Effects of different substrates and casing materials on imidacloprid and prochloraz residues in Agaricus bisporus

In order to clarify the dissipation of imidacloprid and prochloraz residues in Agaricus bisporus cultivated in different cultivation, field experiments were carried out by mixing pesticides into the casing soil or spraying on the compost. The residues of imidacloprid and prochloraz in the substrates and fruiting body were determined using QuEChERS and ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The results showed that the dissipation dynamics of imidacloprid and prochloraz met the first-order reaction kinetics equation. The dissipation half-lives (t_1/2) of imidacloprid were 84.5 d, 65.4 d, 68.6 d in the conventional casing soil, plant ash soil, and coconut chaff soil, and t_1/2 of prochloraz in those soil were 23.5 d, 17.7 d and 19.0 d, respectively. In the compost with proportion of m (rice straws) : m (wheat straws)=0 : 10 (CT1) and 2 : 8 (CT2), t_1/2 of imidacloprid was 7.7 d, 8.0 d, and t_1/2 of prochloraz was 10.9 d, 12.8 d respectively. The t_1/2 of the two pesticides in different substrates had the same tendency as following: conventional casing soil > coconut chaff soil > plant ash soil, and in the compost CT2 > the compost CT1. Both pesticides were detected in three flushes of mushroom under different treatments, which indicated that the pesticides in casing soil and compost would migrate to fruiting body of the mushrooms. This study preliminarily revealed the dissipation dynamics of imidacloprid and prochloraz in different Agaricus bisporus, which provided theoretical support for the standardized use of pesticides and the reasonable selection of cultivation in industrial Agaricus bisporus.