Persistence and downward movement of four termiticides in three representative soils of Gujarat under laboratory conditions

Abstract

Termiticides are generally applied to control the damage done by the devastating termites at pre-construction stage which are much higher than agricultural rate. Thus, such higher termiticidal application could pose a serious threat to water contamination with toxic residues. A study was performed to determine the persistency and downward movement of termiticides viz.,bifenthrin, chlorpyrifos, fipronil and imidacloprid in clay, sandy loam and sandy soils of Gujarat. The results of persistency study reveal that bifenthrin, chlorpyrifos, fipronil and imidacloprid were readily to fairly degradable and non-persistent to moderate persistent in soils (DT50 varied between 12.24-41 days) when applied at the rate of 2mg/kg (weight basis). Downward movement and depth wise distribution of these termiticides was determined by loading the pesticides at the rate of 2 mg/kg on 3 water saturated clay sandyloam and sandy soil columns. Bifenthrin residues confined to S-2 segments (6-12 cm) in all three soils while other termiticides moved from S-2 (6-12 cm) to S-5 (24-30 cm) in different soil columns. Maximum downward movement was recorded for imidacloprid in sandy soil column. The residues of above termiticides were BDL in leachates collected on any sampling day.