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Journal of Nematology Dec 1993The degradation of fenamiphos, fenamiphos sulfoxide, and fenamiphos sulfone was determined in a greenhouse experiment using autoclaved and nonautoclaved soil from field...
The degradation of fenamiphos, fenamiphos sulfoxide, and fenamiphos sulfone was determined in a greenhouse experiment using autoclaved and nonautoclaved soil from field plots treated or not treated with fenamiphos. Fenamiphos degradation and formation of fenamiphos sulfoxide was faster in uonautoclaved soil than in autoclaved soil. In nonautoclaved soil, previous exposure to fenamiphos was associated with increased rate of degradation of fenamiphos snlfoxide. Fenamiphos total toxic residue degraded more rapidly in nonautoclaved soil previously exposed to fenamiphos than in nonautoclaved soil never exposed to fenamiphos. This accelerated degradation was due to more rapid degradation of fenamiphos sulfoxide and appears to be biologically mediated.
PubMed: 19279826
DOI: No ID Found -
Scientific Reports Feb 2022Aphelenchoides besseyi could cause great yield losses of rice and many economically important crops. Acetylcholinesterase (AChE) inhibitors were commonly used to manage...
Aphelenchoides besseyi could cause great yield losses of rice and many economically important crops. Acetylcholinesterase (AChE) inhibitors were commonly used to manage plant-parasitic nematodes. However, nematodes resistant to AChE inhibitors have been increasingly reported due to the extensive use of these chemicals. The current study was aimed to establish the correlation between fenamiphos (an AChE-inhibitor) sensitivities and acetylcholinesterase genes (ace) by analyzing two isolates of A. besseyi (designated Rl and HSF), which displayed differential sensitivities to fenamiphos. The concentrations of fenamiphos that led to the death of 50% (LD) of Rl and HSF were 572.2 ppm and 129.4 ppm, respectively. Three ace genes were cloned from A. besseyi and sequenced. Sequence searching and phylogenic analyses revealed that AChEs of R1 and HSF shared strong similarities with those of various vertebrate and invertebrate species. Molecular docking analysis indicated that AChEs-HSF had much higher affinities to fenamiphos than AChEs-R1. Quantitative reverse transcriptase-PCR analyses revealed that expression of three ace genes were downregulated in HSF but were upregulated in Rl after exposure to 100 ppm fenamiphos for 12 h. The results indicated that the expression of the ace genes was modulated in response to fenamiphos in different nematode strains. An increased expression of the ace genes might contribute to fenamiphos-insensitivity as seen in the Rl isolate.
Topics: Acetylcholinesterase; Animals; Cholinesterase Inhibitors; Dose-Response Relationship, Drug; Down-Regulation; Gene Expression; Lethal Dose 50; Molecular Docking Simulation; Nematoda; Organophosphorus Compounds; Up-Regulation
PubMed: 35132122
DOI: 10.1038/s41598-022-05998-y -
EFSA Journal. European Food Safety... Jan 2019The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State Greece and... (Review)
Review
The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State Greece and co-rapporteur Member State Cyprus for the pesticide active substance fenamiphos are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of fenamiphos as a nematicide in fruiting vegetables (i.e. tomato, aubergine, cucumber, pepper and courgette), herbaceous ornamentals and in nursery stock (both perennial and herbaceous species). The reliable end points, appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.
PubMed: 32626102
DOI: 10.2903/j.efsa.2019.5557 -
Journal of Nematology Dec 1996Avermectin B, isazofos, and fenamiphos were evaluated in greenhouse experiments for efficacy against two common turfgrass parasites, Hoplolaimus galeatus and...
Avermectin B, isazofos, and fenamiphos were evaluated in greenhouse experiments for efficacy against two common turfgrass parasites, Hoplolaimus galeatus and Tylenchorhynchus dubius. Treatments in all experiments were arranged in a completely randomized design and replicated four times. In the first experiment, avermectin B at rates of 0.2 and 0.4 kg a.i./ha and isazofos at rates of 2.3 and 23 kg a.i./ha significantly reduced populations of both species of parasitic nematodes compared to controls at 14 and 28 days after treatment (P = 0.01). In the second experiment, the greatest reductions in both nematode populations occurred at 28 and 56 days after treatment, where 23 kg a.i./ha of isazofos was applied (P = 0.01). These reductions, however, were not different from reductions of H. galeatus at 28 and 56 days after treatment (P = 0.01) or T. dubius at 56 days after treatment (P = 0.01), where 0.2- and 0.4-kg a.i./ha rates of avermectin B were mixed throughout the soil. In the third experiment, the greatest population reduction of H. galeatus was observed with a 0.4-kg a.i./ha treatment of avermectin B at 56 days after treatment (P = 0.05). T. dubius populations were reduced by the 0.4-kg a.i./ha rate of avermectin B at 28 (P = 0.01), 56 (P = 0.05), and 70 (P = 0.01) days after treatment. In the fourth and fifth experiments, avermectin B at rates of 7.5 and 15.2 kg a.i./ha consistently reduced nematode populations compared to controls and performed as well or better than fenamiphos (P = 0.01).
