The Research Of Biodiversity Pattern And Interactions Between Natural Enemies And Pests Under Typical Black Soil Farmland Management In Northeast China

Maintaining 1.8 billion mu of arable land is listed as basic national policy,and its protection and utilization are of great strategic significance to food production and the long-term stability in China.As an important commercial grain supply area,it plays an important role in regulating grain production in Northeast China.As an important part of the ecosystem,insects above-surface-below ground have always been associated with crop yield and quality,and have long been an important factor that has plagued land use and rational planting.Due to the long-term use of a large number of pesticides,excessive fertilization and unreasonable cultivation and measures,the quality of crop field has decreased,and the biodiversity of farmland has declined,resulting in a sharp increase in the population of individual species with strong stress resistance,which seriously endangers the balance of the ecosystem,resulting in food production fell.Therefore,studying the distribution and interaction of insect diversity in farmland ecosystems can play a role in the self-regulation of ecosystems,and also help rationally develop and utilize farmland ecosystems and farmland pests,improve farmland utilization,and ultimately lead to rational land use,and it is significant in the sustainable development of agriculture.In this study,the black soil farmland has been continuously cultivated for30 years in Northeast China.A large-scale fixed monitoring plot of cropland with 400 m×400 m was constructed to monitor the spatio-temporal dynamics,distribution patterns and the interaction relationship and ecological characteristics among the insects.The absolute dominant insects on the plant and the soil indicator insects(two kinds of soil animals)are selected as the research objects.It can realize the protection and utilization of beneficial insects to control pests and maintain the stability and balance of ecosystem.The results showed that:(1)The composition of insect community structure,the distribution of trophic functional groups and diversity pattern were clarified.A total of 6085 samples of cropland insects,including 47 species of 11 orders,26 families were obtained by using the suction trap and direct observation method in the monitoring sample of cropland.There are 3 absolute dominant populations,Rhopalosiphum padi、Monolepta hieroglyphica、Lasius alienus,10 dominant populations and 34 other populations.In each functional group,the number of herbivorous insects accounts for 67.3%,which is the absolute dominant population in farmland.predatory and parasitic natural enemy insects respectively account for 8.9% and 3.9%,which is a general population in farmland;neutral insects in farmland to 19.9%,which is the dominant population in farmland.Analyzing the diversity index of groups of insects showed that the stability of insect community structure in cropland was poor,the ecological characteristics of populations changed greatly,and the natural enemy populations had no significant effect on pest control.Therefore,it is necessary to adopt a scientific farmland management model to improve farmland biodiversity and realize the protection and utilization of cultivated land.(2)Find out the interaction mechanism between dominant pests and their symbiotic and competitive insectsAphids-ants and aphids-grubs were used as two pairs of model systems.As the absolute dominant species on plants,we carry out research on the expansion of spatio-temporal co-occurrence between aphids and the symbiotic surface soil animal ants,and the above-ground and underground interaction research on plant regulation with the competitive underground soil animal grub.The results indicated that both ants and aphids showed aggregated distributions,the coincident spatio-temporal distribution and co-occurrence expansion.Grubs significantly inhibited aphids.spatial population expansion has become an important factor in biodiversity regulation in an infinite number of host plants,and each species can coordinately expansion or inhibit the population increase through interrelated species,thereby increasing the reproduction rate of this species population,and performing population reproduction.It shows that the utilization of insect diversity in corn farmland should regulate the random expansion of insect populations,and achieve the purpose of using natural enemy insects to control pests.(3)Expansion mechanism of natural enemies and pests in different land use types was revealed.Based on different land use types,shelter forests,wasteland and corn fields,the temporal dynamics and population expansion of pests and natural enemies in each habitat were investigated.The results showed that in wasteland was the largest except August.In all habitats,both pests and natural enemies tend to increase firstly and then decrease,and the peak period is different.Pests and natural enemies in corn field reached their peak in August.Most populations in wasteland and shelter forest reached their peak in July.The appearance of natural enemies is delayed after pests.In the landscape agro-ecosystem,the change of insect population in farmland changes with the change of insect population in relatively stable weed fields and shelterbelt,and the dynamic change pattern of pest populations and their natural enemies also changes.Aphids change with natural enemies with food quantity and expansion of biological populations in time and space.Therefore,in order to use natural enemies to control pest populations in farmland,it is necessary to coordinate the control of biological populations in agro-ecosystem to provide technical support for agricultural production.(4)Based on the above research,propose feasible farmland management models and land use schemes.Research on the interaction and maintenance mechanism among functional insect populations through monitoring sample plot.Propose measures to maintain farmland biodiversity and manage land protection and utilization.Reduce the distance between habitats in farmland landscape ecosystems,increase the diversity of host plants and insect populations in the habitat.Establish a rational and intensive land management model,adopt protective farming methods and land management methods,rationally plan land use methods and types,and strengthen high-standard farmland construction.Improve the quality of farmland and the agricultural ecological environment,put forward different management measures to control the pest population,optimize new measures for pest control,and formulate a set of ecological regulation technology.It provides theoretical support for food safety production in China,strengthening the protection of black land,increasing farmers’ income and realizing the development of agricultural modernization.