Degradation of some insecticides and their metabolites during maize silage under laboratory conditions

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Azar İ., Kumral N. A.

5th Agriculture, Environment and Health Congress, Aydın, Turkey, 17 February 2022, pp.130

  • Publication Type: Conference Paper / Summary Text
  • City: Aydın
  • Country: Turkey
  • Page Numbers: pp.130
  • Bursa Uludag University Affiliated: Yes


The aim of this study was to monitor the degradation of some insecticides (chlorpyrifos-ethyl, deltamethrin and imidacloprid) and their metabolites [3,5,6-trichloro-2-pyridinol (TCP), diethyl phosphate (DP), diethyl thiophosphate (DTP), chlorpyrifos-oxon (CO), 3-phenoxybenzoic acid (3PBA), 3-(4-hydroxyphenoxy) benzoic acid (4HPBA), imidacloprid-olefin (IMO), imidacloprid guanidine (IMG), 6-hydroxynicotinic acid (6HNA), and 6-chloronicotinic acid (6CNA)] during the 200-day fermentation period of silage samples. The research question of this study is that the maize fermentation processes could affect the degradation of applied insecticides and their metabolites. Because, lactic acid bacteria (LAB) convert water-soluble carbohydrates into different organic acids, resulting in a pH drop to protect the forage against harmful bacteria during the ensiling process. Thus, acidic conditions occurred in maize silage and insecticides are metabolized by microorganisms present in the fermentation environment. In current study, these insecticides were applied separately to maize plants grown in a controlled manner without using pesticides under laboratory conditions. Some of the spiked maize plants were left to dry and the other part was made silage in jars and kept in laboratory conditions. In order to determine the effect of fermentation, the insecticides and their metabolites applied in both dried and silage samples were analysed periodically using LC–MSMS. Organic acid, microbiology and pH analyses were performed on silage samples in each sampling period in order to determine the maturation status of the silages. In silage samples, the degradation of chlorpyrifos-ethyl, deltamethrin and imidacloprid was less with rates of 46, 45 and 30%, respectively, compared with the control samples (67, 55 and 61%,) 200 days after the insecticide application. The present study showed that the presence of LAB in the maize fermentation accelerated pH decline, and these conditions probably decelerated the degradation of these insecticides.