Habitat-specific influences on insect diversity in regional landscapes: A case study of Xishuangbanna

Habitat-specific plays an important role in the maintenance of biodiversity. This study aimed to understand the influence of habitat type on the diversity of different insect groups and the differences in community structure across the regional landscape. This study also explored the distribution patterns and maintenance mechanisms of insect diversity on a large scale. From August to September 2019, the sample line survey method was used in the Xishuangbanna region to estimate the number of species and endemic species of butterflies, true bugs, and beetles in four different habitat types (reserve, secondary forest, artificial forest, and farmland) and to analyze the habitat specificity index of the insect communities, the community structure similarity, and the relationships between species richness and the ecological factors. A total of 2588 insects were collected, including 94 butterfly species (744 heads), 197 bug species (1094 heads), and 129 beetle species (750 heads). The number of insect species and endemic species in the reserve was higher than those in the other habitats, and the observed habitat specificity index of the insect community was higher than the expected value in the reserve. The observed habitat specificity index values for the other habitat types were lower than the expected values. There was no significant difference in the habitat specificity index of the insect communities in different habitat types (F_{3, 57}=2.054), but there was a significant difference in the habitat specificity index of beetles (F_{3, 55}=3.478). The habitat specificity index of butterflies (F_{3, 38}=1.504) and true bugs (F_{3, 53}=1.153) did not differ. Analysis of the community structure similarity showed that the insect community structure of the three groups significantly differed between the reserve and farmland. There was a significant difference in the community structure of butterflies between secondary forests and artificial forests (P=0.037), and there was a significant difference in the community structure of true bugs between the reserve and secondary forests (P=0.029). There was no difference in the insect community structure of beetles (P=0.507), and only habitat type had a significant effect on the species richness of the insect community. The other ecological factors did not have a significant effect. In large-scale regional landscapes, the reserve had the greatest impact on diversity, and the habitat types were closely related to the species richness of the insect communities. Well-protected natural forests are important for maintaining the distribution and diversity of insect communities in regional landscapes.