| The species and abundance of insect pests and natural enemies on 75 maize varieties cultivatated in Shandong province were investigated and the resistance levels of 75 maize varieties to insect pests were identified.The ecological principles and methods were used to analyze the community characteristics of arthropods on different maize varieties.All the researches provided guidance to coordinate the relationship of maize resistance and natural enemies to control insect pests and supplied the important theoretical and practical basis for use of resistant maize varieties and safe production of maize.The main results are as follows:1.The resistance levels of 75 maize varieties to main insect pests were identified according to the aphid/borer index,finding the resistance levels of maize varieties varied in different maize varieties and their development stages.Most of maize varieties showed highest resistance to 3 species of aphids(Aphis gossypii,Rhopalosiphum padi and Rhopalosiphum maidis)and a minority of maize varieties showed highest resistance to 3species of lepidopterous borer pests(Conogethes punctiferalis,Ostrinia furnacalis and Helicoverpa armigera).“Xinfeng 388” showed highest resistance to Conogethes punctiferalis.“Ainong 001”,“Ainong 007” and “Dedi 336” showed highest resistance to Helicoverpa armigera;none of maize varieties showed highest resistance to Ostrinia furnacalis.2.The communities of arthropod on all maize varieties contained 35 species,including12 species of insect pests and 23 species of natural enemies,belonged to 23 families,7 orders,2 classes,1 phylum.The dominant species of insect pests on maize were Aphis gossypii,Rhopalosiphum padi,Rhopalosiphum maidis,Conogethes punctiferalisand Ostrinia furnacalis.The dominant species of natural enemies were Coleosoma octomaculatum,Hylyphantes graminicola,Harmonia axyridis,Propylaea japonica,Chrysoperla nipponensis and Aphelinus sp.3.The community characteristics of arthropods on 75 maize varieties were analyzed comprehensively.The 5 kinds of characteristics indexes of each arthropod community varied in different maize varieties.Ecological dominance was negatively correlated to community diversity and evenness.Maize varieties with high community diversity index had higher dominance of natural enemies and lower dominance of the main insect pests.4.The population dynamics of the main insect pests and natural enemies in the maize field were analyzied with some factors affecting the population dynamics.It was found that the populations of the insect pests and natural enemies showed differences in temporalsequence and the peak of nature enemies appeared a following relation with the insect pests obviously.Three species of aphids mainly damaged the leaves seriously at first ten days of September;Helicoverpa armigera moved and damaged in maize field earlier than Conogethes punctiferalis and Ostrinia furnacalis.Populations of Conogethes punctiferalis and Ostrinia furnacalis increased and peaked dramatically at the middle ten days of September.Conogethes punctiferalis and Ostrinia furnacalis simultanously damaged the female ears of maize after the middle ten days of September.5.Among the 75 maize varieties,the maize varieties with higher resistance tended to have higher ratio of natural enemies to insect pests,implying a compatiblity of resistance of maize with natural enemies in controlling insect pests. |
