Genetic Variation and Invasion History of the Invasive Red Palm Weevil (Rhynchophorus ferrugineus (Olivier)) in Terengganu

Abstract

In 2007, the red palm weevil (RPW) Rhynchophorus ferrugineus, was first detected on coconut palms by the Terengganu Department of Agriculture (DOA) in Terengganu districts. As of current time, it has been recorded in other states including Kelantan, and Pahang. As a lethal pest of coconut, sago and oil palm, early symptoms of R. ferrugineus are hard to detect, with detection of its final stages only when the tree is beyond saving. Well- known as an invasive species, knowledge of the genetic make up of R. ferrugineus is important, as it will contribute valuable information to a more detailed program to monitor and control it before it adapts to one of Malaysia’s cash crop, the oil palm. As R. ferrugineus is similar in morphology to another native species R. vulneratus, a molecular marker namely cytochrome c oxidase subunit 1 (CO1) gene was utilised to verify the identity of suspected R. ferrugineus samples and to compare genetic variations within different morphs of R. ferrugineus in Terengganu. For this study, 30 individuals of R. ferrugineus were chosen, with 5 samples each from six Terengganu districts. A 600 bp product was obtained from the Polymerase Chain Reaction (PCR) conducted which was then sequenced. Results revealed that all 30 samples were 100% similar in nucleotide bases and is same with the R. ferrugineus DNA sequence in the National Centre for Biotechnology Information (NCBI) database, which verifies its presence and existence in Malaysia. Additionally, the haplotype obtained in this study was the H8 haplotype, previously recorded from the Mediterranean area. High genetic similarity between samples suggest that the Terengganu populations were from a single founder population, which is common in invasive species. Findings of the haplotype H8 is concurrent with current hypothesis of the R. ferrugineus origins from Middle East. Recent studies that the newly discovered R. ferrugineus at Fujian, China shares the same haplotype with those in Terengganu. More studies are recommended in order to investigate other possible invasive pathways of R. ferrugineus. Keywords: Red palm weevil, Rhynchophorus ferrugineus, genetic variation, mitochondrial cytochrome oxidase 1 (CO1).