During 2010 and 2011 field studies were carried out at the inner-city experimental field station of JKI in Berlin with the objective to estimate the frequency of guttation in neonicotinoid treated maize (seed or granule treatment) and the content of neonicotinoids in guttation droplets under the climate conditions of Central Europe. In the meantime a high acute risk was identified for bees from exposure via guttation fluid from maize (EU 485/2013). However, there are no publications on the exposure of other non-target arthropods to imidacloprid, clothianidin and thiamethoxam via guttation droplets. In a randomized block design 11 treatment variants were sown with different application rates of these neonicotinoids. Sampling of guttation fluid started after emergence of maize at 6:30 a.m. once a day. Guttation occurred frequently. Coccinellidae (n = 36) (Coccinella quinquepunctata and C. septempunctata) were found on the upper side of leaves of maize seedlings (BBCH 13 and 14) between large guttation droplets on day 3, 5, and 11 after emergence in May 2011. No aphids were observed at the maize seedlings. Sometimes small dew drops occurred on leaf surfaces. Concentrations of neonicotinoids and their metabolites in guttation fluid decreased over time. The beetles contained, with one exception, only the a.i. and corresponding metabolites, which were applied in the treatment where the insects were collected. On day 3 the highest contents of neonicotinoids in ladybirds were measured. On day 3 and 5 eleven beetles were found in treated variants and all of them contained the neonicotinoids. By day 11, 10 out of 19 beetles contained residues. Three dead ladybirds were found in treated variants on day 11. Two of them contained residues. One beetle was dead in an untreated control.

Exposure of Coccinellidae to guttation droplets on maize seedlings with seed or granule treatment of neonicotinoids

248th National Meeting (2014)

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