Residue and dissipation of two formulations of emamectin benzoate in tender cowpea and old cowpea and a risk assessment of dietary intake

Abstract

The dissipation and residue levels of emamectin benzoate emulsifiable concentrate (EC) and microemulsion (ME) formulations in tender cowpeas and old cowpeas were investigated under field conditions. The decline curves of emamectin benzoate residues in cowpea corresponded to first-order kinetics. The dissipation rate of emamectin benzoate in tender cowpeas was faster than that in old cowpeas. The half-lives of the EC were 1.34–1.39 d and 1.74–2.31 d in tender cowpea and old cowpea, respectively. For the ME, the half-lives were 1.39–1.51 d and 2.08–2.67 d, respectively. The risk of adult intake of emamectin benzoate from cowpea is within the acceptable limits of the human body. Compared to tender cowpeas, the risk of eating old cowpeas is higher. Emamectin benzoate (EC) is recommended for cowpeas when the intention is to harvest tender cowpeas, while both formulations are acceptable for cowpeas when the intention is to harvest old cowpeas.