PubMed: 19277196
DOI: No ID Found -
Journal of Nematology Dec 1994Field and greenhouse experiments were conducted to determine the extent to which fenamiphos and its degradation products, fenamiphos sulfoxide and fenamiphos sulfone,...
Field and greenhouse experiments were conducted to determine the extent to which fenamiphos and its degradation products, fenamiphos sulfoxide and fenamiphos sulfone, are available to contact nematodes in the soil. Water extraction provided a relative measure of each chemical's availability to the soil water where the chemicals could contact nematodes, and methanol extraction provided a relative measure of the total amount of each chemical present in the soil. Only small amounts of fenamiphos and fenamiphos sulfone could be extracted by water, even when much larger amounts were present in the soil. In contrast, virtually all of the fenamiphos sulfoxide present in the soil was extractable by water several days after nematicide application. Three days after fenamiphos (3EC) was applied at 6.7 kg a.i./ha to field plots, 6.4% of the fenamiphos, 14.4% of the fenamiphos sulfone, and 100% of the fenamiphos sulfoxide present in the soil was extracted by water. In greenhouse experiments with soil from these field plots, a 15G formulation of fenamiphos containing 98.7% fenamiphos and 1.3% fenamiphos sulfoxide was added to the soil. After an initial period of 3-4 days, the sulfoxide which formed by oxidation of fenamiphos became completely available for water extraction, whereas fenamiphos remained relatively unextractable by water. Fenamiphos sulfoxide is much more available to soil water, thus available for contact with nematodes, than are fenamiphos or fenamiphos sulfone. Based on this availability in water, it seems likely that fenamiphos sulfoxide is the major component for controlling nematodes.
PubMed: 19279923
DOI: No ID Found -
Journal of Nematology Dec 1994A nematicide (fenamiphos) and a herbicide (EPTC) were injected into a sprinkler irrigation system separately and as tank mixtures and applied in 25.4 kl water/ha for...
A nematicide (fenamiphos) and a herbicide (EPTC) were injected into a sprinkler irrigation system separately and as tank mixtures and applied in 25.4 kl water/ha for nematode and weed control on snapbean. There were no differences (P = 0.05) between methods of injection of fenamiphos + EPTC on efficacy or crop response. The root-gall indices of cultivars Eagle and GV 50 were lower in fenamiphos-treated plots than those treated with EPTC alone and untreated plots. The yield and crop value were greater (P = 0.05) for cultivars Eagle and Nemasnap than GV 50. Fenamiphos 4.48 kg a.i./ha + EPTC 3.36 kg a.i./ha controlled root-knot nematodes, Meloidogyne incognita, ring nematodes, Criconemella ornata, and weeds, and resulted in greater plant growth, yield, and crop value than those from untreated plots. No benefits (P = 0.05) resulted from treatment with fenamiphos at 6.72 kg a.i./ha + EPTC treatment compared with fenamiphos at 4.48 kg a.i. + EPTC.
PubMed: 19279949
DOI: No ID Found -
Journal of Nematology Jan 1991The ability of Caenorhabditis elegans to recover from exposure to high doses of aldicarb and fenamiphos was examined at the organismal and biochemical levels by...
The ability of Caenorhabditis elegans to recover from exposure to high doses of aldicarb and fenamiphos was examined at the organismal and biochemical levels by determination of movement and acetylcholinesterase activity. Nematodes recovered rapidly from a 24-hour exposure to both compounds at concentrations that caused complete paralysis. Acetylcholinesterase regained nearly full activity after a 24-hour exposure to aldicarb but only 10% activity after exposure to fenamiphos. The nematodes were able to move normally, however, on the limited activity that was regained after fenamiphos treatment. Mutant C. elegans strains deficient in various molecular forms of acetylcholinesterase were utilized to demonstrate that the mechanism of recovery did not involve new synthesis of enzyme. This result was confirmed by experiments on acetylcholinesterase reactivation from live versus dead nematodes.
PubMed: 19283090
DOI: No ID Found -
Journal of Nematology 2020The nematicidal activity of crudely milled powders of stems, leaves, and bulbs of , , , , , , , and on eggs and J2 population densities of race 2 on tomato was...
