Genetic Relationships Among Species In Grasshopper From Shanxi Province, China

The Locust of Arcypteridae is a large insect group of Acridoidea that can be found in various ecological habitats. The insects have different ecotypes and geographic populations as a result of feeding habits and the adaptations to each environment. Due to the extended high temperature, long-lasting drought and the consequent alternations in locust breeding environment, the destructive outbreaks of locust had been increasing in China, which seriously threaten the agriculture production and destroy entironment.The Random Amplified Polymorphic DNA (RAPD) technique is a method for examining the DNA polymorphism developed in 1990s. Based on PCR technology it uses the single-stranded oligonucleotide of random sequence as primer to amplify the genomic DNA. The method is favored because it can examine a large amount of loci at the genome by using many primers. Microsatellite primer PCR analysis (SSRP-PCR) uses published VNTR core sequences as primers in PCR, no prior knowledge of target sequence is required. In addition, studies have indicated that SSRP-PCR can produce more reliable and reproducible bands because of the longer primers and more stringent annealing temperatures. Now it has been applied to examine the variability among species, compare the genetic variation within and among populations.The molecular phylogenetic relationships of four species of Chorthippus Fieber including C. albonemus Cheng et Tu, C. hsiai Cheng et Tu, C. fallaw (Zub.) and C. hammarstroemi (Mir.) were studied with Random amplified polymorphic DNA (RAPD) and Microsatellite primer PCR analysis (SSRP-PCR). Moreover, the genetic divergence of two natural species of Euchorthippus unicoloe (Ikonn) and Euchorthippus cheui Hsia was studied with RAPD method.131 clear and stable bands of 98 grasshopper individuals of Chorthippus with molecular weight ranging from 250 to 1800bp revealed on the electropherogram amplified by 9 primers, Shannon's index showed hightergenetic diversity (0.2542) within C.fallax (Zub.) and lower genetic diversity (0.1911) within C. albonemus Cheng et Tu. The dendrogram based on Nei's genetic distance of RAPD and SSRP-PCR markers was constructed with Neighbor-Joining methods. The clustering followed the order, first the individuals within a population, then the different population of the same species, later the species of the same subgenus, and finally the species of the same genus. The four species fell into 2 branches, C. albonemus Cheng et Tu and C. hsiai Cheng et Tu were clustered into one branch, while C. fallax (Zub.) and C. hammarstroemi (Mir.) were grouped to another branch. Then two branches were clustered. The results of dendrogram were consistent with the previous conclusion of morphologic classification.107 clear and stable bands of 29 grasshopper of Euchorthippus individuals revealed on the electropherogram amplified by lOprimers. Nei's index and a genetic distance matrix were analyzed. The results showed genetic differentiation coefficient estimated by Nei's index was 0.3839, that is, 61.61% of the variation occurred within species and 38.39% of the variation existed among species. The dendrograms based on Nei's genetic distance of RAPD markers were constructed using NJ and UPGMA indicating high similarities within species. The results achieved by the method of RAPD revealed the genetic pattern of variation.Comparisons of molecular markers for measuring genetic diversity have been carried out in the way of Genetic relationships. A better understanding of the effectiveness of the different molecular markers is considered a priority step toward locust germplasm characterisation and classification. It is suggested that RAPD and SSRP-PCR analysis is useful as molecular marker, for grasshoppers in phylogenetic reconstruction at the species level.