The effects of pollution by multiple metals derived from long-term smelting activities on soil mite communities in arable soils under different land use types in East China.

Soil pollution represents a threat to soil biodiversity and to soil and human health. However, many ecotoxicological issues, such as the impact of heavy metal pollution on the soil mite community and its spatial distribution in areas with complex environmental factors, are not fully understood. Here, an investigation was conducted in an arable area (about 11 km2) enclosed by surrounding mountains. The study area was contaminated with potentially toxic metals derived from copper smelting that was functioning for over 10 years. The area comprised four land use types: woodlands, dry fields, paddy fields, and wastelands, and was divided into 141 study sites each with an area of 6.25 ha. The soil metal (Cu, Zn, Pb, and Cd) contents, pH, and organic matter were determined and their distributions were established. Furthermore, soil mite (Acari) community properties (species richness, individual abundance, and Shannon-Wiener diversity index) were determined, and the distributions of total species number and abundance were ascertained. Soil metal pollution strongly reduced soil mite community, but the effects depended on mite groups or species and their sensitivity to different metals as well as land use types. CANOCO analysis revealed that the order Oribatida was more highly correlated with soil metal contents, whereas the other three orders responded to soil metal contents depending on land use types, mite properties, or metals. SADIE method indicated that the coordinate relationship between mite species number and metal concentration was more negative (4-25% of the study sites) than positive (4-12%). The metal pollution levels in the soil were evaluated by single and integrated pollution and ecological risk indices.

Occurrence and distribution of microplastics in coastal plain soils under three land-use types.

Microplastic pollution is an issue of major environmental concern worldwide. Land-use type may affect the abundance, polymer types, and distribution characteristics of soil microplastics but their distribution remains unknown on the coastal plain of east China. Here, the abundance of microplastics in farmland (FL), plantation (P), and orchard/secondary forest (OSF) soils was determined on the east China coastal plain, and characteristics of the microplastics (shape, size, colour, and polymer composition) were analysed in soil samples collected from 33 sites. The average abundances of microplastics in FL, P, and OSF soils on the coastal plain of the east China coast were 185, 109, and 150 items kg-1, respectively. Small particles, fibres and transparent particles were the main characteristics of the microplastics observed. The polymer types were mainly PP and PET. The abundance of microplastics in farmland was positively correlated with population density in the study area. Therefore, agricultural activities associated with high population density are the main factors leading to the high abundance of microplastics in farmland soil.

High-quality genomes reveal significant genetic divergence and cryptic speciation in the model organism Folsomia candida (collembola).

The collembolan Folsomia candida Willem, 1902, is widely distributed throughout the world and has been frequently used as a test organism in soil ecology and ecotoxicology studies. However, it is questioned as an ideal "standard" because of differences in reproductive modes and cryptic genetic diversity between strains from various geographical origins. In this study, we obtained two high-quality chromosome-level genomes of F. candida, for a parthenogenetic strain (named FCDK, 219.08 Mb, 25,139 protein-coding genes) and a sexual strain (named FCSH, 153.09 Mb, 21,609 protein-coding genes), reannotated the genome of the parthenogenetic strain reported by Faddeeva-Vakhrusheva et al. in 2017 (named FCBL, 221.7 Mb, 25,980 protein-coding genes) and conducted comparative genomic analyses of the three strains. High genome similarities between FCDK and FCBL based on synteny, genome architecture, mitochondrial and nuclear gene sequences suggest that they are conspecific. The seven chromosomes of FCDK are each 25%-54% larger than the corresponding chromosomes of FCSH, showing obvious repetitive element expansions and large-scale inversions and translocations but no whole-genome duplication. The strain-specific genes, expanded gene families and genes in nonsyntenic chromosomal regions identified in FCDK are highly related to the broader environmental adaptation of parthenogenetic strains. In addition, FCDK has fewer strain-specific microRNAs than FCSH, and their mitochondrial and nuclear genes have diverged greatly. In conclusion, FCDK/FCBL and FCSH have accumulated independent genetic changes and evolved into distinct species after 10 million years ago. Our work provides important genomic resources for studying the mechanisms of rapidly cryptic speciation and soil arthropod adaptation to soil ecosystems.

The mitochondrial genome of a minute springtail species Megalothorax incertus (Collembola: Neelipleona: Neelidae).

