Genetic diversity of melon aphids Aphis gossypii

Despite increasing evidence that landscape features strongly influence the abundance and dispersal of insect populations, landscape structure has seldom been explicitly linked to genetic structure. We conducted a genetics study of the melon aphid, Aphis gossypii, in two counties of Beijing, China using samples from watermelon during spring migration. We performed restriction-site associated DNA-sequencing (2b-RAD) analyses on aphid and genetic structure analyses, and tested the hypothesis that landscape features can affect the genetic diversity. Our results showed low genetic diversity among 9 populations. There was a moderate level of genetic differentiation among the populations. Pairwise Fst values between the populations ranged from -0.042 to 0.310. Higher genetic diversity populations had more polymorphic loci than lower ones. Results of AMOVA and structure analysis indicated that populations should be clustered depending on their genetic diversity (high and low). Geographic distance and genetic distance were not significantly associated, indicating that geographic location was not a barrier to migration. The genetic diversity (expected heterozygerty He and observed heterozygerty Ho) was significantly associated with landscape features. Although difference in parameters between predicting models of He and Ho, the Grassland were both significantly positive at the radius of 2 km scale; the Garden including perennial trees were both significantly negative at the radius of 0.5 km scale. This study contributes to our understanding of the genetic variation of aphids in agricultural landscapes.