Coconut Rhinoceros Beetle (CRB) control and management on oil palm in the Solomon Islands

Oryctes rhinoceros L. is an invasive and destructive pest of palm trees in Southeast Asia and the Pacific including Papua New Guinea and the Solomon Islands. The earlier beetle populations on the Solomon Islands known as the coconut rhinoceros beetle Pacific haplotype (CRBP) are controlled effectively by the biological control agent Oryctes rhinoceros nudivirus (OrNV). Another population of CRB was reported in 2015 on Solomon Island and it was associated with aggressive feeding behavior and huge yield damage to coconut and oil palms. The new CRB population is a novel haplotype (clade I) known as CRB-G and is not affected by the nudivirus. CRB-G progressively invaded Guadalcanal Oil Palm (GPPOL) plantation areas and the surrounding smallholder’s oil palm blocks on Solomon Island, causing remarkable damage to all palms. With the incursion of CRB-G to Oil Palm fields on Solomon Island, a strategic IPM approach was implemented by GPPOL management team. The approach included cultural control by destroying all valuable breeding sites including old palm trunks and EFB decomposition sites. In addition to that, mechanical chipping of fresh palm trunks was implemented to help reduce palm trunk mass as well as increase the chipped matter decomposition rate within a short period. Disc harrow of chipped palm trunks and use of cover crop were also implemented. Moreover, mass trapping with pheromone lure baiting was carried out on a weekly basis. Chemical control was applied selectively, based on beetle population monitoring surveillance and palm damage surveys and assessment reports conducted weekly. Control efforts using this strategy have played an important role in controlling the beetle population and maintaining damage levels on all estates below 5% since early 2020. Ongoing research in collaboration with AgResearch NZ to develop long-term IPM strategies includes evaluating the efficacy of viral biocontrol through field transmission trials. Moreover, one fungus, Metarhizium majus strain, is being evaluated to determine its effectiveness in the field.