The nematicidal activity of crudely milled powders of stems, leaves, and bulbs of , , , , , , , and on eggs and J2 population densities of race 2 on tomato was examined under glasshouse conditions. These plant species have medicinal properties and are being used in South Africa by traditional healers as so-called "muti." All plant species showed a suppressive effect. Relative to untreated control, the soil amendments consistently suppressed population densities in tomato roots and the reproductive potential (RP) of the nematode. When compared to fenamiphos, a commercial systemic chemical nematicide, the soil amendments performed comparable or better in suppressing nematode populations in the root systems in 2008 and 2009, but fenamiphos performed better than all soil amendments in 2011. The RP of was comparable for both soil amendment- and fenamiphos-treated plants. No consistent trend in the effect of the soil amendments on plant root and shoot bioweight was observed, except when plants were treated with -based soil amendments and both root and shoot bioweight were consistently higher compared with untreated control plants. Our results show that the plant species examined are potential sources of phytonematicides effective against race 2. The nematicidal activity of crudely milled powders of stems, leaves, and bulbs of , , , , , , , and on eggs and J2 population densities of race 2 on tomato was examined under glasshouse conditions. These plant species have medicinal properties and are being used in South Africa by traditional healers as so-called “muti.” All plant species showed a suppressive effect. Relative to untreated control, the soil amendments consistently suppressed population densities in tomato roots and the reproductive potential (RP) of the nematode. When compared to fenamiphos, a commercial systemic chemical nematicide, the soil amendments performed comparable or better in suppressing nematode populations in the root systems in 2008 and 2009, but fenamiphos performed better than all soil amendments in 2011. The RP of was comparable for both soil amendment- and fenamiphos-treated plants. No consistent trend in the effect of the soil amendments on plant root and shoot bioweight was observed, except when plants were treated with -based soil amendments and both root and shoot bioweight were consistently higher compared with untreated control plants. Our results show that the plant species examined are potential sources of phytonematicides effective against race 2.
PubMed: 32270654
DOI: 10.21307/jofnem-2020-029 -
Food and Chemical Toxicology : An... Dec 2020Fenamiphos (FS) is a chiral organophosphate pesticide that is used to control nematodes in several crops. Enantioselective differences may be observed in FS activity,...
Fenamiphos (FS) is a chiral organophosphate pesticide that is used to control nematodes in several crops. Enantioselective differences may be observed in FS activity, bioaccumulation, metabolism, and toxicity. Humans may be exposed to FS through occupational and chronic (food, water, and environmental) exposure. FS may cause undesirable CYP450 pesticide-drug interactions, which may impact human health. Here, the CYP450 isoforms involved in enantioselective FS metabolism were identified, and CYP450 inhibition by rac-FS, (+)-FS, and (-)-FS was evaluated to obtain reliable information on enantioselective FS risk assessment in humans. CYP3A4 and CYP2E1 metabolized FS enantiomers, and CYP2B6 may participate in rac-FS metabolism. In addition, rac-FS, (+)-FS, and (-)-FS were reversible competitive CYP1A2, CYP2C19, and CYP3A4/5 inhibitors. High stereoselective inhibition potential was verified; rac-FS and (-)-FS strongly inhibited and (+)-FS moderately inhibited CYP1A2. Stereoselective differences were also detected for CYP2C19 and CYP3A4/5, which were strongly inhibited by rac-FS, (+)-FS, and (-)-FS. Our results indicated a high potential for CYP450 drug-pesticide interactions, which may affect human health. The lack of stereoselective research on the effect of chiral pesticides on the activity of CYP450 isoforms highlights the importance of assessing the risks of such pesticides in humans.
Topics: Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Drug Interactions; Humans; Isoenzymes; Microsomes, Liver; Organophosphorus Compounds; Pesticides; Recombinant Proteins
PubMed: 33127494
DOI: 10.1016/j.fct.2020.111826 -
Journal of Nematology Dec 1993The effect of aldicarb and fenamiphos on Tylenchulus semipenetrans population densities and on orange yield was investigated during a 3-year (1986-88) field trial in...
The effect of aldicarb and fenamiphos on Tylenchulus semipenetrans population densities and on orange yield was investigated during a 3-year (1986-88) field trial in Italy. Rates were 10 and 20 kg a.i./ha as an early spring single application, 5 kg a.i./ha in spring and 5 kg after flowering, and 5 kg a.i. in spring followed by 2.5 kg/ha after flowering and 2.5 kg/ha in early autumn. Rates and times of application of the two nematicides did not affect numbers of females of T. semipenetrans on the roots but suppressed (P = 0.05) egg, male, and second-stage juvenile population densities from October 1986 to 1988. Yield of fruit was not affected by any treatment during 1986-87. Yield was increased (P = 0.05) in 1988 by i) a single application of 20 kg a.i./ha aldicarb, ii) 10 kg a.i./ha fenamiphos, and iii) an application of 5 kg a.i. aldicarb/ha in spring, followed by two more applications of 2.5 kg/ha each in June and September. Fruit size was not affected by the nematicide treatments. Concentrations of fenamiphos and its metabolites, in rind and pulp, were below 0.02 ppm.
PubMed: 19279837
DOI: No ID Found