Nano-sized Al.sub.2O.sub.3 reduces acute toxic effects of thiacloprid on the non-biting midge Chironomus riparius

• Published in: PloS one 2017-05, Vol.12 (5), p.e0176356
• Main Authors: Lorenz, Carla S, Wicht, Anna-J, Guluzada, Leyla, Luo, Leilei, Jäger, Leonie, Crone, Barbara, Karst, Uwe, Triebskorn, Rita, Liang, Yucang, Anwander, Reiner, Haderlein, Stefan B, Huhn, Carolin, Köhler, Heinz-R
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Chironomids; Health aspects; Nanoparticles; Neonicotinoid insecticides; Physiological aspects
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0176356

This study focuses on interactions between nanoparticles and a pesticide. The aim was to investigate how nano-sized aluminum oxide (410 nm) can alter the toxic effects of thiacloprid, even if no sorption between particles and the insecticide takes place. Thus, our study investigated a rather unexplored interaction. We conducted our research with larvae of Chironomus riparius and used thiacloprid as test substance as its toxicity to C. riparius is well described. The used nano-Al.sub.2 O.sub.3 particles where chosen due to their suitable properties. For testing the acute effects of the interaction, we exposed larvae to thiacloprid (0.5, 1.0, 2.0, and 5.0 [mu]g/L) and nano-Al.sub.2 O.sub.3 (300 and 1000 mg/L), either solely or in binary mixtures. While thiacloprid resulted in elevated mortality, nano-Al.sub.2 O.sub.3 solely did not exert any effects. Moreover, we observed an aggregation of nano-Al.sub.2 O.sub.3 within the lumen of the intestinal tract of the larvae. Further results showed a significantly reduced mortality of fourth instar larvae when they were exposed to mixtures of nanoparticles and the pesticide, compared to thiacloprid alone. With increasing nano-Al.sub.2 O.sub.3 concentration, this effect became gradually stronger. Additionally, chemical analyses of internal thiacloprid concentrations implicate reduced uptake of thiacloprid in animals exposed to mixtures. However, as larvae exposed to thiacloprid concentrations > 0.5 [mu]g/L showed severe convulsions, independent of the presence or concentration of nano-Al.sub.2 O.sub.3, we assume that nano-Al.sub.2 O.sub.3 leads to a delay of mortality and does not entirely prevent it. As sorption measurements on pristine or defecated nano-Al.sub.2 O.sub.3 did not reveal any sorptive interaction with thiacloprid, we can exclude sorption-based reduction of thiacloprid bioavailability as a mechanism behind our results. Even though we used test substances which might not co-occur in the environment in the tested concentrations, our study gives evidence for an interaction besides adsorption, which is important to generally understand how nanoparticles might affect biota.