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  1. Lee-Yin C, Ismaill BS, Salmijah S, Halimah M
    J Environ Biol, 2013 Sep;34(5):957-61.
    PMID: 24558812
    The influence of temperature, moisture and organic matter on the persistence of cyfluthrin was determined using three types of Malaysian soils, namely clay, clay loam and sandy clay loam obtained from a tomato farm in Cameron Highlands, Pahang. The persistence of cyfluthrin was observed in the laboratory at two temperature levels of 25 and 35 degreeC and field water capacity of 30 and 80%. Treated soil samples were incubated in a growth chamber for 1, 2, 3, 5, 7, 10, 14, 21 and 28 days. The results from the incubation studies showed that temperature and organic matter content significantly reduced the half-life (t1/2) values of cyfluthrin in the three soil types, but moisture content had very little effect. It was observed that cyfluthrin persisted longer at lower temperature and moisture content and higher organic matter content in all the three soil types. The present study demonstrated that under the tropical conditions of Malaysia, cyfluthrin dissipated rapidly in soils compared to its dissipation in soils of temperate regions, evidently due to high temperature.
    Matched MeSH terms: Pyrethrins/metabolism*
  2. Chai LK, Mohd-Tahir N, Bruun Hansen HC
    Pest Manag Sci, 2009 Feb;65(2):189-96.
    PMID: 18979521 DOI: 10.1002/ps.1667
    High amounts of insecticides are often used in intensive tropical vegetable production systems. Their persistence and residues in vegetables and soils need to be studied to ensure food safety and environmental stability. The dissipation of acephate, chlorpyrifos, cypermethrin and their metabolites was studied in green mustard [Brassica juncea (L.) Coss.] and soils. Two treatments, Impact 75 (acephate) and Agent 505 (cypermethrin plus chlorpyrifos), were applied 4 times at weekly intervals.
    Matched MeSH terms: Pyrethrins/metabolism
  3. Mohd Firdaus MA, Agatz A, Hodson ME, Al-Khazrajy OSA, Boxall ABA
    Environ Toxicol Chem, 2018 05;37(5):1420-1429.
    PMID: 29341233 DOI: 10.1002/etc.4094
    Nanopesticides are novel plant protection products offering numerous benefits. Because nanoparticles behave differently from dissolved chemicals, the environmental risks of these materials could differ from conventional pesticides. We used soil-earthworm systems to compare the fate and uptake of analytical-grade bifenthrin to that of bifenthrin in traditional and nanoencapsulated formulations. Apparent sorption coefficients for bifenthrin were up to 3.8 times lower in the nano treatments than in the non-nano treatments, whereas dissipation half-lives of the nano treatments were up to 2 times longer. Earthworms in the nano treatments accumulated approximately 50% more bifenthrin than those in the non-nano treatments. In the non-nano treatments, most of the accumulated material was found in the earthworm tissue, whereas in the nano treatments, the majority resided in the gut. Evaluation of toxicokinetic modeling approaches showed that models incorporating the release rate of bifenthrin from the nanocapsule and distribution within the earthworm provided the best estimations of uptake from the nano-formulations. Overall, our findings indicate that the risks of nanopesticides may be different from those of conventional formulations. The modeling presented provides a starting point for assessing risks of these materials but needs to be further developed to better consider the behavior of the nanoencapsulated pesticide within the gut system. Environ Toxicol Chem 2018;37:1420-1429. © 2018 SETAC.
    Matched MeSH terms: Pyrethrins/metabolism
  4. Mohamed ME, Pahirulzaman KA, Lazarus CM
    Mol Biotechnol, 2016 Mar;58(3):172-8.
    PMID: 26718544 DOI: 10.1007/s12033-015-9911-0
    Pyrethrins are natural insecticides, which accumulate to high concentrations in pyrethrum (Chrysanthemum cinerariaefolium) flowers. Synthetic pyrethroids are more stable, more efficacious and cheaper, but contemporary requirements for safe and environmentally friendly pesticides encourage a return to the use of natural pyrethrins, and this would be favoured by development of an efficient route to their production by microbial fermentation. The biosynthesis of pyrethrins involves ester linkage between an acid moiety (chrysanthemoyl or pyrethroyl, synthesised via the mevalonic acid pathway from glucose), and an alcohol (pyrethrolone). Pyrethrolone is generated from 3-oxo-2-(2'-pentenyl)-cyclopentane-1-octanoic acid, which originates from α-linolenic acid via the jasmonic acid biosynthetic cascade. The first four genes in this cascade, encoding lipoxygenase 2, allene-oxide synthase, allene-oxide cyclase 2 and 12-oxophytodienoic acid reductase 3, were amplified from an Arabidopsis thaliana cDNA library, cloned in a purpose-built fungal multigene expression vector and expressed in Aspergillus oryzae. HPLC-MS analysis of the transgenic fungus homogenate gave good evidence for the presence of 3-oxo-2-(2'-pentenyl)-cyclopentane-1-octanoic acid.
    Matched MeSH terms: Pyrethrins/metabolism*
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