Analysis of population genetic structure of two closely related tortricid species of economic importance on macadamias and litchis in South Africa.

摘要

The macadamia nut borer Thaumatotibia (Cryptophlebia) batrachopa and the litchi moth Cryptophlebia peltastica are Afrotropical species causing extensive damage to cultivated macadamias and litchis in the northernmost provinces in South Africa. Cryptophlebia peltastica also occurs as natural populations throughout the country. To analyse the population genetic structure of the two species, amplified fragment length polymorphism analysis was conducted. Patterns of genetic diversity in C. peltastica populations in the Mpumalanga province, where the species is controlled, were compared with those in the Western Cape, where populations occur under natural conditions. Gene diversity was high within T. batrachopa populations (H=0.2219) with significant genetic differentiation among populations (Gst=0.358). Cluster analysis showed that geographical populations were closely related and extensive divergence was found over local scales. Similar to that of T. batrachopa, genetic diversity and population differentiation was high within both C. peltastica Mpumalanga and Western Cape populations (H=0.1906 and 0.1687 and Gst=0.4124 and 0.3799, respectively). It is suggested that the population genetic structure of both species is influenced by their limited ability to disperse. In addition, chemical control of C. peltastica in the Mpumalanga province has not succeeded in reducing the population size, but the C. peltastica population subdivision in the Western Cape may be influenced by the limited distribution of host plants in this region..