CRB captures hit record low in 2026 as Rota containment holds line

The number of coconut rhinoceros beetles captured on Rota has been trending to an all-time low in 2026, underscoring what officials describe as years of sustained containment efforts against one of the Pacific’s most destructive invasive pests.

Data presented during the third day of the CNMI Biosecurity and National Security Forum last April 8 at the Crowne Plaza Resort Saipan showed just 45 beetles collected so far this year, a sharp decline from peaks of 2,676 in 2020 and 2,274 in 2021, when newly discovered infestation sites drove numbers up.

Rota CRB field supervisor Mark C. Manglona said the drop reflects both aggressive mitigation and a shift in how beetles are being detected.

“The population right now, the CRB dropped,” Manglona said. “It’s been three years that the CRB is contained on Rota right now.”

The coconut rhinoceros beetle (Oryctes rhinoceros)—first recorded in Samoa in 1909—has spread across the Pacific over the past century, reaching Guam in 2007 and later Rota in October 2017. The initial discovery on Rota was traced to Tweksberry Park and the former PauPau Hotel, where the pest was found in a fallen log during routine maintenance.

Officials believe the pest likely arrived via cargo, with Manglona noting that the Rota strain differs genetically from Guam’s population, adding that the beetles may have originated from elsewhere in the region before reaching the CNMI.

Despite early fears, no CRB has been detected on Tinian or Saipan.

Manglona credited early detection and aggressive response for keeping the infestation contained to Rota.

“We discovered them pretty early,” he said. “Once we discover it, everybody’s into it. We make sure everybody gets involved for this one.”

Containment efforts have centered on removing “dead snags”—fallen or decaying coconut trees that serve as breeding grounds—alongside pesticide application, pheromone traps, and night monitoring. Rota currently maintains nearly 500 traps across the island.

“I’m a bat,” Manglona said of his nightly inspections. “I go out and check all the CRB traps… sometimes six hours, seven hours.”

The sharp spike in 2020 and 2021, he explained, came from intensive clearing of newly identified infestation sites. “Those are the new sites that we found and we collected all of them,” he said.

Today, most captures come from traps rather than active infestations, suggesting a shrinking population.

Still, about 100 to 150 coconut trees remain affected, down from as many as 300 at the height of the outbreak. Roughly 60% of the island has seen some level of infestation, though impacts remain limited compared to Guam.

The contrast with Guam—where CRB has devastated coconut populations—was underscored by University of Guam’s Roland Quitugua, who highlighted the cultural toll.

“They used to be able to go out and collect leaves for weaving in one day,” Quitugua said. “Now, it might take them a week to find good, undamaged leaves.”

The destruction of coconut trees has forced some on Guam to rely on store-bought coconut products like coconut milk, a stark shift in a region where the tree is central to food, medicine, and tradition.

That reality helped motivate Manglona to join the fight.

“When I arrived. I asked my cousin in Guam, what is wrong with the coconut tree?” he said. “That’s the reason why I stepped in. Just to keep them out of Rota.”

Beyond chemicals and traps, Rota’s program has also benefited from natural predators such as kingfishers, Mariana starlings, coconut crabs, ants, and monitor lizards, which help suppress beetle populations.

Officials also shared practical tips for the public on how to identify possible CRB infestation, stressing that early reporting remains critical to containment.

Manglona said one of the most visible warning signs is damage to coconut fronds.

“The telltale sign is you see V-shapes,” he said. “It’s like getting a scissor and cutting them into V-shapes.”

He added that internal damage may not always be immediately visible but can eventually lead to the tree’s decline.

“If the tree is dying from the inside,” he said, it may already be infested.

Residents are encouraged to report any suspicious damage—even if they are unsure.

“It’s fine to call in,” Manglona said. “Just to make sure that it’s not a CRB.”

He noted that increased activity is often observed after major events like Palm Sunday, when trimmed coconut leaves can make detection more difficult and lead to more reports.

Beyond visual signs, officials emphasized vigilance in monitoring larvae or unusual beetle activity in yards, farms, or construction areas, especially near decaying wood where CRB typically breeds.

“We need to identify it [and] collect the specimen and always get the GPS and the location,” Manglona said.

But officials warned that the threat remains, particularly from inter-island transport.

“Prevention—that’s the frontliners,” Manglona said, emphasizing the need for strict cargo inspection. While protocols require coconuts shipped from Rota to be husked and cleaned, gaps remain—especially in commercial transport systems where cargo is not always thoroughly checked.

The risk of spread to Tinian and Saipan continues to weigh heavily on biosecurity officials, given the cultural and economic importance of coconut trees.

For now, Rota’s containment is holding, with no new infestation sites detected on the island’s northern side since 2022.

But Manglona caution that vigilance—and funding—remain critical.

“The problem right now we’re having is just the fundings,” he said, pointing to the need for supplies, equipment, and staffing to sustain the gains.