Impact of the novel neonicotinoid insecticide Paichongding on bacterial communities in yellow loam and Huangshi soils

Abstract

Insecticides are widely sprayed in modern agriculture for ensuring the crop yield, which could also lead to contamination and insecticide residue in soils. Paichongding (IPP) is a novel neonicotinoid insecticide and was developed recently in China. Soil bacterial community, diversity, and community composition vary widely depending on environmental factors. As for now, little is known about bacterial species thriving, bacterial community diversity, and structure in IPP-spraying soils. In present study, IPP degradation in yellow loam and Huangshi soils was investigated, and bacterial communities and diversity were examined in soil without IPP spray and with IPP spray through pyrosequencing of 16S ribosomal RNA (rRNA) gene amplicons. The degradation ratio of IPP at 60 days after treatment (DAT) reached 51.22 and 34.01 % in yellow loam and Huangshi soil, respectively. A higher richness of operational taxonomic units (OTUs) was found in yellow loam soil (867 OTUs) and Huangshi soil (762 OTUs) without IPP spray while OUTs were relatively low in IPP-spraying soils. The community composition also differed both in phyla and genus level between these two environmental conditions. Proteobacteria, Firmicutes, Planctomycetes, Chloroflexi, Armatimonadetes, and Chlorobi were stimulated to increase after IPP application, while IPP inhibited the phyla of Bacteroidetes, Actinobacteria, and Acidobacteria.

Toxic effect of the novel chiral insecticide IPP and its biodegradation intermediate in nematode Caenorhabditis elegans

“…The toxicity differences between IPP and M1 at relatively high concentrations also occurred with the aid of head thrash, body bend, locomotion and lifespan. M1 is one of the intermediates of IPP biodegradation in environment, and also determined in soil after IPP application (Cai et al 2015a(Cai et al , 2015b(Cai et al , 2016a(Cai et al , 2016b(Cai et al , 2016cChen et al 2017;Fu et al 2013). The toxicity of toxicants in C. elegans is similar to the toxic results in mammals, the results in this study imply the possible potential more severe toxicity of IPP than M1 in mammals.…”

“…Paichongding (IPP, 1-((6-chloropydidin-3-yl) methyl)-7-methyl-8-nitro-5 -propoxy-1,2,3,5,6,7-hexahydroimidazo[1,2--]-pyridine), is a novel chiral insecticide with independent intellectual property rights developed in China (Cai et al, 2015a(Cai et al, , 2015b(Cai et al, , 2016aFu et al 2013). It has higher insecticidal activity (40-50 times) compared to imidacloprid-resistance pests, and also has low toxicity to human.…”

“…It has higher insecticidal activity (40-50 times) compared to imidacloprid-resistance pests, and also has low toxicity to human. In China IPP was used for pesticide control and sprayed for almost 3.3 million hectares (Cai et al 2016a;Chen et al 2017).…”

“…Previous studies have emphasized on the biodegradation pathway of IPP, its behavior in soils, and its effect on microbial community, soil enzyme activity etc. (Cai et al 2016a(Cai et al , 2016b(Cai et al , 2016c). However, little information is available on the toxicity of IPP and its biodegradation intermediates on protozoan in soils.…”

Enantioselectivity in degradation and ecological risk of the chiral pesticide ethiprole

“…Conversely, Gemmatimonadetes steadily increased over the period studied and was probably activated in the presence of chiral ethiprole. In contrast, Firmicutes was stimulated to grow, and Gemmatimonadetes restricted when soils were treated with a novel neonicotinoid insecticide called paichongding (Cai et al, ). These results suggest that the same bacterial phylum were influenced differently by exposure to different pesticides and different enantiomers of chiral pesticides.…”