Use of Taxonomic and Trait-Based Approaches to Evaluate the Effect of Bt maize Expressing Cry1Ie Protein on Non-Target Collembola: A Case Study in Northeast China

To evaluate the effect of Bt maize expressing Cry1Ie protein on non-target soil Collembola, a two-year field study was conducted in Northeast China. Bt maize line IE09S034 and its near isoline Zong 31 were selected as experimental crops; we investigated the collembolan community using both taxonomic and trait-based approaches, and elucidated the relationship between environmental variables and the collembolan community using redundancy analysis (RDA).The ANOVA results showed that maize variety neither had significant effect on the parameters based on taxonomic approach (abundance, species richness, Shannon–Wiener index, Pielou’s evenness index), nor on the parameters based on trait-based approach (ocelli number, body length, pigmentation level, and furcula development) in either year. The results of RDA also showed that maize variety did not affect collembolan community significantly. These results suggest that two years cultivation of cry1Ie maize does not affect collembolan community in Northeast China.

Field decomposition of Bt-506 corn leaf and its effect on Collembola in the black soil region of Northeast China

The litters of Bt corn would go into the soil through straw returning and field ploughing after cultivation. To clarify whether the leaf litter decomposition rate and the non-target soil Collembola were influenced by the Bt protein or other litter properties in leaf litters of Bt corn in Northeast China, leaf litterbags of Bt-506, its near isoline Zheng 58 and a local type Zhengdan 958 were used in the field in Northeast China. The leaf decomposition rate, the leaf properties and the collembolan community in litterbags were investigated later. After seven months, only 43.5 ng/g Bt protein in Bt-506 leaf litter was left. All the investigated indices were not significantly different between Bt-506 and its near isoline Zheng 58. But when compared with local type Zhengdan 958, Bt-506 and its near isoline Zheng 58 contained lower non-structural carbohydrate content but higher total nitrogen content, and had lower litter decomposition rate and less abundance of Collembola. Collembolan abundance and litter decomposition rate were both significantly correlated with the non-structural carbohydrate and total nitrogen contents of the leaf litters. Field study results revealed Bt protein did not affect the leaf litter decomposition rate and the collembolan community in leaf litterbags in short term. The significant differences of these investigated indices among corn types were caused by the different non-structural carbohydrate and total nitrogen contents in leaf litter.

The degree of change of collembolan community structure related to anthropic soil disturbance

Edaphic fauna play a crucial role in soil processes such as organic matter incorporation and cycling, nutrient content, soil structure, and stability. Collembolans in particular, play a very significant role in nutrient cycling and soil structure. The structure and functioning of the soil fauna can in turn be affected by soil use, leading to changes in soil characteristics and its sustainability. Therefore, the responses of soil fauna to different soil management practices, can be used as ecological indicators. Three different soil uses were researched: agricultural fields (AG) with 50 years of continuous farming, pastures entering the agricultural cycle (CG), and naturalized grasslands (NG). For each soil use, three fields were selected. Each sampling consisted of three soil samples per replicate. Collembolans were extracted from the samples and identified to family level. Five families were found: Hypogastruridae, Onychiuridae, Isotomidae, Entomobryidae, and Katiannidae. Soils were also characterized by means of physical and chemical analyses. The index of degree of change of diversity, was calculated. The results show that the biological index of degree of change can detect soil use effects on the collembolan community. Somewhat surprisingly the index showed that the diversity of collembolans is higher in the high anthropic impact site AG, followed by CG and being lower in lower impact sites, NG. The results also show that collembolan families respond differently to soil use. The families Hypogastruridae, Onychiuridae, and Isotomidae presented differences between systems. Therefore collembolan community structure can be a useful tool to assess agricultural practices´ impacts on soil.

The degree of change of collembolan community structure related to anthropic soil disturbance

Edaphic fauna play a crucial role in soil processes such as organic matter incorporation and cycling, nutrient content, soil structure, and stability. Collembolans in particular, play a very significant role in nutrient cycling and soil structure. The structure and functioning of the soil fauna can in turn be affected by soil use, leading to changes in soil characteristics and its sustainability. Therefore, the responses of soil fauna to different soil management practices, can be used as ecological indicators. Three different soil uses were researched: agricultural fields (AG) with 50 years of continuous farming, pastures entering the agricultural cycle (CG), and naturalized grasslands (NG). For each soil use, three fields were selected. Each sampling consisted of three soil samples per replicate. Collembolans were extracted from the samples and identified to family level. Five families were found: Hypogastruridae, Onychiuridae, Isotomidae, Entomobryidae, and Katiannidae. Soils were also characterized by means of physical and chemical analyses. The index of degree of change of diversity, was calculated. The results show that the biological index of degree of change can detect soil use effects on the collembolan community. Somewhat surprisingly the index showed that the diversity of collembolans is higher in the high anthropic impact site AG, followed by CG and being lower in lower impact sites, NG. The results also show that collembolan families respond differently to soil use. The families Hypogastruridae, Onychiuridae, and Isotomidae presented differences between systems. Therefore collembolan community structure can be a useful tool to assess agricultural practices´ impacts on soil.