenothrin alone. A remarkable synergism was exhibited by mixtures of fenvalerate plus malathion in the ratios of 1.0:1.5, 1:1 and 1.5:1.0 and those of fenvalerate plus diazinon in the ratios of 1.5:1.0 and 3:1. Mixtures of fenvalerate plus MPMC also showed synergism in the ratios of 1:3 and 3:1. Toxicity of mixtures of phenothrin and MTMC or BPMC decreased in accordance with the increased ratio of carbamates to phenothrin. However, synergism was shown by mixtures combined in higher ratios of carbamates to phenothrin. Fenpropathrin and permethrin also exhibited synergism against the Rop-c strain when they were combined with malathion or MTMC at the ratio of 1:1. Dust formulations of fenvalerate plus malathion or MTMC mixtures at a ratio ranging from 1:1 to 1:5 were found to have remarkably higher insecticidal activity compared to MTMC alone. Mixtures of fenvalerate and malathion or MTMC showed synergism when applied as dust formulation at a ratio of 1:5.

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Strains of the rice brown planthopper and small brown planthopper with 360 -and 370-fold resistance to malathion were respectively and successively selected with fenvalerate to trace the changes of LD₅₀ values of malathion and fenvalerate. The LD₅₀ value of malathion markedly decreased during the first five to six generations of selection in both planthoppers, but little changed by further selection (equilibrated state). In both planthoppers, the LD₅₀ value of malathion in the final (19th) generation of selection was about 1/4 that of the parent strains. In the fenvalerate-selected strain of the rice brown planthopper, the LD₅₀ values of fenitrothion, diazinon and phenthoate decreased to 1/2 to 1/5 during the selection of the first seven generations. In the fenvalerate-selected strain of the small brown planthopper, on the other hand, decreases in the LD₅₀ value of these insecticides were minimal. The LD₅₀ value of fenvalerate increased in the fenvalerate-selected strains of the two planthoppers. This increase, however, did not proceed in proportion to the change in the level of resistance to malathion; the LD₅₀ value did not markedly increase before the level of resistance to malathion reached an equilibrium. In the final (19th) generation of selection, the LD₅₀ value of fenvalerate was about 11-times as high as those in the corresponding parent strains in the rice brown planthopper, and about 5-times in the small brown planthopper.

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Uptake, translocation and metabolic fate of ¹⁴C-molinate (S-ethylperhydro-2-¹⁴C-azepin-1-carbothioate) in rice plants and barnyardgrass were studied in the laboratory. Molinate was absorbed through the roots and the basal parts of the shoots by both plants. Greater amounts of molinate were absorbed by barnyardgrass than by rice plants in every case. Although the radioactivity was translocated into whole plants when ¹⁴C-molinate was absorbed through the roots by both plants, the radioactivity moved only acropetally in rice plants and both acropetally and basepetally in barnyardgrass when ¹⁴C-molinate was absorbed through the basal parts of the shoots. Organo-extractable metabolites, molinate sulfoxide, azepine ring-4-OH-, -2-oxo-, and -4-oxo- derivatives, S-β-hydroxyethyl derivative, hexamethyleneimine (HMI), 4-OH-HMI, 2-oxo-HMI, S-carboxymethyl derivative, and S-ethyl-N-carboxymethyl thiocarbamate were identified by TLC. The compounds other than sulfoxide and 2 kinds of oxo-derivatives were also found in conjugated forms. Degradation of molinate was more rapid in barnyardgrass than in rice plants. Although molinate was degraded predominantly through the same pathways in barnyardgrass as in rice plants, there were greater amounts of conjugates derived from the basic metabolites, presumably imine compounds, in barnyardgrass, while most of the conjugates were derived from acidic and/or neutral metabolites in rice plants. Most portion of these conjugates was found to be glucosides in rice plants, but a few in barnyardgrass. Possible mechanisms of the herbicidal selectivity between rice plants and barnyardgrass were attributed to the difference in the metabolic products and in the direction of translocation of molinate between both plants.

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Juveniles of Caenorhabditis elegans were transformed to dumpy in the media containing methomyl (10μg/ml) or aldoxycarb (500μg/ml), but not in the media containing methylisothiocyanate (MITC). The dumpy did not recover to its normal structure even after being transferred to fresh medium, but underwent to adulthood with a lower reproduction rate. The progeny from the dumpy forms was normal in structure, however, its reproductivity was as low as one-third of normal ones. Longevity of the dumpy form and its progeny were longer than those of normal worms. Methomyl (1μg/ml), MITC (1μg/ml) and aldoxycarb (10μg/ml) did not suppress population growth, but MITC (10μg/ml) did for the first two weeks. The population growth was markedly suppressed at 100μg/ml of methomyl, 20μg/ml of MITC and 1000μg/ml of aldoxycarb.

