(2017) found that the Guam population had a distinguishing nucleotide substitution in the mitochondrial COI gene and designated this new haplotype as CRB-G (clade I), to distinguish it from other populations which were designated CRB-S (clades II, III, and IV) 9. Control attempts with commonly released OrNV biocontrol isolates were unsuccessful. However, a CRB population with tolerance to OrNV recently appeared in Guam and spread throughout the island 9, 10. The introduction of OrNV-infected beetles into palm-growing sites in the Pacific beginning in the late 1960s was a successful case of classical biological control and successfully reduced palm damage 2. OrNV then is transmitted among individuals in an infesting population by feeding on food contaminated with OrNV-containing feces of infected beetles, and also during mating with infected insects 8. Control with OrNV involves releasing adult beetles inoculated with OrNV into CRB infested areas 7. Because control with chemical insecticides was ineffective and unsuitable due to labor costs and negative effects on both humans and the environment, control of CRB has relied on natural enemies, particularly Oryctes rhinoceros nudivirus (OrNV) 6. To manage outbreaks of CRB, various control campaigns were conducted 4, 5. Thus, CRB uses the coconut palms as a resource during all of its developmental stages, though they can use alternative food sources as well. Furthermore, adult female beetles lay eggs in dead palms, and the hatched larvae feed on the decomposing palm materials 3. This feeding action leads to reductions in both coconut palm growth and nut production due to a reduction of photosynthesis efficiency, and can cause death if the meristem itself is damaged 2. As the meristem of palm is in the crown, burrowing activity commonly damages developing palm fronds, which then generally display a characteristic “V-shaped” notching pattern once unfurled. Adults of CRB burrow into the crown of a palm to mainly feed on the sap. In the Pacific, the coconut rhinoceros beetle (CRB), Oryctes rhinoceros (Linnaeus, 1758) (Coleoptera: Scarabaeidae: Dynastinae) has caused serious damage to palms, including coconut and oil palms. Altogether these results suggest CRB adults in Palau are infected with a less virulent virus, which may affect the nature and extent of OrNV-induced pathology in Palauan populations of CRB.Ĭoconut palms, often referred to as the “tree of life” 1 in the Pacific, provide numerous benefits to human society.
Asiatic rhinoceros beetle full#
Full genome sequences of the OrNV-Palau1 and -X2B isolates were determined and found to be closely related to each other. However, the OrNV-Palau1 isolate exhibited lower viral production levels and longer larval survival times compared to OrNV-X2B in O. Both OrNV-Palau1 and OrNV-X2B, a CRB biological control isolate released in the Pacific, were propagated using the FRI-AnCu-35 cell line for production of inoculum. OrNV isolated from Palauan-sourced CRB was designated as OrNV-Palau1. Hemocoel injection of CRB larvae with crude virus homogenates from these tissues resulted in viral infection and mortality. In PCR-positive CRB-G tissue specimens from Palau, viral particles were observed by electron microscopy. No significant difference in OrNV prevalence between the haplotypes was detected. In this study, more than 75% of pheromone trap-captured adults of both haplotypes were Oryctes rhinoceros nudivirus (OrNV)-positive by PCR. In the Palau Archipelago, both CRB-G and another haplotype (clade IV) belonging to the CRB-S cluster coexist in the field.
Recently, a remarkable degree of palm damage reported in Guam, Hawaii, Papua New Guinea and Solomon Islands has been associated with a particular haplotype (clade I), known as “CRB-G”.
Coconut rhinoceros beetle (CRB), Oryctes rhinoceros, is a pest of palm trees in the Pacific.
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