Effects Of Growth Stage Of Host Plant And Endosymbiont Infection Of Arsenophonus On The Population Size And Distribution Of Cotton Aphid

Cotton aphids have a wide range of hosts and it is the main pest on cotton and melon crops.Existing researches show that the population of cotton aphid has formed a significant differentiation of the host utilization ability,and there are cotton-specialized and cucurbit-specialized all over the world.Cotton-specialized aphid can make good use of the host cotton plants,and can also use zucchini and cowpea to host plants,but can not use cucumber host.At the same time,the cucurbit-specialized aphid can not make good use of cotton host.The nutrients and secondary substances of different host plants have different types and contents,and there are differences between the same plants of different period,therefore,it is worthwhile to study whether there are differences in the ability of the host to be used in different growth periods.In addition,aphids have different sy1biotic bacteria,and it is not clear whether the infection of secondary symbiotic bacteria can affect the host utilization of cotton aphid,thus promoting the formation of host speciation.Therefore,in this study,different genotype cotton aphids from infected and non-infected Arsenophonus were studied,the population dynamics and spatial distribution of cotton,cucumber,zucchini and cowpea in different growth stages were studied,the results of the study will clarify the influence of symbiotic bacteria infection and plant growth period on the utilization of cotton aphids,thus promoting the mechanism of aphid host specificity.The following results were obtained:Different genotype cotton aphids were transferred to cotton,cucumbers,zucchini and cowpeas in different growth stages of cotton aphid,which were natural infected by Arsenophonus,non-infected by Arsenophonus strains and antibiotics,the population density of cotton aphid and the number of cotton aphid in different parts were investigated in different days after transfer,the results showed that the number of cotton aphid population was affected by the species of host plant,the growth period,the genotype of cotton aphid and the infection of the Arsenophonus.The number of cotton aphid in seedling was higher than that of old cotton.The number of cotton aphid in the flowering cucumber was higher than that on the seedling stage,however,the six genotype cotton aphids tested were not suitable for the cucumber host.All of them died around the 6th day after transfer.The population quantity of cotton aphid was higher than that of flowering period and late flower in seedling stage.The population of cotton aphid was higher than that of seedling and flowering cowpea in late flowering.The infection Arsenophonus and reduces the ability of some genotype cotton aphid to make use of old cotton plants,zucchini and cowpea,the number of population after after removing Arsenophonus was significantly increased.It will also improve the utilization ability of some genotype cotton aphid for seedling cotton and flowering cowpea.At the same time,it has no effect on the ability of some genotype cotton aphid to use cotton,zucchini and cowpea.The infection Arsenophonus will not affect the utilization ability of different groups of cotton aphid to cucumber host.By investigation of aphis gossypii in upper,middle and lower parts number distribution on the blade,the method of stUdy the host plant species,growth period,Arsenophonus infection and aphis gossypii genotype influence on population distribution or feeding areas,the results showed that the distribution of cotton aphid populations in different parts of the host plant was affected by the species of host plants,the growth period,the genotype of the cotton aphid and the infection of Arsenophonus.The cotton aphid was mainly distributed on the upper leaves in the seedling stage cotton,and the old plants were mainly distributed in the middle and lower leaves.In the seedling stage of the zucchini,it is mainly distributed in the upper and lower leaves,the flowering stage is mainly distributed in the upper and middle leaves,and the late flowering stage are mainly distributed in the upper and middle leaves.At the seedling stage of cowpea,the main distribution of the leaves on the lower part of the plant,the mainly distributed in the middle leaves during the flowering period,and the late flowering stage were mainly distributed in the middle leaves.And the distribution of different genotypes varies.The effect of Arsenophonus on different genotype cotton aphid was different.Some genotype cotton aphids of infected Arsenophonus were mainly distributed in the middle leaves of old cotton plants,in addition,the distribution site after the removal of Arsenophonus was transferred to the upper leaves.Some genotypes of infected Arsenophonus can be distributed on each leaf in the seedling stage zucchini,and the main distribution was in the upper and middle leaves after the removal of Arsenophonus.Some genotypes of the infected Arsenophonus were mainly distributed in the middle leaves of the late flowering cowpea,the main distribution in the middle and lower leaves was the removal of the Arsenophonus.The infection of the Arsenophonus causes the change of the distribution of some genotype cotton aphid on the host plant.