Studies On The Population Diversity Of Aphids Using Microsatellite Marker

Aphids are a great group of Homopotera. There are four thousands species in the world and a few of aphids are pests of crops ,cottons, vegetables, oil plants, fruit trees, forest, herbal medicine, pasture and so on. Cotton aphid, some kinds of wheat aphids and green peach aphid can cause serious economic losses, and can spread manifold plant virus disease. Therefore, the aphid not only is an important member of biology diversity, but also is an important defended object of agriculture and forest. It is very necessary to cany out the basic research of aphids.Microsatellite DNA, the simple tandem repeat sequence (or simple tandem repeat sequence polymorphism), is a kind of repeat sequence in the genome DNA, whose length is less than 10bp. It spreads all over the genome of eukaryotic genomes .Its length depends on the number of repeat unit. We do not know about its function, and think that it is concerned with gene recombination leading to genetic variation. Because of its hypervariability, neutrality, co-dominance, ubiquity and especially its good polymorphism, sensitivity, microsatellite DNA is becoming preferred molecular marker for strain identification, population genetic studies, kinship analysis and mapping purpose as well as for linkage analysis, gene diagonose of transmissibility disease. It has already been an important method of molecular genetic study.The PCR technique with microsatellite primers,33.5 core sequence,(GATA)4 and (CAC)s were used to analyze the DNA polymorphism in different geographic population of green peach aphid, com leaf aphid, cowpea aphid, pine aphid, cabbage aphid and Chinese gall aphid. According to the amplified results, we can discuss the variation of population genetic arised from the changes of georgraphic conditions . The results were following:(1) The studies on genetic diversity of aphids using microsatellite primers showed that there were stabilities.(2) There were a lot of bands in the results of corn leaf aphid, cowpea aphid , pine aphid and so on, using the micrpsatellite primer 33.5 core sequence. The results also showed that the microsatellite primer, 33.5 core sequence, was a ubiquitous primer. But the microsatellite primers, (GATA)4 and (CAC)s were primers with strong speciality, because of few or none of band.(3) The studies of green peach aphid suggested that altitude and host plant could affect the genetic structure of different populations. But the data available was limited and conclusions couldn't be drawn.(4) The studies of individuals within corn leaf aphid in the same host plants but different regions showed that: the variation among populations of similar circumstances is less than the variation between populations of different circumstance. The result suggested that: the changes of circumstance can influence the genetic structure.(5) The result of Chinese gall aphid showed that: there are few differences among individuals. There were similarity in the other aphids.