Resistance Of Maize Varieties To Insect Pests And Analysis Of Arthropod Comminity Diversity On Maize Varieties

The species and their abundance of pests and natural enemies on 50 maize varieties in Tai’an city of Shandong province were investigated.The borer/aphid index based on the abundance of the main insect pests were used to identify the resistance of 50 maize varieties to the main insect pests.The population dynamics,species composition and relative abundance of the total insect pests and natural enemies on 50 maize varieties were analyzed,and the dominant species of insect pests and natural enemies and the characters of arthropod communities on 50 maize varieties were also explored.The main results were as follows:1.The resistance levels of 50 maize varieties to main insect pests were identified according to the borer/aphid index.It was found that there were differences in the resistance levels among different maize varieties,and also at different growth stages of the same maize variety.There were no maize varieties with highest resistance to 3 species of lepidopteran borer pests（Conogethes punctiferalis,Ostrinia furnacalis,Helicoverpa armigera）and aphids（Aphis gossypii,Rhopalosiphum maidis and Rhopalosiphum padi）.Yuqing 358 have high resistance to 3 species of lepidopteran borer pests;Xinrui 37,Qidan 805,Zhengdan 958,Xinrui 57,Tomorrow 695 and Luxing 702 were highly resistant to Rhopalosiphum maidis and Rhopalosiphum padi.No varieties showed high resistance to the three species of aphids.The resistance of maize varieties to insect pests varied in different growth stages,for example,from the silk stage to the mature stage,the resistance of Tomorrow 695 to Conogethes punctiferalis and Ostrinia furnacalis changed from high resistance to high susceptibility,while the resistance to Helicoverpa armigera changed from high susceptibility to high resistance.The resistance of four maize cultivars,such as Jinhai 2010,to Rhopalosiphum maidis and Rhopalosiphum padi had changed from high resistance to high susceptibility.The resistance of maize varieties to lepidopteran borer pests and aphids was different,and the number of varieties resistant to aphids was more than that to lepidopteran borer pests,indicating that the resistance of most varieties to aphids was better than that to lepidopteran borer pests.2.The species composition of the arthropod community on all maize varieties mainly included leaf-chewing insects,bore insects,sap-sucking pests and their natural enemies.There were 46 species of arthropods belonging to 29 families,7 orders,and 2 classes.Among them,there were 18 species of pests,accounting for 39.13%of the total,mainly including lepidopteran pests and aphids and 28 species of natural enemies,accounting for 60.86%of the total,mainly including spiders,ladybugs,lacewing,predacous bugs,parasitic wasps and syrphids.In the whole community,aphids and lepidopteran larvae occurred in large quantities;and among the natural enemies,the abundance of the spiders were dominant.The dominant species of aphids were Rhopalosiphum padi and Aphis gossypii,the dominant species of ear borer were Ostrinia furnacalis,and the dominant species of natural enemies were Hylyphantes graminicola,Coleosoma octomaculatum,Harmonia axyridis,Propylaea japonica,and Chrysoperla nipponensis.3.The population dynamics of main pests and natural enemies on 50 maize varieties were analyzed.it was found that Spodoptera exigua,a leaf-chewer,peaked in late July.The three ear-borers,Helicoverpa armigera,Ostrinia furnacalis and Conogethes punctiferalis,mainly occurred from mid August to late September.Helicoverpa armigera peaked on August15^th;Ostrinia furnacalis peaked on September 3^rdand September 23^rd,respectively;Conogethes punctiferalis has rosen from August 24^thto October 2^nd.Aphid pests seriously occurred from early September to late September,and peaked on September 23^rd.The occurrence peaks of natural enemies coincided with the occurrence of pests,indicating that the natural enemies followed the pests well to some certain extent.4.The characteristics of arthropod community on 50 maize varieties were analyzed.It was found that the maize varieties with higher resistance to aphid had higher dominance of natural enemies and lower dominance of aphids.The results showed that there was a certain correlation between maize variety resistance and community diversity,showing that the maize resistance to pests and the natural enemies had a combined control effect on pests.