Journal of Pesticide Science最新文献

Allelopathy is the interaction between donor plants and receiver plants through allelochemicals. According to a great number of publications, allelopathy may be involved in several ecological aspects such as the formation of monospecific stands and sparse understory vegetation for certain plant species. Allelopathy also contributes to the naturalization of invasive plant species in introduced ranges. Autotoxicity is a particular type of allelopathy involving certain compounds. Many medicinal plants have been reported to show relatively high allelopathic activity. We selected plant species that show high allelopathic activity and isolated allelochemicals through the bioassay-guided purification process. More than 100 allelochemicals, including novel compounds have been identified in some medicinal and invasive plants, plants forming monospecific stands, plants with sparse understory vegetation, and plants showing autotoxicity. The allelopathic activity of benzoxazinones and related compounds was also determined.

The objective of this study was to assess the long-term stability of pesticide residues in brown rice and soybean. The long-term stability of pesticide residues in brown rice and soybean was assessed for 5415 days (over 14 years) and 1801 days (about 5 years), respectively. The samples—certified reference materials (CRMs) 7504-a (brown rice) and 7509-a (soybean) —were prepared by freeze-pulverization. Two target pesticides (etofenprox and fenitrothion) were selected for brown rice and four (chlorpyrifos, diazinon, fenitrothion, and permethrin) for soybean. Our analytical results for long-term stability based on highly reliable isotope dilution mass spectrometry were in the range of expanded uncertainty (k=2) for the certified values of each CRM. The concentration showed a decreasing trend in none of the target pesticides when the samples were stored at temperatures between −20 °C and −30 °C, which indicated that the target pesticides were stable for the tested long terms.

From the 992 samples of culture extracts of microorganisms isolated from soil in Japan, we found that the extract of Streptomyces sp. no. 226 inhibited Orobanche minor seed germination without significantly affecting the seed germination of Trifolium pratense and the growth of Aspergillus oryzae and Escherichia coli. Using ESI-MS, ¹H-NMR, and ¹³C-NMR, we identified the active compound as cycloheximide. Cycloheximide had half-maximum inhibitory concentrations of 2.6 ng/mL for the inhibition of seed germination of O. minor and 2.5 µg/mL for that of the conidial germination of A. oryzae. Since cycloheximide is known to inhibit translation by interacting with ribosomal protein L28 (RPL28) in yeast, we investigated whether RPL protein of O. minor plays a critical role in the inhibition of O. minor seed germination. Our data suggested that O. minor RPL27A was not sensitive to cycloheximide by comparing it to the strain expressing S. cerevisiae RPL28. These findings suggest the presence of an unidentified mechanism by which cycloheximide hinders O. minor seed germination.

Use of agro-chemicals in forage crops is restricted due to the fear of direct toxicity to livestock and risk of pesticide residue accumulation in the food chain. Wheat and barley can be used as green fodder and silage, and herbicide residue estimation in green fodder and silage is important for ensuring the safety of dairy cattle. A field experiment was conducted for two years to study pendimethalin residues in the green fodder and silage of wheat and barley. In both cereal crops, pendimethalin (1.125 kg a.i./ha) was applied as pre-emergence along with an unsprayed control. Pendimethalin residues in fodder, silage, and soil were estimated using gas chromatography-tandem mass spectrometry (GC-MS/MS). At harvest, pendimethalin residues in fodder and silage of wheat and barley were below the limit of quantification (<0.01 mg/kg) during both crop seasons. Pendimethalin can be safely used for weed control in winter cereals grown for fodder and silage.

Unmanned aerial vehicle (UAV) sprayers have been widely used in agriculture. With the goals of using pesticides efficiently and reducing their dosage, we evaluated the effects of adding and not adding special adjuvants to UAV sprayers on droplet deposition and the control effect of leaf folder insects. The deposition quantity and coverage area of UAV sprayers with the Kao Adjuvant A-200® on rice leaves were better than those without the Kao Adjuvant A-200®. Regarding the control effect on rice leaf rollers, UAV sprayers with the Kao Adjuvant A-200® were also better, and they also met the pesticide residue limit for brown rice. Kao Adjuvant A-200® can improve the UAV sprayer's droplet deposition and pest control effect. When the pesticide dosage was reduced by 30%, UAV sprayers with Kao Adjuvant A-200® can achieve a good control effect, which is very helpful in reducing the pesticide dosage.

The Cucurbitaceae family accumulates hydrophobic organic pollutants in its aerial parts at high concentrations. Major latex-like proteins (MLPs) were identified in zucchini (Cucurbita pepo) as a transporting factor for hydrophobic organic pollutants. MLPs bind to hydrophobic organic pollutants in the roots, are secreted to xylem vessels as complexes, and are transported to the aerial parts. However, the suitable conditions for binding MLPs to hydrophobic organic pollutants remain elusive. In the present study, we show that MLPs bind to the hydrophobic organic pollutant pyrene with higher affinity under acidic conditions. Our results demonstrated that pH regulates the binding of MLPs to hydrophobic organic pollutants.

Brassinosteroids (BRs) are steroid hormones that regulate plant growth, development, and stress resistance. In this study, we evaluated the effect of agrochemicals on dark-induced hypocotyl elongation, which is regulated by BRs, to identify novel chemicals that regulate BR action. We found that the juvenile hormone agonist fenoxycarb inhibited dark-induced hypocotyl elongation in Arabidopsis. Treatment with the same class of juvenile hormone agonist, pyriproxyfen, did not affect hypocotyl elongation. Co-treatment with fenoxycarb and BR partly canceled the fenoxycarb-induced hypocotyl suppression. In addition, gene expression analysis revealed that fenoxycarb altered the BR-responsive gene expression. These results indicate that fenoxycarb is a BR action inhibitor.