This paper reports the synthesis of novel N-alkyl-N-(substituted benzyl)-4-halo-2-alkenamides and their herbicidal activity against Echinochloa oryzicola. Their herbicidal activity was observed to be light-dependent. The study on the structure-activity relationships revealed that 4-chloro-2-pentenoyl is the best as the acyl skeleton, and the combinations of either isobutyl or isopentyl and either 4-cyano- or 4-chlorobenzyl substituents on the amide nitrogen atom are the most favorable to the activity.

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The herbicidal activity of N-alkyl-N-(4-substituted benzyl)-4-chloro-2-pentenamides against a barnyard grass species, Echinochloa oryzicola, was evaluated, and the potency variations were quantitatively analyzed using physicochemical parameters for the N-alkyl and the benzyl-benzene ring substituents in the amide moiety. The results indicated that the herbicidal potency was parabolically related with the total hydrophobicity of the amide moiety. The electron-withdrawing property of the benzene-ring substituents as well as their hydrogen-bonding accepting ability was significant in potentiating the herbicidal activity.

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Tobacco cell lines resistant to photobleaching herbicides were selected by subculturing tobacco calli regenerated from protoplasts in the presence of ET-62311 (4-chloro-3-[2, 4-dichloro-5-(2-propenyloxy)phenyl]-5-difluoromethoxy-1-methylpyrazole), a derivative of pyraflufen-ethyl [ethyl 2-chloro-5-(4-chloro-5-difluoromethoxy-1-methylpyrazol-3-yl)-4-fluorophenoxyacetate] (formerly known as ET-751). Selected cell lines were more than 240-fold resistant than normal cells and designated as ETR-056, 245 and 253. The ET-62311 treatment induced Proto IX accumulation in ETR-056, but not in ETR-245 nor 253. Cross-resistance of resistant cell lines to herbicides with various mode of action was evaluated. Each resistant cell line was cross-resistant to photobleaching herbicides such as pyraflufen-ethyl. In addition, ETR-056 was cross-resistant to paraquat and ETR-253 was cross-resistant to several herbicides with different modes of action. On the other hand, protoporphyrinogen oxidase (Protox) activity in ETR-245 was almost equivalent to that in normal cells, but more than 100-fold resistant to pyraflufen-ethyl. These results suggested the involvement of radical scavenger in ETR-056, multiple resistance due to a reduced uptake and/or an enhanced metabolism of the herbicides in ETR-253 and an alteration of Protox from photobleaching herbicide sensitive form to resistant one in ETR-245.

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The resistant mechanism of the tobacco cell line ETR-245 to the photobleaching herbicide, pyraflufen-ethyl, was analyzed at the molecular level. Wild-type cDNAs of protoporphyrinogen oxidase (Protox), the target enzyme of photobleaching herbicides, were isolated from tobacco leaves and sequenced by the genetic complementation. Using the sequence information, Protox cDNAs were amplified by RT-PCR from normal and ETR-245 cells. The sensitivities of each Protox gene product to pyraflufen-ethyl were compared. Although mitochondrial Protox gene products showed almost equivalent sensitivities to pyraflufen-ethyl, the chloroplastic Protox gene product encoded by the cDNA from ETR-245 cells was more than 4000-fold resistant than that encoded by the cDNA from normal cells. The nucleotide sequence analysis of these chloroplastic Protox cDNAs revealed single-point mutation in the Protox cDNA from ETR-245, which accompanied with one amino acid substitution. From these results, it was clarified that this mutation was the cause for the resistance in ETR-245.

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In the previous report, it was reported that the controlled-release formulation of acetamiprid exhibited excellent efficacy in planting hole application and nursery box application against the diamondback moth on cabbage. For the purpose of finding out the more practical, effective usage in soil application for acetamiprid 2% granule, various treating methods were investigated. As a result of the trials, it was confirmed that the order of efficacy was as followed: planting hole application 1g/plant≈nursery box application 1g/plant>plant foot application 1g/plant, and planting hole application 1g/plant≈row application 6kg/10 a≈overall-ridge application 12kg/10a. In the planting hole application, there was no difference in the efficacy between the leaf stages of seedlings as far as the comparison between 2- and 4-leaf stage, and little difference in the efficacy of planting hole application between cell-raised seedlings and bare-root ones used.

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Protoporphyrinogen-IX oxidase inhibition and peroxidizing phytotoxicity were determined using a series of fluorinated and non-fluorinated alkyl 2-chloro-5-(3, 4, 5, 6-tetrahydrophthalimido)benzoates and their parent benzoic acid derivatives. Protoporphyrinogen-IX oxidase from corn etioplasts was extracted, and ethane formation by intact cells of the green algae Scenedesmus acutus was measured. The benzoates with a fluorine atom exhibited stronger peroxidizing phytotoxicity (higher ethane formation) than the benzoates having no fluorine atom although protoporphyrinogen-IX oxidase inhibition by the fluorinated analogues was found to be weaker or almost equal to the non-fluorinated analogues. These data strengthen and generalize our previous findings with cyclic imides having an N-(4-chloro-2-fluoro-5-carboxyphenyl) group. The fluorinated analogues, which are not necessarily stronger protoporphyrinogen-IX oxidase inhibitors, exhibit stronger peroxidizing phytotoxicity with intact plant cells than those without a fluorine atom.

