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

30 cm. All the specimens were put into bottles containing 70% alcohol and were killed. The specimens were brought back to the laboratory and were screened for counting and species identification [23]. The specimens were stored in Chinese Research Academy of Environmen- tal Sciences. The investigation was conducted for two consecutive years. According to the method of Hao, arthropod communities were roughly divided into four groups according to the position (trophic level) in the food chain: predatory, herbivorous, par- asitic and neutral (including saprophytic groups and groups that are neither harmful to plants nor eat other insects). Species in Araneida (Arachnida) were classified as predatory groups [24]. 2.3 Data analysis A 2-year experiment of community composition and abundances of arthropods in fields was carried out. The community structure and composition of arthropods in the fields were ana- lyzed. Survey data were presented as the means ± standard deviation of 4 replicates. Statistical analysis was performed by t-test using SPSS 16.0. A significance level of 0.05 was set for all tests. Richness index(Dmg): Dmg = (S-1)/lnN. Here, S is the number of species, N is the number of individuals Diversity index(H):H ¼ Xs i¼1 Pi ln Pi. Here, Pi is the ratio of the number of the ith individ- ual to the total number of individuals. Dominance index(D):D ¼ 1 Xs i¼1 Pi 2 Evenness index(J): J = H/lnS [25–27] The community similarity coefficient used was the Sorensen or Zekanovski coefficient (C’):

C’ = 2W/(a+b) [28], where W is the number of species shared by HGK60 and Z58, a is the total number of species in HGK60, and b is the total number of species in Z58. Values of 0.75 � C’ < 1.0 indicate very similar, 0.5 � C’ < 0.75 indicates moderately similar, 0.25 � C’ < 0.5 indi- cates moderately dissimilar, and 0 < C’ < 0.25 indicates very dissimilar. The regulation of natural group and neutral group on herbivorous groups in arthropod community was reflected by the numerical value of Nn/Np, Nd/Np, Sn/Sp and Sd/Sp. Nn/Np is the ratio of the number of individuals of natural group to that of herbivorous group; Nd/Np is the ratio of the number of individuals of neutral group to that of herbivorous group; Sn/Sp is the ratio of the number of species of natural group to that of herbivorous group; Sd/Sp is the ratio of the number of species of neutral group to that of herbivorous group [29]. The species of natural group in this study included both predatory and parasitic groups. 3. Results 3.1 Arthropod community composition in the fields A total of 124 species and 38537 individuals were observed from the experiment, belonging to 11 orders and 40 families (S1 Table). Among them, there were 4 families (10.00%) and 12 spe- cies (9.68%) of Lepidoptera, 6 families (15.00%) and 19 species (15.32%) of Hemiptera, 4 fami- lies (10.00%) and 22 species (17.74%) of Homoptera, 3 families (7.50%) and 9 species (7.26%) of Orthoptera, 1 family (2.50%) and 4 species (3.23%) of Neuroptera, 3 families (7.50%) and 12

species (9.68%) of Coleoptera, 1 family (2.50%) and 2 species (1.61%) of Thysanoptera, 6 fam- ily (15.00%) and 16 species (12.90%) of Diptera, 8 family (20.00%) and 14 species (11.29%) 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 4 / 13