AFTER initially being detected in Sept. 11, 2007 in Tumon Bay and Faifai Beach, the coconut rhinoceros beetle continues to spread and has now spread throughout the island, according to University of Guam Entomologist Dr. Aubrey Moore.
In 2007, according to Moore, the beetle population was only localized along the Tumon Bay area. But about three years ago, he said, the population escaped and spread up north and then it covered the middle of Guam.
“Now it is heading down south. We are seeing a bit of defoliation, seeing that V-shaped cut in the leaves. We are not seeing a lot of tree mortality at this point. We have seen younger trees that have been killed,” he said.
Moore emphasized that these trees have been structurally compromised. “I’m really worried when the next typhoon comes because if we have high enough winds, some of those trees will have their tops blown off.”
He stated: “We are seeing little tree mortality. Population level is low but it has spread all over the island.” He said the rhino beetle population was at first contained in a small area. However, now the “wave basically covered the whole island.”
Moore said they had a good chance of eradicating the rhino beetle when it was detected several years ago. However, there was no money readily available and it took six months after detection before the emergency grant money came in.
“We don’t have a war chest for invasive species. It took us about six months after detection to get emergency grant money and hire some people before we actually got boots on the ground. We lost a lot of time. That’s almost one generation. So, if we started a few months earlier, we might have wiped it out years ago. We’ll never know,” he stated.
According to a 2011 Environmental Assessment Report on the CRB Eradication Program on Guam, surveys done after initial detection indicated that the “infestation was limited to the Tumon Bay and Faifai Beach.” At first, an area of 900 acres was quarantined by the Guam Department of Agriculture. The quarantine zone was later expanded around 5,830 acres.
The beetle is native to southeast Asia and now thrives throughout much of Asia and the Western Pacific, the report noted. Aside from Guam, this invasive species “was accidentally introduced and is now established on the Pacific islands of Palau, Fiji and Samoa.”
Moore said the rhino beetle invasion in Palau started in the 1940s and caused the eradication of 50 percent of the coconut tree population on the island.
“Some of the smaller islands – there were no more coconut trees; [they were] totally wiped out. We are very similar to Palau and we don’t want that to happen here. That’s why we are trying to put a lot of work here to prevent that from happening,” he explained.
Roland Quitugua, operations chief of the Guam Rhino Beetle Eradication Program and another rhino beetle expert, said the introduction of a virus in Palau curtailed the beetle population there.
Moore, however, said the same virus introduced in Palau, which has been a major control tactic throughout the Pacific, did not work on Guam.
“We actually introduced the same virus, not just one strain but eight different strains and nothing killed our beetles. The virus didn’t work on our beetles at all. This was a real shock.”
He explained: “There’s two possibilities and we are going to test [them] in the next few months. One possibility is that the beetles have become resistant to the virus and another possibility is that the virus stocks in the laboratory have gone bad. So we have to find an answer to that. We were counting on the virus working. This is called biological control. That’s when you use an organism to control another organism. It totally failed for us when we used the virus but we switched gears and used a fungus that they are using in the Philippines and we brought some over here and it really works on our beetles.
“We have been contacted by officials in Palau and they are very much interested in getting some of the fungus that we have been using on Guam and seeing if they could procure some in the Philippines to help in their eradication or management program."
The Guam Rhino Beetle Eradication Program employed several methods of eliminating the rhino beetle population. Since the program started in 2007, they have employed quarantine, pheromone traps, sanitation, detector dogs, chemical control, and bio control.
Quitugua said: “We are still in eradication mode. Actually, since we have been using metarhizium, the population of the CRBs has gone down in seven consecutive months. Only in the last months did we see a rise again.”
Metarhizium is a type of fungus currently used as a bio-control method for rhino beetles. According to the CRB assessment report, metarhizium has the ability to penetrate the insect’s hard exoskeleton.
Quitugua said the program also tried using detector dogs to identify breeding sites but had to discontinue the program because it was economically unfeasible.
Sanitation, he said, is another method of eradicating the rhino beetle population.
He explained: “What we’ve also noticed is that there is a difference in incidence of CRBs in managed trees versus unmanaged trees. In areas where trees are kept clean, we see a lower incidence of CRB damage. So they seem to like these trees with a lot of organic matter in the crowns of the trees and that is where we find breeding sites.”
Quitugua also noted that in the northern areas, near Ritidian Point, they have found out that another “invasive species” on the island has been helping deplete the population of the rhino beetles. He said feral ungulates or wild pigs are using the grubs as a food source.
“In these areas, breeding sites are few, and we are attributing that to the feral pig population. Rhino beetle breeding sites are at ground levels. It looks like the wild pigs are going after the grubs. The reason why we are attributing that is because in areas where we see a lot of feral pig activity, there are very few evidence of CRBs on the ground. But we are finding them anywhere from 2 to 3 feet above the ground because the pigs cannot reach them,” he explained.
According to Moore, they are also working on several possible methods for their eradication program, including a hormone growth regulator that prevents the rhino pupa from reaching maturity.
Quitugua said new funding support is now allowing them to do research and improve their methodologies.
“When the rhino beetle eradication first started, the funding sources prohibited research and that was a big problem because this is new. And when something new comes into an area, you just can’t take everything from other places and just implement and think that it’s going to work in the exact same way,” he explained
Moore also mentioned they are trying to develop control methods that will work just in case current eradication methods fail.
Moore said the best thing to do is to have an effective quarantine system in place. He explained: “If something does come in, if this is detected early enough, and if it is in a really small area, you’ll have a greater chance of eradicating it. “
“With the crew that I have now and the current funding levels, we are able to make some progress but I can tell you that with more funding we would be able to make greater progress,” Quitugua stated.
He added: “I only have a 12-man crew to cover the entire island. These guys have to go into areas, go into deep jungle. Some of the areas these guys go, it takes them an hour to get there. We are making do with what we can, but the one thing for sure is we cannot stop. We are making progress.”
So far, according to Moore, the program has been spending around $600,000 a year to run the eradication program. Their funding comes from federal sources such as USDA-APHIS and the local government.
An area that needed to be addressed, according to Quitugua, is policy and enforcement with regard to invasive species.
“As a result, with the rhino beetles, we found some gaps in laws and so the GIC is going to address that.” He added, “The Guam Invasive Council is working towards reviewing enforcement and policies, including quarantine regulations.”