Research On Population Dynamics And Community Charateristics Of Aphids And Their Natural Enemies On Maize And Resistance Of Different Maize Varieties To Aphids

Safe production of maize as the grain crop with the widest planting area in China,is closely related to the economic development of agriculture in China.Resent years,the aphids on maize occur more and more severely,effecting the growth and the yield increasing of maize and posing threat to the safe production of maize.In this study,we investigated the occurrence of three different aphids,Aphis gossypii,Rhopalosiphum maidis and Rhopalosiphum padi,and their natural enemies on summer maize in Tai’an,Shandong,China in 2021.The resistance levels of 66 maize varieties to insect pests were identified.The population dynamics,species composition,relative abundance of pest and enemy groups,dominant species and community characteristics on maize and the resistance levels to the aphids were clarified.All the research can provide reliable basis for screening the resistant maize germplasm and the green control of aphids in maize feilds.The main results are as follows:1.Clarifying the population dynamics of major aphids and their natural enemies.The population dynamics of three species of aphids（Aphis gossypii,Rh.maidis and Rh.padi）and their natural enemies were investigated in one singular maize variety field（Denghai605）.Aphis gossypii was first observed on maize and damages on leaves,peaking on 25^thAugust,followed with Rh.maidis and Rh.padi.Both aphids peaked on 22^thSeptember and synchronized in temporal sequence,with a small quantity at the seedling stage and a large quantity at the ear stage.Compared with Aphis gossypii and Rh.padi,Rh.maidis occurred in small quantity.Investigations showed that many natural enemies synchronized with those aphids in temporal sequence,reflecting a good temporal following with occurrence of the aphids.2.Analyzing the community characteristics of three species of aphids and their natural enemies in one singular maize variety field（Denghai 605）.The community of three species of aphids and their natural enemies consists of a total of24 species,including the 3 species of aphids and 21 species of natural enemies.The dominant species of aphids on maize were Aphis gossypii and Rh.padi,the dominant species of natural enemies were many predatory ones,including spiders（Coleosoma octomaculatum and Hylyphantes graminicola）and ladybugs（Harmonia axyridis and Propylaea japonica）.The diversity and evenness indices of community of aphids and their natural enemies on maize showed a trend with first rising and then decreasing.3.The identification of the resistance of maize varieties to aphids.The resistance levels of 66 maize varieties to aphids were identified according to the aphid index and the resistance levels varied in different maize varieties.Three maize varieties,Zhengdan 958,Defa 705,and Lianyan 155,exhibited high resistance to Aphis gossypii;17maize varieties showed high sensitivity to Aphis gossypii,they were Denghai 6188,Youtian738,Anyu 706,Laiyu 1819,etc.17 varieties showed high resistance to Rh.maidis,they are Dedan 5,Denghai 606,Lianyan 155,Zhengdan 958,etc;16 maize varieties showed high sensitivity to Rh.maidis,namely Dedan 123,Defa 106,Haohan 1588,Defa 705,etc.24 maize varieties with high resistance to Rh.padi were Yuqing 358,Zhengdan 958,Zhengyuan Yu432,Haohan 1585,etc;there were 13 maize varieties with high sensitivity,namely Ningyan678,Jingke 999,Denghai 511,Luhe No.1,and so on.4.Based on the relationships of predation and parasitism between aphid natural enemies and aphids investigated in maize fields,different food webs of arthropod communities of aphids and their natural enemies on maize were constructed and a preliminary analysis of the aphid and natural enemy relationships was carried out.