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An emulsifiable concentrate of carbaryl was developed and its efficacy improved by synergization with isobornyl thiocyanoacetate. The formulations exhibited satisfactory physico-chemical characteristics. Emulsions (up to 0.2% carbaryl) from these concentrates exhibited no phytotoxicity against Vicia faba, Daucus carrota, Brassica oleracea, Gossypium hirsutum, Rabhanus sativus, Brassica juncea and Lycopersicum esculentum. The synergized concentrate, however, showed phytotoxicity against Solanum tuberosum and Hibiscus esculentus. Isobornyl thiocyanoacetate showed a factor of synergism of 2.5 at the 1:1 synergized concentrate. For a comparable bioefficacy with the commercial WDP, only 1/3 to 1/5 of carbaryl from these concentrates was required. Their 0.05% emulsions controlled the bollworm complex in cotton, increased seed cotton yield and left no detectable residues in lint and seed at harvest. In insect control and yield increase, the 0.05% emulsions from the synergized EC matched 0.2% carbaryl from WDP and 0.02% fenvalerate emulsions. Carbaryl WDP and fenvalerate, however, left detectable residues at harvest.

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Debrominated derivative of bromobutide labeled at carbonyl carbon ([carbonyl-¹⁴C] N-(1-methyl-1-phenylethyl)-3, 3-dimethylbutanamide, ¹⁴CO-deBr-bromobutide) was orally administered to seven-week old male S. D. rats and ICR mice and the fates of the compound were investigated to compare with those of bromobutide. In rats, deBr-bromobutide was rapidly hydroxylated at phenyl and t-butyl groups, and excreted quantitatively. ¹⁴CO-deBr-Bromobutide treatments gave faster ¹⁴C elimination, higher urinary excretion, and lower ¹⁴C residue levels in tissues and contents of intestinal tract compared with ¹⁴CO-bromobutide administration. deBr-Bromobutide was a better substrate for ω-hydroxylation than bromobutide in a microsomal suspension of rat liver with NADPH, but was a poor substrate for aromatic hydroxylation as bromobutide in in vitro assay. Major metabolites of deBr-bromobutide and bromobutide in rats were glucuronides of the alcohol and phenol derivatives and underwent enterohepatic circulation. Glucuronides of alcohol derivatives (major products) from deBr-bromobutide exhibited faster urinary excretion after conversion to carboxylic acids, while phenol type glucuronides (major metabolites) from bromobutide was retained slightly longer in the body. Mice had higher activities of hydroxylation, especially at the phenyl group and threshold value of higher molecular weight for biliary excretion than rats so as to give faster metabolism and higher urinary excretion for both compounds. It was concluded that although there were some species differences and substrate specificities for enzymatic hydroxylation, deBr-bromobutide behaved in quite a similar way as bromobutide did and that the metabolic pathway established for deBr-bromobutide from the identification of metabolites was, in turn, involved in the identification of bromobutide in mammals.

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Metabolism of 2, 3-, 2, 4-, 2, 5-, 2, 6-, 3, 4- and 3, 5-dichloro-1-nitrobenzenes by Mucor javanicus and metabolites of 2, 4-dichloro-1-nitrobenzene (2, 4-DCNB) by seven fungi were investigated. The dichloronitrobenzenes were reduced predominantly to the corresponding benzenamines by M. Javanicus. In addition to the benzenamine derivatives, minor metabolites in which an ortho-chlorine atom was substituted with a methylthio group were detected in the medium of M. javanicus administered 2, 3- and 2, 4-DCNB. More or less amounts of 2, 4-dichlorobenzenamine and 4-chloro-2-methylthio-1-nitrobenzene were detected as metabolites of 2, 4-DCNB also in the media of M. griseo-cyanus, M. hiemalis, M. praini and Aspergillus flavus.

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By applying differential saturation EAG (DS-EAG) technique, the olfactory receptor for germacrene-D (1), a sex pheromone mimic of the American cockroach, was investigated using natural sex pheromones [periplanone-A (2) and periplanone-B (3)], a general odor (camphor) and this mimic. The mimic was consequently revealed to be involved in the sex pheromone receptor responsible for periplanone-A in preference to that for periplanone-B.

