Color And Genetic Diversity Among Nature Populations Of Aphis Gossypii Glove

Cotton aphid, Aphis gossipii (Glover) (Hemoptera: Aphididae) is one of the most important pest to various plant, and also an efficient vector of several plant viruses.The powerful hetergeny for population differentiation and genetic variation strength its adaptability to variable ecosystems, and also are the intra-factor for its outbreak. Therefore, it is the core for IMP research. This study combined the population ecology with molecular biology. From morphological characters, the body color differentiation and the genetic marker (RAPD-PCR) studied the cotton aphid in Henan.The fourteen morphological characters of the cotton aphids on three winter hosts,a summer host plant were studied. The results showed that the diversity wasntconspicuous of minimum width of proximal part of siphunculus, length of cauda andlength of longest hair on eighth abdominal tergite. Cluster analysis indicated that themorphological differences between samples from winter host Punica granatum and samplesfrom cotton seedling or between samples from winter host Zanthoxylum simulans and samplesfrom cotton in summer were smaller. But the population differentiation presented significantlybetween the aphids on cotton and winter host Hibiscus syriacus. It was assumed that thepopulation sources on cotton might come mainly from Punica granatum and Zanthoxylumsimulans instead of Hibiscus syriacus.Experiments were carried out to study the color differentiation in different periods of Aphis gossypii from Hibiscus syriacus, Punica granatum, Zanthoxylumsimulans and cotton plants. Results showed that the cotton aphis have yellow and green individuality. On the Hibiscus syriacus, Punica granatum, Zanthoxylum simulans, the green individuality occupies dominant position in early spring ,the yellow individuality is occupying dominant position from later spring to early summer, the green individuality is occupying dominant position from later summer to early autumn. From May to June the yellow individuality occupies dominant position on the cotton plant, its proportion is similar to that of the migratory Aphis on the winter host plants. Under the different temperature (20℃, 24℃, 27℃), the yellow and the green individuality ywere reared continuousl, investigated the color differentiation in different temperature, the results showed that the color differentiation of the Aphis gossypii Glover is close relevant to the temperature. Yellow fundatrix were collected, reared under the different conditions, The offsprings body color of yellow fundatrix were unchanged.lt showed that there are two yellow individualities in nature. Perhaps the reason is their background of inheritance is different.The results of RAPD-PCR showed that the genetic differentiation among different host populations were only at population level but had not achieved the subspecies level. Moreover, according to the analysis of Nei's genetic distance (D), it was assumed that the population sources on cotton might come mainly from Punica granatum and Zanthoxylum simulans instead of Hibiscus syriacus. The analysis of similarity index showed that the differentiation among three overwinter host populations were at low levels,but in high level differentiation appeared between populations from overwinter host populations and from the cotton.