Pyriproxyfen is a broad-spectrum insect growth regulator (IGR) with insecticidal activity against public health insect pests such as houseflies, mosquitoes and cockroaches. In agriculture and horticulture, pyriproxyfen has registered uses for the control of scale, whitefly, aphids and fire ants. It is used extensively worldwide, particularly in developing countries, although it has no significant uses in California. Pyriproxyfen acts on the endocrine system of insects by mimicking the juvenile hormone, thereby hindering molting and subsequently inhibiting reproduction. IGRs are unique in that they are specific for insects and have very low mammalian toxicity. As such, pyriproxyfen has received U.S. EPA status as a Reduced Risk insecticide and an organophosphate alternative and is the only pesticide approved by the World Health Organization (WHO) for treatment of potable water against mosquito. However, concerns about its environmental persistence and latent toxicity to nontarget organisms have been recently raised and discussed. In this context, a detailed review of the environmental fate and physicochemical properties of pyriproxyfen from the available scientific literature and from data gathered in its development and testing is needed. This paper gathers, combines, and abridges important environmental fate and property data on pyriproxyfen for academics, environmental scientists and agricultural professionals needing ready access to this information.

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In this study, nine strains of Aedes aegypti mosquitoes from different localities in Thailand were subjected to susceptibility tests against commonly used insecticides for vector control in Thailand. Aedes aegypti from different localities were strongly resistant to DDT and permethrin, except for one strain from Chiang Mai (Chiang Mai-P) that was found to be susceptible to permethrin. In contrast, most Ae. aegypti strains are susceptible to deltamethrin and alphacypermethrin, except that Bangkok and Nonthaburi strains showed incipient resistance to deltamethrin and alphacypermethrin, respectively. Various levels of malathion and propoxur susceptibility were also detected in Ae. aegypti strains; however, two strains of Ae. aegypti (Satun and Nonthaburi) were found to be completely susceptible to malathion. The insecticide susceptibility level in three strains of Culex quinquefasciatus was also investigated. The results indicated strong resistance to DDT and moderate resistance to permethrin. Two strains from Bangkok and Nonthaburi were found to be completely susceptible to malathion and propoxur. One strain from Pathum Thani showed incipient resistance to both compounds. We conclude that deltamethrin and alphacypermethrin are still effective insecticides for the dengue control program and malathion and propoxur may be alternative insecticides to control Cx. quinquefasciatus.

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Derivatives of 2,4-dioxo-5-benzylidene-3-thiazolidineacetamide were prepared and the fungicidal and the bactericidal activities of twenty-three related compounds were examined. In vitro tests at a concentration of 10 mg/l, some derivatives showed moderate or considerable inhibition against Pyricularia oryzae (P. oryzae), Rhizoctonia solani (R. solani), and Septoria tritici, but only modest activity against Botrytis cinerea and Burkhorderia gluma. The activity of a few compounds was enhanced by co-application of salicyl hydroxymate (SHAM), which is known to potentiate the fungicidal activity of strobilurins. In pot tests at a concentration of 500 mg/l, some compounds showed appreciable activity against rice blast, late blight on tomatoes, downy mildew on cucumbers, or leaf rust on wheat. Of these compounds N,N-dimethyl-2,4-dioxo-5-benzyl-3-thiazolidineacetamide completely removed the downy mildew. Most of them showed only modest activity against gray mold on cucumbers.

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The herbicidal activity and properties of a novel paddy herbicide, benzobicyclon [3-(2-chloro-4-mesylbenzoyl)-2-phenylthiobicyclo[3.2.1]oct-2-en-4-one], were examined under flooded conditions. Benzobicyclon showed broad-spectrum activity at doses of 200–300 g a.i./ha when applied from pre-emergence to early post-emergence against annual grass, sedge, and broadleaf weeds in paddy. Benzobicyclon has excellent selectivity of transplanted rice. The most significant herbicidal symptom was bleaching. Benzobicyclon had a wide application window and controlled Scirpus juncoides up to 5 leaf stages, which is difficult to control throughout the season using other paddy herbicides. Benzobicyclon controlled S. juncoides much faster under high temperature (25°C) than under low temperature (15°C); however, the herbicidal efficacy was almost the same, regardless of the temperature, when the leaf stage of the untreated control was the same. The residual activity of benzobicyclon on S. juncoides lasted for at least 8 weeks. The herbicidal activity of benzobicyclon at doses of 200–300 g a.i./ha was not affected by the emergence depth (0–3 cm) of S. juncoides or soil types (clay loam, loam, light clay, sandy loam, and heavy clay). Moreover, benzobicyclon controlled sulfonylurea herbicide-resistant biotypes as well as wild-type weeds.