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Translocation and metabolism of a systemic fungicide procymidone [Sumilex^®, N-(3, 5-dichlorophenyl)-1, 2-dimethylcyclopropane-1, 2-dicarboximide] radiolabeled at the carbonyl carbon were examined in cucumber and bean plants under laboratory conditions. The fungicide disappeared from the plants with a half-life of 20 days, after foliar application at a rate of 250μg per leaf. Procymidone was metabolized in plants via hydroxylation at the methyl group or the 4-position of phenyl group, or hydrolysis at the cyclic imide linkage. Very little of radioactivity translocated to other parts of the plants including edible portions. When the fungicide was applied to the surface of a cucumber fruit, approximately 24% of the applied radioactivity penetrated into the fruit in a day. However, there was no significant increase of radioactivity in the fruit thereafter. When bean plant seedlings were cultivated for 42 days in Kodaira light clay and Takarazuka loamy sand soils treated with 10ppm of ¹⁴C-procymidone, shoots, and pods and seeds contained 12.3-15.3ppm and 0.42-0.66ppm of ¹⁴C, respectively. Preincubation of procymidone treated soils for up to 5 months significantly lowered ¹⁴C residues taken up in plants, especially in shoots and pods and seeds.

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Prothiophos oxon (S-propyl form) and its S-methyl, ethyl and butyl homologs were poor in vitro inhibitors of acetylcholinesterase (AChE), but the S-propyl and butyl oxons were highly insecticidal to houseflies, and inhibited ACNE in vivo. Evidence indicates that such S-alkyl oxons are converted to unstable intermediates by mixed function oxidase system, which have been oxidized on the sulfur and are more reactive with AChE in the case of the S-propyl and butyl oxons, when more hydrolyzable in the case of the S-methyl and ethyl oxons.

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The electrode was inserted in the hypopharynx of the tobacco cutworm larva and the antifeeding compounds were topically applied at the various mouth parts by means of the microsyringe. The larval hypopharyn and maxillary palps were the most sensitive targets to chlordimeform and clerodin, respectively. The results led to the conclusion that the proposed primary sites of action of clerodin are the maxillary palps. On the other hand, primary site of action of chlordimeform is the hypopharynx.

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Solid pesticide carriers have been found to influence isomalathion formation in malathion powders. Of the carriers tested, formulations with only hydrated calcium silicate and silica gel-H complied with the AID/WHO requirement for isomalathion content. No relationship between isomalathion formation and physico-chemical characteristics of the carriers or period after incubation could be observed.

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The malathion- and fenitrothion-resistant (Rm and Rf) strains of the rice brown planthopper were established by successive selection with malathion and fenitrothion, respectively. The Rm strain selected with malathion for 42 generations developed 93-fold resistance to malathion, and the Rf strain selected with fenitrothion for 39 generations developed 289-fold resistance to fenitrothion. The Rm strain showed 5- to 26-fold cross resistance to naled, tetrachlorvinphos, monocrotophos, propaphos, fenthion, fenitrothion, diazinon, isoxathion, pyridaphenthion, disulfoton, dimethoate, phenthoate, mecarbam, carbaryl, propoxur, XMC and methomyl. The Rf strain showed high resistance to fenthion (271-fold), diazinon (71-fold), isoxathion (270-fold), pyridaphenthion (412-fold), EPN (177-fold), malathion (421-fold) and phenthoate (157-fold), and also showed 5- to 32-fold cross resistance to naled, dimethylvinphos, tetrachlorvinphos, monocrotophos, propaphos, disulfoton, dimethoate, mecarbam, carbaryl, MPMC, BPMC, propoxur, XMC and methomyl. In both Rm and Rf strains, no cross resistance to trichlorfon, pyrethrins and organophosphorus fungicides such as IBP and edifenphos were found.

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Insecticidal activities of pyrethroids were evaluated in terms of topical toxicities against a susceptible (S) strain and a Rop-c strain having multiple resistance to organophosphates and carbamates. Against the S strain, pyrethroids showed comparable or higher insecticidal activities than conventionally used malathion, carbaryl or MTMC. Pyrethrins and fenpropathrin were highly effective. LD₅₀ values of tetramethrin, permethrin and fenpropathrin in the Rop-c strain were somewhat higher than those in the S strain, but the insecticidal activities of pyrethrins, allethrin and resmethrin against the Rop-c strain were comparable to those against the S strain. Fenvalerate was 4.3 times more effective to the Rop-c strain than to the S strain.

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