Impact of transgenic insect-resistant maize HGK60 with Cry1Ah gene on community components and biodiversity of arthropods in the fields

transgenic maize cultivation showed no adverse effects on the biodiversity of epigeal arthro- pods and soil macro-organisms in the field. Some studies have proved that the fungi and their metabolites in the soil can control the insect pests [20]. Large use of chemical reagents in arthropod control resulted in pesticides resistance [21]. Insect-resistant GM crop production can improve the biodiversity of animals and plants, the biological control of pests and diseases, as well as reduction of chemical inputs [19]. It is foreseeable that microbial-based pest control could be an attractive alternative to chemical insecticides in the future. In this study, we inves- tigated the species and quantity of arthropods in the fields and analyzed the effects of trans- genic insect-resistant maize HGK60 with Cry1Ah gene on the diversity of arthropods, which can provide a scientific basis for the evaluation of the environmental safety of this type of GM maize. 2. Materials and methods 2.1 Experimental material and experimental design The experimental site of this study is Langfang Agricultural High-Tech Industrial Park belongs to Chinese Academy of Agricultural Sciences(39˚36’N, 116˚36’E), which has a temperate semi- humid continental climate with an annual average temperature of 11.9˚C, 2660 annual sun- shine hours, annual average precipitation of 554.9 mm, and sandy loamand clay loam soils with neutral pH. The experimental site is being cultivated with HGK60 maize for more than 10 years. A randomized block design was used in this study. We used the transgenic insect-resistant

maize HGK60 with Cry1Ah gene (HGK60 for short) and the common maize Zheng 58 (Z58 for short), which were provided by Chinese Academy of Agricultureal Sciences (Beijing, China). There were 4 replicates of samples, with 10 m ×10 m per plot. 1 m wide isolation belt was set among different plots, and the planting mode was one hole one grain, one hole two grains cycle sowing. The distance between maize plants was 25 cm, and the row spacing was 60 cm. The growing season for maize is between May and September in 2019 and 2020. The maize was planted on 1 May and harvested on 1 September. No fertilizer was applied, and no pesticides were sprayed during the growth process. Maize was bagged and artificially polli- nated at heading stage. The frequency of watering was a regular half a month, topdressing period is nine leaves to eleven leaves, the weeding effect applied after the seedling and pollination. 2.2 Sample collection and processing The direct observation method, trap survey method and sweeping method were used to collect samples at seedling, bell, heading and full ripe stage of the maize growth period. Each plot was sampled by a five-point sampling method three times in each growth period. The direct obser- vation method mainly investigated the species and quantity of arthropods on plants, and 15 maize plants were investigated and recorded at each point. The trap survey method mainly investigated the species and quantity of surface arthropods. Each plot was sampled by a five- point sampling method. Each point had 5 plastic cups with a diameter of 7.5 cm, each plastic

cup has a interval of 0.5 m, and a 5% antifreeze fluid is placed in the cups accounting for 1/3 of the volume of the cup. After 24 h, all the specimens were put into bottles containing 70% alco- hol. The specimens were brought back to the laboratory and were screened for counting and species identification. The sampling time of sweeping method was 16:00 to 19:00 [22]. Each plot was sampled by a five-point sampling method, and 10 plants were inspected randomly at each point, with 50 samples per plot. The sampling method was carried out 10 times on the stems and leaves of the maize plant from top to bottom using an insect net with a diameter of PLOS ONE Impact of transgenic insect-resistant maize HGK60 with Cry1Ah gene PLOS ONE | https://doi.org/10.1371/journal.pone.0269459 June 3, 2022 3 / 13