In this study, the complete mitochondrial genome for the Wolbachia infected parthenogenetic collembola Megalothorax incertus Börner, 1903 was determined. It represents the first report of a complete mitochondrial genome from Neelipleona, one of the four orders of Collembola. The circularized 14,994 bp mitochondrial genome sequence consists of canonical 37 mito-genes, including 13 protein-coding genes (PCGs), 22 tRNA genes, and two rRNA genes. The base composition of the majority strand (same direction as most of the mitochondrial genes) is 32.0% for A, 24.1% for C, 11.9% for G, and 32.1% for T. The phylogenetic trees inferred from 13 PCGs using the Maximum-likelihood (ML) and Bayesian inference (BI) methods suggested that Neelidae is basal to the remaining springtails. This mitochondrial genome provides new insights to decipher the phylogeny of Collembola.

New and little known Isotomidae (Collembola) from the shore of Lake Baikal and saline lakes of continental Asia.

Collembola of the family Isotomidae from the shores of Lake Baikal and from six saline lake catenas of the Buryat Republic (Russia) and Inner Mongolia Province (China) were studied. Pseudanurophorus barathrum Potapov & Gulgenova, sp. nov. and Parisotoma baicalica Potapov & Gulgenova, sp. nov. from Baikal and Ephemerotoma buryatica Potapov, Huang & Gulgenova, sp. nov. and Folsomia mongolica Huang & Potapov, sp. nov. from saline lakes are described here. A morphological description of epitokous males of Scutisotoma acorrelata Potapov, Babenko & Fjellberg, 2006 is given. A list of 23 species of the family Isotomidae found in the shores of studied lakes is provided based on literature sources and newly collected material.

A multi-generational risk assessment of Cry1F on the non-target soil organism Folsomia candida (Collembola) based on whole transcriptome profiling.

The Bacillus thuringiensis toxin Cry1F has been used to develop insect-resistant genetically engineered crops. There has been great interest in evaluating its potential risk to non-target organisms (NTOs). However, the majority of previous risk assessments only examined one generation of NTOs using several physiological indicators, which cannot comprehensively detect some potential sub-lethal effects at the molecular level. In this study, we conducted a laboratory-based, multi-generational risk assessment of Cry1F for the collembolan Folsomia candida, an important representative of soil arthropods in terms of survival, reproduction, and differentially expressed genes (DEGs) identified from whole transcriptome profiles. Our results demonstrated that Cry1F was continuously ingested by collembolans over three consecutive generations, but it did not affect the survival or reproduction of F. candida. There were no significant differences in the global gene expression between F. candida-fed diets with and without Cry1F, and no consistent co-expressed DEGs over three generations. In addition, Cry1F did not obviously alter the expression profiles of seven sensitive biological markers. Our composite data indicates that Cry1F had no long-term harmful effects on collembolan F. candida.

A new species and a new record of Sinella Brook (Collembola: Entomobryidae) from Guizhou Province, China.

Two species of Sinella Brook were discovered in an expedition to Maolan National Nature Reserve, Guizhou Province, China: S. maolanensis sp. nov. and S. colorata Zhang, Qu Deharveng. The new species is characterized by the postlabial chaetae X, X2 and X4 ciliate and X3 smooth and the 6+6 central mac on the fourth abdominal segment. It differs from the closely related species by the combination of postlabial chaetae and abdominal chaetotaxy. Sinella colorata is a new record from the province. A key to the eyeless Sinella species from China is provided.

A new species of Lobellina and first record of Vietnura from China (Collembola: Neanuridae: Neanurinae).

A new species of Lobellina Yosii, 1956 and a key to all species of the genus is provided. It is distinguished from all known members of the genus by its unique set of morphological characters: mandible with six teeth, cephalic chaeta O present, and free from tubercle Fr, cephalic tubercle Oc with three chaetae, cephalic tubercle Di separate, and tubercle Dl with four (sometimes three) chaetae, Ant. I with eight chaetae, and claw with an inner tooth. Vietnuracaerulea Deharveng & Bedos, 2000 is recorded from China for the first time. New localities of Rambutanurahunanensis Jiang & Dong, 2018 and Vitronuraparaacuta Wang, Wang & Jiang, 2016 from southwest China are also provided.

Generic switch-over during ontogenesis in Dimorphacanthella gen. n. (Collembola, Isotomidae) with barcoding evidence.

A new genus Dimorphacanthella is established for Tetracanthella anommatos Chen and Yin, 1984 and Dimorphacanthella mediasetasp. n. from China. The new genus exhibits an unusual metamorphosis: small juveniles, previously called Uzelia anommatos Yue & Yin, 1999 get the second pair of anal spines resulted from moulting and become "Tetracanthella". Species identity of forms with two and four anal spines is proved by barcoding analysis. The derivation of anal spines is compared among genera having four anal spines.