Analysis of diamondback moth populations under hostplants stress by RAPD

Key Words： Plutella xylostella, host plants stress, population variation, RAPD

Abstract：          DNA polymorphism of the fourth, ninth, and fifteen generations’ of diamondback moth (DBM) Plutella xylotella (L.) populations, feeding on six different cruciferous host plants, was studied using the RAPDPCR technique. After repeated DNA amplification with 17 primers, electrophoretic bands were statistically analyzed with NTsys software and a genetic distance matrix and dendrogram constructed. The results indicate that the population feeding on Brassica alboglabra Bailey clustered independently on one branch and was separated from the other five populations by the largest genetic distance (0.6523-0.8246). The populations feeding on Raphanus sativus L. and B. oleracea L. clustered on one branch and the genetic distance between these was small（0.3443）. The genetic distance between populations feeding on B. chinensis L., B. juncea L. and B. parachinensis Bailey was also small and these populations also clustered on a single branch. With increasing generations the genetic differentiation of populations feeding on B.juncea L., R. sativus L. and B. oleracea L stabilized. As the generations increased, the average value, range of genetic distance between each host population and the proportion of polymorphic bands in the total number of bands enlarged. This shows that the level of population differentiation increases with generation.