title: The enhanced biodegradation of fenamiphos in soils from previously treated sites and the effect of soil fumigants.
abstract: The application of fenamiphos either alone or in combination with soil fumigants is a common practice in greenhouses and potato-cultivation areas in Greece. However, repeated applications of fenamiphos in the same field for a number of years can lead to the development of enhanced biodegradation of the nematicide. Studies in previously treated greenhouse sites and potato field sites in Greece were employed in order to investigate the development of enhanced biodegradation of fenamiphos and the respective effect of soil fumigants on the development of the phenomenon. Enhanced biodegradation of fenamiphos in a soil from a previously treated greenhouse site from the area of Aggelohori in Northern Greece was observed using both incubation and bioassay studies with nematodes. Fumigation of the enhanced soil with methyl bromide (MeBr) only temporarily inhibited degradation of fenamiphos unlike metham sodium (MS) whose application significantly reduced microbial degradation of fenamiphos. Similarly, enhanced biodegradation of fenamiphos was evident in soil from potato fields that had a history of previous exposure to fenamiphos. The slow rates of fenamiphos degradation observed in soils from the previously treated sites after sterilization with broad-spectrum antibiotics and also in soils from previously untreated sites suggested that soil microorganisms were responsible for its rapid degradation. The inhibition of enhanced biodegradation of fenamiphos in soil from the previously treated greenhouse site caused by the antibiotic penicillin probably indicates that Gram+ or other bacteria sensitive to penicillin are responsible for the rapid degradation of fenamiphos in this soil. No cross-adaptation was observed between fenamiphos and other nematicides registered in Greece for the control of root-knot and potato cyst nematodes, including cadusafos, ethoprophos, and oxamyl. According to our results, applications of MS followed by fenamiphos or in rotation with other registered nematicides are the most promising means for minimizing the risk of development of enhanced biodegradation of fenamiphos in soils.
authors.affiliation: Laboratory of Pesticide Science, Aristotle University of Thessaloniki, School of Agriculture, Department of Crop Protection, 54124 Thessaloniki, Greece. dkarpouz@agro.auth.gr
authors.forename: Dimitrios Georgios
authors.initials: DG
authors.lastname: Karpouzas
authors.forename: Polydoros
authors.initials: P
authors.lastname: Hatziapostolou
authors.forename: Euphemia
authors.initials: E
authors.lastname: Papadopoulou-Mourkidou
authors.forename: Ioannis O
authors.initials: IO
authors.lastname: Giannakou
authors.forename: Athena
authors.initials: A
authors.lastname: Georgiadou
mesh_terms: D000220:Adaptation, Biological / Q000187:drug effects; D000818:Animals; D001673:Biodegradation, Environmental / Q000187:drug effects; D018533:Biomass; D005651:Fumigation / Q000379:methods*; D006115:Greece; D006842:Hydrocarbons, Brominated / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000032:analysis* / Q000737:chemistry; D010575:Pesticides; D018517:Plant Roots / Q000469:parasitology; D012987:Soil / Q000032:analysis; D013859:Thiocarbamates / Q000737:chemistry; D013997:Time Factors; D014431:Tylenchoidea / Q000472:pathogenicity
chemical_list: D006842:Hydrocarbons, Brominated; D009943:Organophosphorus Compounds; D010575:Pesticides; D012987:Soil; D013859:Thiocarbamates; C008435:methyldithiocarbamate; C005218:methyl bromide; C002698:fenamiphos