Environmental hazards of nanopesticides to non-target soil species - commercial nanoformulation versus its active substance (Karate Zeon® and lambda-cyhalothrin)

Abstract

Nanopesticides (Npes) carry the potential of increased efficacy while reducing application rates, hence increasing agricultural productivity in a more sustainable way. However, given its novelty, the environmental risk assessment of these advanced materials is mostly absent. In the present study we investigated the ecotoxicity of a commercial insecticide, with reported nanofeatures, Karate Zeon®, and compared it to its active substance lambda-cyhalothrin. It is hypothesised that the use of the nanopesticide Karate Zeon® poses lower risk to enchytraeids than its active substance. The standard non-target soil invertebrate Enchytraeus crypticus was used, and exposure was done in LUFA 2.2 soil in 4 tests (endpoints: days): avoidance test [avoidance behaviour: 2 days], OECD standard reproduction test [survival, reproduction plus adults' size: 28 days] and its extension [total number organisms: 56 days], and Full Life Cycle (FLC) test [hatching and juveniles' size: 13 days; survival, reproduction and adults' size: 46 days]. Results showed that enchytraeids did not avoid Karate Zeon® nor its active substance lambda-cyhalothrin, which could be due to neurotoxicity. There was no indication of increased toxicity with prolonged exposure (46, 56d) compared to the standard (28d) for neither of the materials, being overall equally toxic in terms of hatching, survival, and reproduction. The FLCt results indicated that the juvenile stage was the most sensitive, resulting in higher toxicity for the adult animals when exposed from the cocoon stage. Although toxicity was similar between Karate Zeon and lambda-cyhalothrin, different patterns of uptake and elimination cannot be excluded. The benefits of using Karate Zeon will rely on reduced application rates.