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New types of acaricides containing pyrazolecarboxamide as a core structure were synthesized and their acaricidal potency and fish toxicity were examined. N-Phenoxyethylpyrazole-5-carboxamide derivatives (III) showed remarkably a high activity against two-spotted spider mite and severe toxicity against fish such as medaka. On the other hand, among N-acyl-N-phenoxyethylpyrazole-5-carboxamide derivatives (IV) which were designed to get the selective activity between mite and fish, the only series of compounds having tert-butyl group at 3-position and hydrogen atom at 4-position on the pyrazole ring showed much less toxicity against medaka with higher activity against mites than the corresponding unacylated compounds. Their structure-activity relationships are discussed in this paper.

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A new method of molecular similarity analysis was applied to the three-dimensional quantitative structure-activity relationship (3D-QSAR) of neonicotinoid insecticides such as imidacloprid and acetamiprid. Two novel indices of molecular similarity were defined as inner products of vectors representing electrostatic and steric properties of molecules in three-dimensional space, respectively. The similarity indices of 12 neonicotinoids having various structures were calculated for each pair of the molecules, and a similarity matrix of the indices was generated. The partial least squares (PLS) method was employed to analyze the correlation between the receptor-binding activity and the similarity indices. A significant QSAR model was obtained on the basis of similarity and dissimilarity of the whole series of compounds, indicating that both the similarities in steric and electrostatic properties are important for the activity. The structural requirements of the molecules for the activity were visually presented by displaying the three-dimensional grid points which contribute significantly to the activity in terms of steric and electrostatic properties.

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The supernatants of Serratia marcescens culture was shown to possess an enhancing effect on the larvicidal activity of Bacillus thuringiensis delta-endotoxin (Cry1C) against the common cutworm, Spodoptera litura. The synergistic effect was observed in both larval mortality and growth inhibition. The synergistic activity increased in proportion to the increment either of the supernatant or Cry1C concentration. The addition of supernatants of S. marcescens culture to Cry1C was able to enhance the insecticidal activity of delta-endotoxin over 8 fold compared with that of toxin alone. The synergism was very high to the insecticidal activity against S. litura but not in other three lepidopterous insects tested, i. e., Mamestra brassicae, Plutella xylostella and Adoxophyes honmai. Therefore the synergistic activity of the supernatants of S. marcescens culture seemed to be specific to insect species.

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[in Japanese]

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The effect of the variation of climatic input parameters on the leaching of pesticides is presented in this study. Based on weather series with daily precipitation and temperature data over a period of 30 years for a total of 13 regions in Germany Monte-Carlo simulations using the computer model PELMO have been performed for spring as well as for autumn applications. The results show that independent on the region the fluctuations always decreased with increasing leaching potential. The geometric standard deviation for pesticide concentrations of 1.0μg/l was in the range of 1.6 to 2.4. However, simulations with an example pesticide demonstrated that the differences between different regions were of higher importance than differences due to variance of climate within a given region. It was concluded that the next generation of our information infrastructures needs to take into account the spatial component of input data.

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A computer software (to be registered as InPest) was developed in order to make a risk assessment of indoor-use insecticides to both applicators and indoor occupants in various applications including space spraying, electric vaporizing, broadcast spraying and residual spraying. The movement of an insecticide in a sprayed room was described as precisely as possible by utilizing various physicochemical equations, which were incorporated in the Fugacity model (Level IV). When insecticide information regarding molecular weight, vapor pressure, water solubility and octanol/water partition coefficient is available, InPest is able to simulate the time-dependent concentrations of the insecticide in the air and residual amounts on floor, wall and ceiling compartments under various conditions. Simulation data indicate that the predicted behavior of the insecticide fully agrees with the measured one. Based on the predicted concentrations, the levels of exposure to applicators and room occupants via inhalation, dermal or oral intake can be computed and compared with the mammalian toxicological data. Thus, InPest is a powerful tool for evaluating the safety of indoor-use insecticides with regard to human health.

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Degradation by sunlight is an important route of dissipation for pesticides applied to rice paddies. The clear and shallow water filters very little of the incident light and allows both direct and indirect photochemical processes to occur within the water column and at the sediment-water interface. Of the indirect processes, degradation by hydroxyl and carbonate radical and singlet oxygen have been shown to be important for selective classes of pesticide chemistry. The ability of pesticides to undergo direct photolysis can be easily evaluated by available protocols conducted by pesticide registrants, while the reactivity of pesticides to radical oxidants are best evaluated by competition kinetic methods. Rate constants for pesticides obtained by these methods can be incorporated into the computer exposure model EXAMS2 to compare the importance of the photochemical processes to other dissipation pathways occurring simultaneously in the rice paddy ecosystem.

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[in Japanese]

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[in Japanese]

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