Effects of rose infected by powdery midew on feeding behaviour of beet armyworm and its mechanism

It is well-known that the interactions between phytopathogenic fungi and herbivory insects on their shared host plants exist commonly. But the interaction was studied mainly under macro ecological methods in most of researches. Thus， they remain unclear whether the spacial effect exists in the interaction between fungi and insects and how to interact each other. In the present study， the inhibitory effects of rose infected by powdery mildew infection on beet armyworm， the spacial effects， and the mechanisms of inhibition were studied. The results showed that the infection of rose plants by rose powdery mildew caused the decrease of amounts of leaf area consumed by larvae of beet armyworm（from 989.1 mm 2 to 198.5 mm 2 ） ， demonstrating a significant inhibitory effect on insects. The spacial effects were found in the inhibition and the amounts of leaf area consumed gradually decreased with the increase of infection level. The changing trends of inhibitions were the same as the trends of changes of water content in rose leaf tissues caused by the infection（from 80.23% in healthy rose leaves to 60.59% in infected ones）. Therefore， the results indicated that the decrease of water content in rose leaves caused by the infection was mainly responsible for the inhibition of larvae. The results in the present study are very helpful to understand the interactions between fungi and insects and its mechanisms.