| The invasive insect pest,Hyphantria cunea(Drury),was from America and has spread through many countries and areas in the world.Due to omnivorous habit,large appetite,large fecundity,broadly infectious approaches,it make the pest cause serious damage to city landscape and agricultural production.In China,the invasive pest has caused heavy economic and environmental damage in some provinces and autonomous regions.Now,morphological characteristics,the life history,occurrence and the control methods on the fall webworm have had some reports from domestic and foreign scholars.However,the feeding behaviors on the larvae have not been studied.The dissertation mainly conducted two aspect studies:firstly,we observed and recorded behavior types and activity rhythms of the invasive insect,the aim is to determine its larvae activity regularity.Secondly,we designed 5 groups experiments to study and confirm the characteristics of feeding selection and feeding preference grades.This study can provide the theoretical basis and decision support for effectively control the spread of the insect,the design of urban green planning programs.In addition,it will lay the initial foundation for the futher study on the behavioral ecology of the invasive insect.The main results are as follows:1.behavior types and activity rhythm:(1) 10 behavior types including foraging,feeding, walking,resting,communication,fighting,observing,cleaning,defecation,extruding filaments and forming a web which is the most complex and unique behavior type for the insect.(2) characteristics with which larvae feed on leaves.Low instar larvae feed on the mesophyll in the back of leaf,while higher instar larvae can eat all the part except for the main vein and the petiole,four kinds of leaves remaining formations were found including remains just in the shaded of leaf,reticular,leaf with holes,indentation.(3) observation results from 24-hour feeding cycle show that the resting behavior type accounted for the largest proportion in the all acts,followed by feeding behavior,and the proportion of the act taking part in for forming net is the least.Feeding activities have some rhythm and are correlated with the time and temperature. The feeding rythem is special obvious in the cycle of the day and night.The activities frequency in the day is remarkably higher than that of night the activity peak and the lowest frequency occour in the fixed time in a day.The peak period of time of 3th instar larve occour in the 12:30 to 13:30,and 4th instar larvae is in the 11:30 to 12:30.the lowest activities frequency of 3th instar larvae is in the 20:30 to 21:30,and 4th insatr larve is in the 23- 30to0- 30.(4) the proportion of feeding behavior and food intake quantity from higher instar larvae are all much higher than that of low instar larvae,their behaviors are obviously different with different feeding rhythm.2.feeding selection of the Hyphantria cunea:(1) the experiments show that feeding of Hyphantria cunea has the selective preference to different plant species,and its selection is complex and is affected by all kinds of factors including plant species,migration of larve, intraspecies competition,randomicity of feeding selection,et al.Therefore,under different experimental conditions its feeding selection is different.(2) according to the results from 5 group experiments,we found that the non-selection experiment has less random and its results are more reliable.(3) according to integrated analysis on feeding preference of the Hyphantria cunea,we reclassify 34 plant species into the three grades including high-preference, middle-preference and low-preference.The ten plants from high-preference grade for Hyphantria cunea are Lonicera maackii,Mulberry,Cercis chinensis,David peach,Clove, Fraxinus chinensis,Apricot,Apples,Paulownia and Winter jasmine. |
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