Neonicotinoid insecticides translocated in guttated droplets of seed-treated maize and wheat: a threat to honeybees?
- 743 Downloads
The immune system of bees is influenced by a diversity of factors, some of which have changed in the last 10 years such as the application of pesticides. In addition to pollen, nectar and dust, guttated water of seed-dressed plants might be a new source of contamination to bees. Our experiments demonstrated that guttated water of plants germinated from seeds dressed with neonicotinoids contains neonicotinoids. Maize seeds treated with clothianidin (Poncho® 0.5 mg/seed and Poncho® Pro 1.25 mg/seed) resulted in neonicotinoid concentrations up to 8,000 ng mL−1 in the guttated fluid. This concentration decreases rapidly, but remained detectable over several weeks. Seeds treated with Poncho® Pro did not result in higher concentrations in guttated droplets in the first stages of plant development, but the concentration decreased more slowly. Triticale seed treated with imidacloprid contained small quantities of this active agent (up to 13 ng mL−1) in the guttated fluid the following spring after overwintering. During the sampling of guttation fluid, no bees were observed collecting these droplets from triticale or maize. To evaluate the attractiveness of guttation fluid exuded from seed-treated plants under field conditions, more studies are required.
Keywordsseed coating neonicotinoids guttated fluid Apis mellifera LC-HR-MS
The authors thank the staff members of the field site Heidfeldhof for assistance and providing us experimental sites. Furthermore, we thank Dr. Helen M. Thompson for proofreading the manuscript.
- Butler, C.G. (1940) The choice of drinking water by the honeybee. J. Exp. Biol. 17, 253–261Google Scholar
- Decourtye, A., Devillers, J., Genecque, E., Le Menach, K., Budzinski, H., Cluzeau, S., Pham-Delègue, M.-H. (2005) Comparative sublethal toxicity of nine pesticides on olfactory learning performances of the honeybee Apis mellifera. Arch. Environ. Contam. Toxicol. 48, 242–250PubMedCrossRefGoogle Scholar
- Rosenkranz, P., Wallner, K. (2009) The chronology of honey bee losses in the Rhine Valley during spring 2008: an example of worst case scenario. Proceedings of the Third European Conference of Apidologie, Dublin, Ireland, 7–11 September 2008, 94–95Google Scholar
- Schmuck, R. (1999) Imidacloprid - Kein Zusammenhang zwischen Saatgutbeizung mit Gaucho® in Sonnenblumen und Bienenschäden in Frankreich. Pflanzenschutz-Nachr. Bayer 52, 267–310Google Scholar
- Schmuck, R., Keppler, J. (2003) Clothianidin—ecotoxicological profile and risk assessment. Pflanzenschutz-Nachrichten Bayer 56, 26–58Google Scholar
- Wallner, K. (2006) Pflanzenschutzmitteleinsatz in blühende Kulturen und der Wirkstofftransport in Bienenvölker. BVL - Das “Bienensterben” im Winter 2002/2003 in Deutschland, 60–67Google Scholar
- Wallner, K. (2009) Sprayed and seed dressed pesticides in pollen, nectar and honey of treated oil seed rape. Hazard of pesticides to bees. Julius Kühn-Archiv 423, 152–153Google Scholar