Different residue behaviors of four pesticides in mushroom using two different application methods

Pesticide residue in mushrooms is less known. In this study, the risks of beta-cypermethrin, pyriproxyfen, avermectin, and diflubenzuron in oyster and shiitake mushrooms were evaluated using two different treatments: substrate mixture and surface spraying. Almost all the concentrations of these pesticides at day 90 were higher than 80% of the initial concentrations, while it was less than 45% for all cases within 35 days by spraying. For surface spraying, the residues of beta-cypermethrin were 0.0843-1.22 mg kg^-1 in shiitake mushrooms and below 0.005 mg kg^-1 in oyster mushrooms; the residues of pyriproxyfen, avermectin, and diflubenzuron were 0.122-4.84, 0.00501-0.111, and 0.0681-1.91 mg kg^-1, respectively. The residues of beta-cypermethrin, pyriproxyfen, and diflubenzuron in oyster mushrooms (in shiitake mushrooms) at interval of 0, 3, 5 days (1, 5, 7 days) were below their MRLs in China or Japan. The residue of avermectin in both mushrooms was lower than its limit of detection. These results provide information to safe and proper use of the pesticides in oyster and shiitake mushrooms.