Morphological characters of Rhynchophorus spp. (Coleoptera:Curculionidae) associated with sago, coconut, and oil palm in Indonesia

Abstract

Rhynchophorus weevil is known as the most damaging insect pest of palms worldwide and the major pest in sago (Metroxylon Sagu) and coconut (Cocos nucifera) in Indonesia. Nowadays, Rhynchophorus weevil has become a threat to oil palm (Elaeis guineensis) since 2018. This study aims to identify Rhynchophorus spp. morphological characteristics and pronotal color pattern polymorphism in sago, coconut, and oil palm using 16 morphological characters, i.e., length and width of pronotum, elytra, and rostrum. The variations between samples were assessed by one-way ANOVA and principal component analysis (PCA). The results showed three types of pronotal patterns, specifically to the weevil species. They were red stripe, red stripe-spot marking, and black for oil palm, coconut, and sago, respectively. There were no significant differences in all morphological characters of Rhynchophorus spp. in coconut and oil palm. In contrast, 12 morphological characters of Rhynchophorus spp. in sago were different from oil palm and coconut. The Rhynchophorus associated with oil palm and coconut has differences in the pronotal color pattern but has similarities in all morphological characters, identified as R. vulneratus. The Rhynchophorus associated with sago has black pronotal color, and the smaller size is alleged to be R. bilineatus.