Imidacloprid in melon guttation fluid: a potential mode of exposure for pest and beneficial organisms

ELISA techniques were used to detect imidacloprid in guttation fluid of young cantaloupe plants in Arizona. Imidacloprid was detected at up to 4.1 microg/ml (ppm) in a coincidental guttation collection 3 d after a top label rate soil application and at 37 microg/ml one d after a separate top label rate soil application study. These imidacloprid titers exceed reported median oral toxicities for several insect species by factors of 10 or more. Pesticides in guttation fluid are a relatively unexplored route of exposure for both pest and beneficial insects, and could represent an important risk for both of these groups in guttation-prone environments.