Millions of cases of pesticide intoxication occur yearly and represent a public health problem. In addition, pesticide poisoning is the preferred suicidal method in rural areas. The use of enzymes for the treatment of intoxication due to organophosphorus pesticides was proposed decades ago. Several enzymes are able to transform organophosphorus compounds such as pesticides and nerve agents. Some specific enzymatic treatments have been proposed, including direct enzyme injection, liposome and erythrocytes carriers, PEGylated preparations and extracorporeal enzymatic treatments. Nevertheless, no enzymatic treatments are currently available. In this work, the use of enzymes for treating of organophosphorus pesticide intoxication is critically reviewed and the remaining challenges are discussed.

This study aimed to describe the relationship between viral infection in Nilaparvata lugens (Stål), the brown planthopper (BPH), and different insecticide susceptibilities. BPH-resistant strains were selected using fenthion (an organophosphate) or etofenprox (a pyrethroid); a susceptible strain was used as the baseline colony before insecticide selection. All strains were infected with rice ragged stunt virus (RRSV) or rice grassy stunt virus (RGSV), after which the activities of three detoxification enzymes, cytochrome-P450-monooxygenase (P450), glutathione S-transferase (GST), and carboxylesterase (CE), were compared. Males of the strains selected for both insecticides showed high P450 and GST-CDNB activities. The activity of all enzymes was higher in males than in females, as a whole. However, males of the susceptible strain infected with RRSV showed decreased CE and GST-CDNB activities. BPH with low susceptibility to etofenprox showed a marked increase in P450 activity after RRSV infection; the GST-CDNB activity of females in the insecticide-resistant strain increased. RGSV infection induced high CE and P450 activities in etofenprox-selected females. The RRSV infection rate, but not the RGSV, decreased in etofenprox-selected strains.

The monitoring of pesticide concentrations in Japanese rivers was conducted via a grab sampling method and a passive sampling method using the polar organic chemical integrated sampler (POCIS). The results showed that cumulative detections were 84 with grab sampling and 98 with the POCIS. All of the pesticides detected by grab sampling could be quantified with a POCIS except for one (although its traces were detected). In addition, 15 detections quantified by POCIS were undetected by grab sampling. The average concentrations of pesticides detected by both the POCIS and grab sampling during the investigation period were compared. A good correlation was observed between the two methods with a slope of 1.00 and a coefficient of correlation (r) of 0.897 (n=79). Although high temporal variability was observed in the pesticide concentrations by grab sampling, the average pesticide concentrations obtained by the two methods showed similar values during the investigation period.

The transport of three herbicides, pyriminobac-methyl, imazosulfuron and pyraclonil from a watershed that includes 40 ha of paddy fields to a drainage canal was monitored in the Lake Biwa basin, Japan. Based on the intensive monitoring of all paddy plots and in the drainage canal conducted on 3 days during and after the application period, the passage of herbicide discharge from the paddy fields to the drainage canal was separated into surface runoff obtained from field observations and percolation flow calculated from the herbicide mass balance. Surface runoff from paddy plots immediately after herbicide application, discharging a large volume of paddy water, or both processes in conjunction had a significant effect on herbicide discharge. Without surface runoff, paddy fields discharged a consistently high amount of herbicide gradually by percolation flow. These results suggest that considerable amounts of herbicides were discharged into the drainage canal through percolation even if appropriate water management to prevent herbicide surface runoff was practiced.

This study’s objective was to evaluate the contributions of benomyl and a melanin biosynthesis dehydratase inhibitor (MBI-D) mixture to preventing the re-emergence of MBI-D-resistant Pyricularia oryzae in rice fields. In nursery boxes, applications of diclocymet or mixtures of diclocymet and tiadinil showed low leaf blast incidences, but MBI-D-resistant isolates were re-selected. However, a management program applying both benomyl and MBI-D-related products to nursery box plants prevented the re-emergence of MBI-D-resistant isolates more effectively than the application of only MBI-D-related products.

Experimentally applying pesticides is an important method to assess the efficacy of weed biocontrol agents, but potential direct effects of the chemicals on plant performance are controversial or unknown. We assessed how three broad-spectrum insecticides applied in combination affect the performance of the widely invasive, crop-yield reducing, allergenic common ragweed (Ambrosia artemisiifolia L.) in an insect-free environment. Spraying insecticides had no significant effects on aboveground dry weight, seed and pollen output or pollen allergenicity, and only explained 1–8% of variation in these parameters. Our insecticide treatment can hence be applied to assess biocontrol impact on biomass and reproductive output of common ragweed. As our insecticide treatment delayed senescence, however, other methods of insect exclusion should be preferred when studying common ragweed phenology.

Methyl parathion (MP) decontamination by hydrolysis in aqueous solutions containing 2-aminoethanol (EA) was investigated using the UV-Visible and GC/MS techniques. The kinetics of the hydrolysis reaction was studied at pH values of 4, 7, and 9 in water at 75, 85, and 95°C, respectively. At various EA concentrations 60, 100, and 200 mg/L MP degradation followed pseudo-first order kinetics and was found to be strongly pH and temperature dependent. The rate of MP degradation accelerated significantly as pH increased. The conversion reached 93.5% after 90 min of hydrolysis at a pH of 9, as compared to 69.9% and 49.8% at pH values of 7 and 4, respectively. The MP degradation byproducts removed from aqueous solutions by solid phase microextraction (SPME) were identified. The main intermediate products were p-nitrophenol and O,O-dimethyl phosphorothioate. This study concludes that hydrolysis in the presence of EA is an effective process for decontaminating solutions containing MP.

An interaction between two different living creatures is often mediated by a chemical substance, along with metabolic or morphological differentiation. Such phenomenon-based investigation of chemical substances sometimes leads to the discovery of a novel signaling substance associated with biological pest control, including pinpoint regulation of fundamental metabolisms. In studies on the metabolic regulation of denitrifying bacteria and phytopathogenic microorganisms, such chemicals linked to the introduction of new ideas and unique approaches for biorational pest controls are described.