Preference And Feeding Behaviors Of Asian Citrus Psyllids On Different Citrus Varieties

The Asian citrus psyllid(Diaphorina citri Kuwayama,ACP)is one of the most severe insect pests in the world.The nymphs cause wilting in citrus young shoots and adults transmit the Candidatus Liberibacter asiaticus(Clas).Huanglongbing disease(HLB)around in colony,thus threaten the development of the citrus industry.Nowadays,the major strategy to control psyllids is spraying the chemical pesticides.However,it resulted in the rapid development of the insecticide resistance in this insect pest.Guangxi is leading the citrus industry in terms of planting area and citrus yield.Seeking for the maximum value,the growers would plant different varieties of their choice.Therefore,the major varieties planted in Guangxi include C.reticulata Shatangju Tangerine,Hybrids Orah,and C.grandis Shatianyou.It has been documented that ACP showed quite different preference to various varieties,which has different degrees infected HLB.In the present study,we analyzed the preference of psyllids to twelve citrus varieties widely planted in Guangxi by either laboratory choice test or field survey.Furthermore,the feeding behaviors of the Clas infected and uninfected psyllids on different Citrus varieties were tested by using Electrical penetration graph(EPG).Our results assessed the risk of Clas infection on the commonly planted varieties and provided a guide for the selection of local citrus varieties in Guangxi.The major results are as follows:1.According to the choice test experiments in lab,the psyllids showed significant difference on the preference between C.reticulata Xingjin and C.reticulata Gonggan,which belong to the same citrus genus.The selection rate in C.reticulata Gonggan(86.53%)was significantly higher than C.reticulata Xingjin(13.47%)in first 24 hours.Similar behavior was found t in the dynamic survey in the net room.In addition,the 12 varieties were ranked into four categories by using the method of systematic clustering according to the numbers of attracted ACP by each variety.Among them,C.reticulata Shatangju Tangerine and C.grandis Guiyou No.1 are ranked as top sensitive host plants for ACP(they attracted an average of 40.63 and 43.13 psyllids,respectively).C.reticulata Liucheng Tangerine,C.grandis Shatianyou,Hybrids Orah,C.sinensis Algeria Valencia Orange are rank as the second sensitive hosts;C.sinensis Hongrouqicheng,C.sinensis Newhall,Hybrids Murcoot,C.sinensis Frost Orange,C.reticulata Gonggan are rank as the tired sensitive hosts;C.reticulata Xingjin attracted an average of 5.88 psyllids during the survey,it is ranked as the insensitive hosts.2.According to the behavior experiment of ACP on C.reticulata Xingjin and C.reticulata Gonggan,the feeding process of the psyllids can be divided into three phases:(1)range search phase,the psyllids were searched continuously,the residence time was less than 10 min.(2)prick detection phase,the psyllids attempted to feeding,the residence time was 30 min – 1 h.(3)residential ingestion phase,the psyllids were fed long time,the residence time was more than 2 h.Meanwhile,the Clas infection frequency of the infected and uninfected psyllids feeding on C.reticulata Xingjin were significantly different from C.reticulata Xingjin.The time they spent in prick detection phase on C.reticulata Gonggan were higher than on C.reticulata Xingjin.Furthermore,the feeding duration by the Clas infected psyllids were significantly different from the uninfected in residential ingestion phase on C.reticulata Xingjin.According to the measurement by EPG,the wave E1 duration of psyllids feeding on C.reticulata Gonggan was higher than C.reticulata Xingjin.Meanwhile,the wave G duration of the Clas infected psyllids was significantly higher than the uninfected.The results showed that both the feeding duration and the feeding frequency of the Clas infected psyllids were higher than the uninfected.Furthermore,the feeding duration spent by the psyllids on C.reticulata Gonggan was significantly higher than C.reticulata Gonggan.