Genetic diversity in different populations of citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) in Tunisia, assessed by RAPD-PCR

The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) is a major invasive pest of citrus in Tunisia. In order to help the implementation of an efficient integrated management strategy, it was essential to assess the genetic diversity and population structure of the pest. For this purpose, random-amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was applied, using eight oligo-nucleotide primers, to reveal genetic variability among eight populations of P. citrella, originating from the north, center and south of Tunisia. A total of 66 RAPD markers and 33 phenotypes were generated. Inter-population polymorphism was revealed, using the percentage of polymorphic markers (62.12 %), mean number of phenotypes generated per primer (4.125) and mean genetic distance (0.199). Hierarchical analysis, using the UPGMA method, indicated that the genetic variability was influenced by the regional distribution. This pattern of population clustering was supported by Principal Coordinate Analysis (PCO). Yet, a weak correlation (0.69) was revealed between genetic and geographic distances, suggesting that climatic contrariety between the north and south of Tunisia plays a major role in the differentiation of P. citrella, leading to a restriction of gene flow between populations. Results obtained in this work show clear genetic differences, which should be considered in the development of control strategies.