Distribution characteristics of insect diversity in long-term fixed monitoring plots in Northeast China

The spatial patterns of field arthropod communities are an essential part of ecology and can provide fundamental data regarding field ecological processes and reveal the mechanism of ecosystem biodiversity maintenance. This study investigated the spatial distribution pattern of field insect communities to detect the spatial relationships between insect communities in farmland. The study site was located at the Dehui Agro-ecological Experimental Station of Black Soil, Jilin, China. Insect communities and environmental factors were sampled at 121 uniformly distributed points in a 400 × 400 m plot in August, September, and October 2015. The analysis revealed that insect communities from June to October demonstrated significant spatial correlation, and 6085 samples of 47 species and 47 families in 11 orders were collected from the insect community in the farmland. The farmland insect community structure changes and dynamic changes of nutritional function groups occur with time. According to the 400 x 400 m plot, the diversity of farmland insect communities and functional groups is maintained at a relatively high and stable level. In this study, a total of 6085 samples of corn farmland insects were obtained using the fluke method and direct observation method, including 11 orders, 26 families and 47 species, 4 absolute dominant populations, 6 main dominant populations, and 37 other populations. These studies can provide help for pest control in the spring corn area of Northeast China.

continue to penetrate ecology [5]. However, they are not consistent regarding various 57 formulas and the relationship between diversity and richness, stability, and other factors. 58 This is consistent with the diversity distribution of mayfly [6]. Because the functions of integrated pest management provided a scientific basis [7,8,9,10].

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This research will carry out long-term systematic monitoring of corn farmland. On the 74 one hand, it will reveal the mechanism of insect population biodiversity in farmland, the 75 existence of farmland biodiversity allows natural control of population numbers among 76 organisms, and on the other hand, it will provide technical support for pest control in spring 77 corn farmland in Northeast China.

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This paper researched a novel the structure, function and dynamics of farmland 79 arthropod communities, to explore the interrelationships between species within the 80 community,. In particular, the internal mechanism of mutual restraint is researched which can come true the occurrence and development of pests, pest population forecasting and 82 optimal control. The research of this paper is significant for the eco-control research.

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The aim of the this research is to answer the following questions about a long-term with dry and cold winters and warm and humid summers. The annual average temperature 97 is 4.4 °C, and the average annual rainfall is 520 mm, of which 80% of the rainfall is 98 concentrated in July and August. Dehui has 214,000 hm 2 of cultivated land, of which 99 163,000 hm 2 is corn, accounting for 76.2% of the total cultivated land area [11,12].     to the laboratory to identify and classify the captured insects [13].  The coefficient of variation reflects the degree of dispersion or difference of data, 142 namely, the distribution of data, reflecting the heterogeneous characteristics of animal data.    In formulas (1) to (6): N is the total number of individuals in the species; S is the number 174 of species in the community; and ni is the number of individuals in the i-th species [12].

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The Holotrichia oblita Faldermann chafer accounted for nearly 50% of the 257 phytophagous insects and 63% in August. The herbivorous insects accounted for nearly 258 80%, demonstrating that harmful insects have an absolute advantage in the entire farmland.

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The corn grasshopper aphid and the two-spotted tarsaled beetle accounted for 83% of the 260 herbivorous insects. Therefore, it can be inferred that in the vigorous period of corn growth, in farmland insect communities [14,15]. The more unevenly distributed the species, the more prominent the dominant population is. interference differences [17] .

Farmland insect community biodiversity distribution
In 2010, Christoph believed that the diversity of species was the key to biodiversity.
It not only embodied the complex relationship between organisms and the environment but also embodied the richness of biological resources [18]. Diversity not only reflects the richness and variability of the community but also reflects the relationship between different natural geographic conditions and community development to varying degrees.
One of the characteristics of the stability of biological communities is high diversity. It is one of the central topics of modern ecology research. The farmland ecosystem is an ecosystem under human interference. The diversity of farmland insect and animal communities is not only related to the number of species, population ratio, interspecies relationships, and the complexity of the food web but also closely related to the growth and development stages of corn and human factors [19] . Table 3 demonstrates that the structural trends of farmland diversity are quite unstable because the farmland has a single planting structure, all of which are corn. This only provides a place for insects that feed on corn, and the structure of species biodiversity is simple. Therefore, maize farmland is prone to large-scale outbreaks of pests, and the population of certain dominant species is high, which leads to the instability of the community structure and the decline of diversity. In general, the management level of farmland is relatively high, and the occurrence of pests has been controlled within a certain range. Therefore, Jangid (2011) put forward that the diversity of farmland insect communities and functional groups was maintained at a relatively high and relatively stable level [20]. Table 3 Biodiversity characteristics of farmland insect community functional groups.