Penetrative and dislodgeable residue characteristics of 14C-insecticides in apple fruit

J Agric Food Chem. 2012 Mar 28;60(12):2958-66. doi: 10.1021/jf205169f. Epub 2012 Mar 9.

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Absorption
  • Carbon Radioisotopes
  • Fruit / chemistry
  • Fruit / metabolism*
  • Insecticides / administration & dosage
  • Insecticides / analysis
  • Insecticides / metabolism*
  • Isotope Labeling
  • Malus / metabolism*
  • Neonicotinoids
  • Nitro Compounds / analysis
  • Nitro Compounds / metabolism
  • Oxazines / analysis
  • Oxazines / metabolism
  • Pesticide Residues / analysis
  • Pyridines / analysis
  • Pyridines / metabolism
  • Solutions
  • Thiamethoxam
  • Thiazines / analysis
  • Thiazines / metabolism
  • Thiazoles / analysis
  • Thiazoles / metabolism

Substances

  • Carbon Radioisotopes
  • Insecticides
  • Neonicotinoids
  • Nitro Compounds
  • Oxazines
  • Pesticide Residues
  • Pyridines
  • Solutions
  • Thiazines
  • Thiazoles
  • indoxacarb
  • Thiamethoxam
  • thiacloprid