NARDI FUNDULEA, ROMANIA ROMANIAN AGRICULTURAL RESEARCH, NO. 30, 2013 www.incda-fundulea.ro Print ISSN 1222-4227; Online ISSN 2067-5720 Received 16 August 2012; accepted 22 January 2013. First online: 9 February 2013. DII 2067-5720 RAR-215 GENETIC STRUCTURE OF APHIS FABAE SCOPOLI (HEMIPTERA, APHIDIDAE) IN TUNISIA, INFERRED FROM RAPD MARKERS Balkis BpML 1* , Dhia Bouktila 2* , Maha Mezghani-Khemakhem 1 , Sonia Bouhachem-Boukhris 3 , Mohamed Makni 1 & Hanem Makni 4 1 Unit of Research on the Genetics of Crop Insect Pests (GIRC), Faculty of Sciences of Tunis, University of Tunis El-Manar, Tunisia. 2 Unit of Research on the Genetics of Crop Insect Pests (GIRC), Faculty of Sciences of Tunis, University of Tunis El-Manar, Tunisia/Higher Institute of BiotechQRORJ\ RI %pMD 8QLYHUVLW\ RI -HQGRXED 7XQLVLD 3 National Institute of Agronomic Research of Tunisia (INRAT), Laboratory of Plant Protection, Section of Entomology, Tunisia. 4 Unit of Research on the Genetics of Crop Insect Pests (GIRC), Faculty of Sciences of Tunis, University of Tunis El-Manar, Tunisia/Higher Institute of Animation for Youth and Culture, University of Tunis, Tunisia. Corresponding author. E-mail: dhia_bouktila2000@yahoo.fr * The two first authors have contributed equally to this work. ABSTRACT Aphis fabae is a common polyphagous aphid represented by a complex of heteroecious holocyclic subspecies, using a wide range of secondary host plant species. In this study, we used Randomly Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) to assess the genetic diversity and analyse the genetic structure of three subspecies from this complex, namely A. f. fabae, A. f. solanella and A. f. cirsiiacanthoidis, collected from 4 locations in the North and South of Tunisia. Using 108 aphid samples, a total of 96 polymorphic markers and 81 RAPD phenotypes were revealed, showing variation between subspecies, locations and primers. The presence of overlapping RAPD phenotypes was detected between subspecies, locations and samples within each location. The genetic structure was analysed, based on molecular variance (AMOVA), genetic distances (Fst), multidimensional scaling (MDS) and cluster analysis (UPGMA). AMOVA revealed that diversity among locations within each subspecies was the most significant diversification factor (58.68% of total diversity). In addition; Fst, MDS and UPGMA indicated that the distinction between the 6 studied A. fabae populations was related to both subspecies and location. These results strongly suggest that a conjugated effect of subspecies and region governs the genetic differentiation of the A. fabae complex in Tunisia. Both factors should therefore be taken into account for the implementation of a controlling strategy. Key words: Aphis fabae, genetic diversity, subspecies, location, RAPD-PCR. INTRODUCTION phis fabae Scopoli, commonly called black bean aphid, is a major constraint of faba bean (Vicia faba L.) production, causing a destructive damage throughout the world. In addition to direct plant injury, aphid infestation damages faba bean due to honeydew excretion on the leaves, which interferes with physiological processes in the host plants (Hurej and Van Der Werf, 1993). Furthermore, this aphid vectors the bean leaf rolling virus (BLRV) and the faba bean necrotic yellows virus (FBNYV) (Katul et al., 1993; Najar et al., 2000; Blackman and Eastop, 2007). A. fabae is holocylic, reproducing sexually on its primary host, the European spindle-tree Euonymus europaea L., and asexually on the secondary hosts. Nevertheless, in regions with warm climate such as the Mediterranean basin, the Middle East and several warm regions in Africa and America; it keeps reproducing exclusively through parthenogenesis (Blackman and Eastop, 2007). Aphis fabae is represented by a complex of at least five subspecies using the same primary host, but differing by the secondary host plant species -|UJ  ,Q Tunisia, A. fabae species complex causes severe yield losses on faba culture. A