Genetic diversity of an invasive pest (Oryctes agamemnon Burmeister, Coleoptera: Scarabaeidae) of date palm in Tunisia, inferred from random amplified polymorphic DNA (RAPD) markers

Abstract

The root borer (Rhinoceros beetle), Oryctes agamemnon (Burmeister, 1847) is an invasive coleopteran pest of date palm trees in southwestern Tunisia introduced accidentally in “Mrah Lahwar” (Department of Tozeur), spread out into “Rjim Maatoug” (Department of Kebili), then into most oases of Tozeur and Kebili departments, where it is now causing a serious damage. We used 101 samples of O. agamemnon collected from 7 oases and 2 date palm varieties, in order to assess several invasion parameters (e.g. level and distribution of genetic diversity, degree of gene flow between populations and number of introduction events). Analysis of molecular variance (AMOVA) of the random amplified polymorphic DNA (RAPD) markers exhibited no significant genetic differentiation in relation with departments (Tozeur vs. Kebili) or host plant varieties (Deglet Nour vs. Kenta), raising the hypothesis that a limited number of founder genotypes would have been at the origin of invasion. A substantial gene flow was revealed among populations, suggesting that the expansion of O. agamemnon, in Tunisian southwestern oases, has been most likely facilitated by human agency, through the propagation of date palm. These preliminary results would provide a framework for more detailed studies on introduced populations of O. agamemnon, in order to help the development of optimized management methods of this insect. Key words: Insecta, Coleoptera, Oryctes agamemnon, introduced populations, gene flow, molecular markers.