Naphthalene exerts non-target effects on the abundance of active fungi by stimulating basidiomycete abundance

As an arthropod biocide, naphthalene has been used in studies of the ecological functions of soil fauna for decades. However, its potential non-target effects on soil microorganisms may affect soil mineralization and litter decomposition processes. Therefore, we conducted an experiment with naphthalene adding to soil surface at a rate of 100 g·m−2 per month to examine the potential non-target effects of this treatment on soil fungal phospholipid fatty acids (PLFAs), 18S rDNA gene copy numbers and community diversity in a subalpine forest of western Sichuan, China. The results showed that naphthalene addition significantly increased fungal PLFAs but did not significantly alter fungal gene copy numbers. A total of 16 phyla, 62 genera and 147 Operational taxonomic units (OTUs) were identified through Illumina MiSeq sequencing analysis. Basidiomycota and Ascomycota were the most abundant phyla in both the control and naphthalene addition plots. Naphthalene addition did not affect the diversity or structure of the soil fungal community, but the increase in some genera of Basidiomycota might contribute to the increase in fungal PLFAs in the naphthalene addition plots. These results suggest that naphthalene exerts non-target effects on the active fungal abundance by stimulating the abundance of specific taxa in subalpine forest soils. The non-target effects of naphthalene on the fungal community should be taken into consideration when it is used to exclude soil fauna.