Date Published: April 18, 2018
Publisher: Springer Berlin Heidelberg
Author(s): Xiaolin Zhu, Shaomin Zhou, Jing Guo, Xiyue Zhao, Guanghua Yang, Zhiqiang Cai.
Paichongding (IPP) is a neonicotinoid chiral insecticide with independent intellectual property in China. IPP application can increase crop yield, and also lead to insecticide residue and pollution in soils, which will affect microbial population and community composition in soils. In this study, four different types of soils were employed to inquire into the impact of IPP on eukaryal community and species-group through pyrosequencing of 18S rRNA gene amplicons. Fungal population differed in different soils at different days after IPP treatment (DAT). Eukaryal community species in CK (control check) groups were more rich than that with Paichongding sprayed at 5 DAT, while eukaryal species in CK soils at 60 DAT was relatively slight. Shannon’s H’ analysis indicated fungal species in CK soils were also higher at 5 DAT and relative lower at 60 DAT, except in soil C. There are also differences in the phyla and genus levels of the eukaryotic communities in the soil. After IPP application, the relative abundance of Nectriaceae increased 3–4 times in soil C. In soil F, Phaeosphaeriaceae increased to 57.3% at 5 DAT. The genus of Guehomyces, Aspergillus and Alternaria increased from 3.1 to 9.7, 1.1 to 4.6, 1.5 to 6.7% in soil H, respectively.
Soil microorganism play the most important roles on soil productivity and fertility, including organic matter decomposing, nutrient cycling, and soil aggregates forming (Six et al. 2004), they can change soil chemical and physical properties. Some bacteria and fungi are responsible for providing nutrients and essential materials, which can promote crop growth (Eo and Park 2016; Esitken et al. 2010). Pesticides are more and more popular in modern agriculture in order to control weeds, kill insects, improve the quality and yield of agricultural products. However, pesticides can enter soils via spraying draft during plant treatment, wash-off from treated foliage, release from seeds (Cycon et al. 2013). Pesticide residue in soil affect microbial community composition in soils by altering their population, enzyme activity and microbial diversity, which perhaps reduce soil fertility (Asad et al. 2017; Cai et al. 2016a, b; Zabaloy et al. 2012; Zhang et al. 2014).
The research results indicated that significant difference of fungal population existed before and after IPP spraying in anaerobic soils. The degradation efficiency and transformation rate of organic pollutants (such as pesticide, germicide and insecticide, etc.) in soils mainly depended on soil microbial population and its activity (Asad et al. 2017; Cycon et al. 2013; Eo and Park 2016; Kuppusamy et al. 2016). The chemical and biological processes in soils can lead to fungal population, including enzymatic reaction and organic pollutants biological behavior etc., response to an ecological disturbance, which depend on the presence of pesticide or insecticide (Asad et al. 2017; Cycon et al. 2013; Eo and Park 2016; Zabaloy et al. 2012). The change of microbial population and soil enzyme activity after insecticide application varied differently in different soils, which lead to hardly predict with certain model, because many inter reactions in soils existed in different conditions. The results indicated that the soil enzyme activity and fungal population were affected after IPP application, soil enzyme activity is one of key factors during nutrient cycling in soils (Asad et al. 2017; Cai et al. 2015a, 2016b). Neonicotinoid insecticides are high toxicity to vertebrates, and its use has been partly restricted for their effects on pollinators (Zeng et al. 2013). This study also suggested that IPP also can inhibit fungal population and has toxicity to fungi, which are in accord with published reports (Cai et al. 2016a, b).