Effects Of Citrus Tristeza Virus On The Feeding Behavior Of Citrus Aphid Using Electrical Penetration Graph

Citrus tristeza caused by Citrus tristeza virus(CTV)is one of the most important economically diseases of citrus and spread through Toxoptera citricida(Kirkaldy),Aphis gossypii Glover,Aphis citricola Van der Goot in the field.The vector aphid and citrus tristeza widely distributed in the world and made serious threat to the citrus industry.The vector transmission of plant virus involving insect,host plants and plant pathogenic virus infection,is a very complex process.Virus had direct or indirect influence on insect and plant,and affected the spread of the virus.To explore interactions among CTV,citrus and citrus aphid,this study monitored feeding behavior of alate and apterae of T.citricida,A.gossypii and A.citricola on the health and CTV4-infection citrus by electrical penetration graph(EPG)to analysis the influence of citrus tristeza on feeding behavior of citrus aphid.The results are as follows:1 Influence of CTV on the feeding behavior of alate and apterae of Toxoptera citricidaThe detailed feeding behaviors of alate and apterae of T.citricida were monitored by EPG(electrical ponetration graph)with feeding behaviors in uninfected citrus plant as the control.The results showed that:(a)Total duration of np of apterae of T.citricida were significantly lower than that of their alate's.(b)For apterae of T.citricida during no phloematic phase,the number of of probes and the number of pd in CTV-infected plants were significantly higher than those of healthy plants,but the total times of probes was significantly shorter than that of healthy plants,and the total duration time of C and np was significantly higher than that in healthy plants.The phloem parameters include the E1 associated with saliva secretion and the E2 parameters associated with the vegetable juice.The parameters between the number and total duration of E1 and the number of E2 on the healthy plants were not different from those in the CTV-infected plants,but the total duration time of E2 was significantly different,and 295.06±9.99 min on the healthy plants was higher than231.30±21.78 min on the CTV-infected plants,and the average duration time of E2 was significantly higher than that of CTV-infected plants.(c)Compared with healthy plants,the ratio of E2 to the total time in the diseased plants decreased by 84.51% on the healthy plants and 69.11% on the diseased plants,The difference was very significant.The results indicated that the effect of alate and apterae of T.citricida on the CTV-infected plants was similar,and the apterae aphid was more efficient than the alate's.The susceptible plant could reduce the effect of the host on T.citricida,and the apterae of T.citricida were preferred to feed on the healthy plants,while the alate of T.citricida had no significant difference in the feeding of healthy plants and CTV-infected plants.2 Influence of CTV on the feeding behavior of alate and apterae of Aphis gossypiiThe detailed feeding behaviors of alate and apterae of A.gossypii were monitored by EPG with feeding behaviors in uninfected citrus plant as the control.The results showed that:(a)The number of of probes and the total duration time of np of apterae was significantly higher than that of alate in the healthy plants in the non-phloem stage,but the total duration time of probes was the opposite,and the number of probes after the first E was significantly larger than that of wingless type.The number of probes of A.gossypii was 19.16 times,which was significantly higher than that of wingless type as 9.38 times.The total duration time of np and C,the number of pd on the CTV-infected plants were significantly greater than those of the apterae type.The number of probes in A.gossypii alate type on the CTV-infected plants was significantly greater than that of apterae ones.Other non-phloem parameters were not significant differences.(b)The CTV-infected plants had no significant effect on the 17 parameters of non phloem and phloem.(c)There was no significant difference in the proportion of feeding behavior parameters between the alate and apterae species on the healthy plants and CTV plants.The results indicated that there was no significant difference in alate and apterae of A.gossypii the healthy and susceptible plants.However,the feeding efficience of the alatewas was lower compared with the apterae aphid.3 Influence of CTV on the feeding behavior of alate and apterae of Aphis citricolaThe detailed feeding behaviors of alate and apterae of A.citricola weremonitored by EPG with feeding behaviors in uninfected citrus plant as the control.The results showed that:(a)On the healthy plants,the number of probes and the number of probes after the first E of the alate of A.Citricola at the non-phloem stage was significantly higher than that of the apterae type,and the number of probes before the first E was the same.The number of probes and the number of probes before the first E of alate in the CTV-infected plants were significantly higher than those of the apterae type.Other non-phloem parameters were not significant differences.(b)The number of probes of A.citricola in the CTV-infected plants was significantly larger than that of healthy plants before the first E wave of susceptible plants.(c)There was no significant difference in the proportion of the waveforms of feeding behavior between the alate and apterae species on healthy plants and CTV-infected plants.The results suggented that the wingless type had the advantage of feeding behavior on the healthy plants and susceptible plants compared with the healthy plants,the number of probes before the first E of A.citricola was less than susceptible plants.Maybe A.citricola wingless type in the susceptible plants need to be stabbed several times to reach the phloem.