Undescribed Color Polymorphism of the Asiatic Palm Weevil, Rhynchophorus vulneratus Panzer (Coleoptera: Curculionidae) in Indonesia: Biodiversity Study Based on COI Gene

Abstract

Palm weevils are notorious insect pests of coconut palms in Indonesia and other palm species worldwide. Indonesian palm weevils exhibiting a rusty red marking on the pronotum are classified as the red palm weevil (Rhynchophorus ferrugineus Olivier; Coleoptera: Dryophthoridae). However, morphology-based identification and crossbreeding studies suggested that these insects are color morphs of the Asiatic palm weevil (Rhynchophorus vulneratus Panzer; Coleoptera: Dryophthoridae). The purpose of this study was to clarify the presence of undescribed color polymorphisms of the Asiatic palm weevil from Indonesia using a partial sequence of the cytochrome oxidase subunit I (COI) gene. The COIs of 107 specimens of palm weevils collected from Indonesia, Saudi Arabia, and Pakistan were amplified using Folmer primers. COI analysis revealed high intraspecific variability in palm weevils from Indonesia and Saudi Arabia. Although Folmer primers of COI are powerful species identification tools in many taxa, they were unsuitable in this research for Indonesian palm weevils because interspecific variation was lower than intraspecific variation. This study concluded that undescribed color polymorphisms exist in the Asiatic palm weevil. The rusty red polymorphisms of the Asian palm weevil might be erroneously identified as R. ferrugineus.