title: Penetrative and dislodgeable residue characteristics of 14C-insecticides in apple fruit.
abstract: Infinite- and finite-dose laboratory experiments were used to study the penetrative and dislodgeable residue characteristics of (14)C-insecticides in apple fruit. The differences in dislodgeable and penetrated residues of three radiolabeled insecticides ((14)C-thiamethoxam, (14)C-thiacloprid, and (14)C-indoxacarb), applied in aqueous solution with commercial formulations, were determined after water and methanol wash extractions. The rate of sorption and extent of penetration into the fruit cuticles and hypanthium of two apple cultivars were measured after 1, 6, and 24 h of treatment exposure, using radioactivity quantification methods. For all three compounds, 97% or more of the treatment solutions were found on the fruit surface as some form of non-sorbed residues. For indoxacarb, sorption into the epicuticle was rapid but desorption into the fruit hypanthium was delayed, indicative of a lipophilic penetration pathway. For the neonicotinoids, initial cuticular penetration was slower but with no such delay in desorption into the hypanthium.
authors.affiliation: Department of Entomology, Michigan State University, 243 Natural Science Building, East Lansing, Michigan 48824-1115, USA.
authors.forename: David
authors.initials: D
authors.lastname: Mota-Sanchez
authors.forename: Bert
authors.initials: B
authors.lastname: Cregg
authors.forename: Eric
authors.initials: E
authors.lastname: Hoffmann
authors.forename: James
authors.initials: J
authors.lastname: Flore
authors.forename: John C
authors.initials: JC
authors.lastname: Wise
mesh_terms: D000042:Absorption; D002250:Carbon Radioisotopes; D005638:Fruit / Q000737:chemistry / Q000378:metabolism*; D007306:Insecticides / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism*; D007553:Isotope Labeling; D027845:Malus / Q000378:metabolism*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000032:analysis / Q000378:metabolism; D010078:Oxazines / Q000032:analysis / Q000378:metabolism; D010573:Pesticide Residues / Q000032:analysis; D011725:Pyridines / Q000032:analysis / Q000378:metabolism; D012996:Solutions; D000077922:Thiamethoxam; D013843:Thiazines / Q000032:analysis / Q000378:metabolism; D013844:Thiazoles / Q000032:analysis / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D010573:Pesticide Residues; D011725:Pyridines; D012996:Solutions; D013843:Thiazines; D013844:Thiazoles; C401104:indoxacarb; D000077922:Thiamethoxam; C417209:thiacloprid