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This work describes the design, synthesis, AChE inhibitory activity, and structure-activity relationship of compounds related to a recently discovered series of AChE inhibitors: phthalimide alkyloxyphenyl N-methylcarbamates. The influence of structural variations on inhibitory potency was carefully investigated by modifying different alkyloxy chain lengths and positions between phthalimide and phenyl N-methylcarbamate. The biological properties of the series were investigated in some detail by considering their activity on isolated enzymes. All of the newly synthesized derivatives, when tested on isolated AChE from the brain of the housefly (Musca domestica), were more active than phenyl N-methylcarbamate. In particular, compound I1 displayed the best AChE inhibition (352-fold higher than phenyl N-methylcarbamate, and 29-fold higher than metolcarb), which suggested that the phthalimide group of I1 bound strongly to the residues lining the gorge, and phenyl N-methylcarbamate bound at the catalytic sites.

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Imazamethabenz is used for postemergence control of wild oats and other weeds in wheat, barley, and sunflower. Imazamethabenz hydrolysis and the formation of the acid form, imazamethabenz acid, are necessary for herbicidal activity. The type of imazamethabenz acid adsorption on oxides affects its fate for herbicidal activity and persistence. Imazamethabenz hydrolysis with or without oxides and imazamethabenz acid adsorption to oxides were examined in aqueous buffer suspensions of aluminum oxide (Al₂O₃), goethite (FeOOH), amorphous silica (SiO₂), and anatase (TiO₂) at several pH. Imazamethabenz hydrolysis rates in oxide-free solution followed first-order kinetics. Hydrolysis rate increased as pH increased, and exhibited a log-linear relationship with pH. Hydrolysis of imazamethabenz in oxide solutions also followed first-order kinetics. Some oxides increased the imazamethabenz hydrolysis rate at a given pH, but pH played a much greater role in increasing the hydrolysis rate of imazamethabenz than did oxides. Adsorption to oxides of imazamethabenz acid formed from imazamethabenz hydrolysis decreased as pH increased. At pH 5.0, acid adsorption to Al₂O₃ was 44% of the total acid product, while acid adsorption to Al₂O₃ was 6% of the total acid product at pH 8.0.

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A series of ethyl 4-(2-benzylalkyloxy)benzoates possessing precocious metamorphosis-inducing activity showed juvenile hormone (JH) activity when topically applied to allatectomized 4th instar larvae of Bombyx mori. Hexyl (KF-13) and heptyl analogs, which induced precocious metamorphosis at low doses, had relatively high JH activity. In both compounds, (S)-enantiomers were more active than (R)-enantiomers. A correlation was observed between JH activity and anti-JH activity in the ethyl 4-(2-benzylalkyloxy)benzoate series. Replacement of the 4-ethoxycarbonyl group with a 4-ethyl or 3,4-methylenedioxy group in KF-13 eliminated both JH and anti-JH activity. © Pesticide Science Society of Japan

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A simple, rapid method to determine residues of chlorothalonil in green tea leaves was developed using a commercial chlorothalonil kit based on ELISA. Chlorothalonil in green tea leaves was measured using the chlorothalonil kit after being extracted by methanol or boiling in water and diluted with 10% methanol. Because the extracts of green tea leaves caused significant interference in the assay, a refinement method was examined. One ml of the extract from green tea leaves boiled in water or extracted with methanol was added to Oasis HLB (60 mg) and purified with 2ml of 80% methanol. After that, chlorothalonil on the HLB was extracted with 2 ml of 100% methanol. It was suggested from the experiment that the component that was removed by column refinement was catechin, being the cause of interference with the chlorothalonil kit. As the results, average recoveries from the chlorothalonil-spiked green tea leaves were 86–113%, and the coefficients of variation were below 10% in most cases. The coefficient of correlation between the ELISA and GC/MS methods was 0.99. Analysis equivalent to GC became possible using ELISA, and we revealed that catechin is the main factor interfering with ELISA analysis, and established a refining process. It was confirmed that the methanol treatment method for HLB was useful for the rapid analysis of chlorothalonil residues in green tea leaves.

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We conducted a probabilistic ecological risk assessment of the herbicide simetryn which is used in Japanese paddy fields. The EC₅₀ values for 31 algal genera were fitted to log-normal distribution, and the hazardous concentration for 5% of algal genera (HC₅) was estimated to be 8.2 μg/l. The predicted environmental concentration (PEC) of simetryn was calculated to be 0.71 μg/l using an environmental model and the standard scenario defined by the Ministry of Environment, Japan. The distribution of PEC was quantified using Monte Carlo analysis, and the mean of PEC was 0.77 μg/l and the 95 percentile was 2.8 μg/l. The joint probability curve was derived by comparing the species sensitivity distribution and the distribution of PECs, and the probability of exceeding HC₅ was estimated to be 1.5%.

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