Maize Plant-mediated Effects Of Exserohilum Turcicum On Oviposition And Feeding Behavior Of Ostrinia Furnacalis

Maize(Zea mays)is an important crop plants in the global,including China.Due to climate changes and unreasonable planting methods,the main pests and diseases of maize are still prevalent,which seriously affects the yield and quality of maize.Corn leaf blight is caused by Exserohilum turcicum,which is one of the most devastating leaf diseases of maize.Ostrinia furnacalis is one of the main insect pests that harm maize plants.The main two diseases and insect pests of maize plants can simultaneously stress maize in the natural ecosystem.As a result,the interactions between E.turcicum,Z.mays and O.furnacalis often occure,but their interactions is poorly understood.Therefore,in this study,E.turcicum,Z.mays and O.furnacalis were taken as the research objects,study on the influence of maize infected with E.turcicum on oviposition and feeding behavior of O.furnacalis,and revealing the mechanism of the regulation of oviposition and feeding behavior of O.furnacalis by E.turcicum from the perspectives of leaf volatiles,plant nutrition,and defense.The main conclusions of this study are as follows:1.E.turcicum significantly affected ovipositin and feeding behavior of O.furnacalis.O.furnacalis adults laid less eggs on maize plants colonizing by E.turcicum,including the first and second generations.At the same time,the infection of E.turcicum increased consumption of O.furnacalis larvae with the first generation for spot-free parts of diseased leaves.However,there was no significant difference between healthy leaves and spot-free parts of diseased leaves for O.furnacalis larvae with the second generation.O.furnacalis larvae with both the first and second generations avoid feeding on the spot parts of diseased leaves.2.The changes of volatiles content and color of maize leaves caused by E.turcicum may be the main factors regulating the oviposition behavior of O.furnacalis.The first generation of O.furnacalis reduced the number of eggs on maize plants infected with E.turcicum was mainly attributed to the increase in the content of(E)-2-hexenal and the decrease in the content of(E)-2-pentenal released from maize leaves induced by E.turcicum.The reason why the second generation of O.furnacalis was repelled by the maize with northern leaf blight is due to the yellowing of maize leaves was aggravated,and the contents of decanal,octanal and myristic acid released increased,and the contents of leaf alcohol decreased,as well as naphthalene and farnesol released by E.turcicum acted together.3.The nutrition and defense components of maize plants changed significantly after infecting by E.turcicum,which is the main driving factors to regulate feeding behavior of O.furnacalis.Among them,the increased content of soluble sugar in the spot-free parts of diseased leaves may enhance the consumption of the first generation of O.furnacalis to this parts.However,the increased content of flavonoids,and activity of polyphenol oxidase(PPO)and peroxidase(POD)in the spot parts of diseased leaves may reduce the feeding preference of the first and second generations of O.furnacalis to this parts.To sum up,the oviposition and feeding behavior of O.furnacalis for maize plants were changed after infecting by E.turcicum,it is mainly attributed to the change of released volatiles,nutrition and defense ability of maize plant leaves caused by E.turcicum.This finding not only provides experimental evidence for understanding the mediated effects and mechanisms of plant pathogenic on oviposition selection and feeding behavior of phytophagous insects,but also provides practical guidance for reasonably predicting the population dynamics and harm of O.furnacalis in the presence of corn leaf blight in maize plants.