Every other day inside a lab on the third floor of the St. John Plant Science Laboratory building on the University of Hawaii at Manoa campus, doctoral student Kristen Gaines opens up a refrigerator full of beetle larvae, hoping to find them dead.
“When I see a dead one, it’s still pretty gratifying,” she said.
Gaines is a research assistant investigating a virus to kill the coconut rhinoceros beetle, also referred to as CRB, which is decimating Oahu’s coconut and palm trees. After years of trying to eradicate the beetle, the problem has grown to a full infestation, with thousands of trees dead because of the pest.
The virus Gaines is testing is a variant of the oryctes rhinoceros nudivirus, referred to as OrNV, which was discovered in the 1960s by German scientist Dr. Alois Huger, according to a 2022 report by researchers from New Zealand and Samoa. The virus, which Huger isolated after he killed healthy beetles by feeding them ones that had died of the virus, was the first time Samoa was able to successfully manage the pest after its introduction in 1910 from a Sri Lanka cargo vessel.
Preliminary results from her testing are promising, Gaines said. She’s observed larvae die after contracting the virus both by injection and naturally from deceased larvae. Most recently, she said, three out of four larvae died after she placed them inside a bin with a dead infected specimen.
Lack of testing facilities
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Several East Asian and Pacific island nations have used the virus or variations of it to manage CRB for decades. While there is plenty of research that confirms the virus’ efficacy against the pest, there has been little research on how the virus may affect native beetles, such as the Kauai stag beetle, according to UH principal researcher Michael Melzer.
Other island chains that used the virus against CRB had economies more dependent on palm oil where the potential benefits of releasing the virus outweigh the risks or did not have native insects to worry about, Melzer said. The virus is host-specific, meaning it doesn’t mutate to infect other types of creatures, so the main concern is its effect on native beetles and similar insects.
Despite the beetle arriving in Hawaii in 2013, the state did not receive a permit to test the virus until April due to the lack of facilities where the tests could be safely administered and contained, said Jonathan Ho, plant quarantine branch manager for the state Department of Agriculture and Biosecurity.
He said the CRB invasion on Oahu reached the point where it was “all over the place,” and it wasn’t feasible to spray or inject every coconut tree on the island and properly dispose of all the green waste.
“At that point, at the landscape level, biocontrol was the only real realistic solution to mitigate the threat of CRB,” Ho said. “We weren’t going to spray or treat our way out of it.”
He added that despite its efficacy elsewhere in the Pacific, adequate testing is crucial to protect Hawaii’s environment and ensure the right virus strain is being utilized.
Melzer said federal funding the state received to respond to the CRB threat changed from an eradication focus to containment around 2020, ultimately leading to the development of the containment lab and procedures in order to score a federal permit to import the virus and begin testing on larvae.
A near ‘eureka’ moment
The entry to the colony lab, where Tomie Vowell, a member of the research support team, rears beetles for experiments on request, is a secure, pitch-black room that serves as a bridge between the lab and the hallway. If a beetle were to escape — one never has, according to Melzer — it would get confused in the darkness. A single light in the corner would be turned on to attract the beetle so it could be recaptured.
“We basically just don’t want that virus leaving the lab, because we don’t know what impact it might have on both native or beneficial insects in Hawaii,” Melzer said.
From the dark room is a door that leads to the lab, where there are four locked refrigerators with beetles at different life stages in various labeled containers.
CRB eggs resemble small white balls. Once hatched, the tiny, pale grubs grow up to 2-1/2-inches long with a strong, black exoskeleton adorned with a rhinoceros-like horn and fuzzy underbelly. Their natural life cycle from grub to adult is typically a year, Vowell said.
Melzer traveled to Palau to get the virus strain the island nation had used successfully to combat the beetle, and brought it back to Hawaii.
In a separate lab, Gaines dresses in full protective gear before injecting the virus into CRB larvae. The infected larvae become lethargic as their gut becomes inflamed.
Gaines said the first time she suspected a larva exhibiting symptoms had died of the virus, it was “not quite a eureka moment, but close to it.”
It can take two to four weeks for larvae to succumb to the virus, Melzer said, while infected adults live longer but ultimately become too lethargic to eat and starve to death.
He said the virus is effective because the beetles live long enough to spread the infection to others but in the end die themselves within weeks.
‘It’s already too late’
If everything goes to plan, Melzer estimates the virus could possibly be released into the wild within two years. Ho said the timeline is dependent on state and federal regulatory processes.
For some landscapers, the window for effective CRB containment has long closed.
“It just sucks because there’s a lot that could be done,” said Brent White, owner of Lush Palm Landscapes. “Maybe you should just let that thing (the virus) go out now and kill the beetles. It’s already too late. The North Shore is already gone. All the trees on the North Shore are going to be cut down pretty soon, they’re all going to be gone. There’s no saving it now — sorry, too late — which is really sad.”
White said he’s turned to treating his palm trees nightly with essential oils, which has helped keep his trees alive, but takes a lot of labor.
“It’s still so hard,” he said. “The minute you stop treating, the beetles come back and attack the tree. It’s just really sad that it’s growing out of control and there wasn’t proper mitigation methods in the beginning to stop it from happening.”
Chance Correa, owner of Malama Aina Landscape and Masonry Design, and Daniel Anthony, founder of nonprofits Hui Aloha ‘Aina Momona and Aloha Organic, agree. The two employ Korean organic farming techniques to combat the beetle.
“In two to four years, we could lose every coconut tree,” Correa said. “There might not be coconuts to farm. It’s that bad.”
Aloha Organic uses a sulfur mixture to deter the beetle, Anthony said, along with nutrients to feed the trees.
“We noticed that the healthier your tree was, the more resilient it was to the beetle,” he said.
Anecdotally, Anthony’s methods have worked. During a visit Thursday, the residential property he’s been treating monthly in Kaaawa had plenty of coconuts in its trees, while a next-door neighbor’s trees showed evidence of beetle damage.
For both Correa and Anthony, coconuts are part of their culture that helped their ancestors survive for centuries.
“It’s life or death for us, for our culture, for our community,” Anthony said.
The two also share concerns about the long-term effects of chemical use on the trees and the fruit they produce.
More testing planned
Existing recommendations from the Department of Agriculture and Biosecurity to combat CRB include chemicals, organic options such as fungi and physical barriers such as netting. Ho said that while he has not heard of sulfur successfully deterring the beetle and it hasn’t been formally studied, any organic option that can be replicated would be welcome.
Basal oil is another organic option to repel beetles, according to the agency’s website.
Ho said the process for a pesticide to get approval for use against CRB does not necessarily require the same type of rigorous testing on its effects on native species that a bio-agent such as the virus does. But, he explained, both the U.S. Environmental Protection Agency and the state have labeling processes for use as a pesticide.
He added that the chemicals listed on the agriculture department’s website are labeled as being usable and then tested by either UH or a survey response to test efficacy.
Other than treating palm trees, Ho said the best way to manage CRB until a successful bio-agent is approved is to manage green waste and prevent breeding.
In the meantime, Melzer and Gaines plan to begin testing the virus against native species and potentially bring in a different strain from another affected area to build a virus “library.”
Melzer said he also hopes to get a permit to test on adult beetles, which so far has not been approved due to the risk of the winged insects escaping by flight.
“We rear CRB for research purposes and we’ve never lost an adult out of there,” he said. “We’re hoping to convince them that we’re never going to lose an adult over here.”
If a permit is not obtained, Melzer said, UH will have to look at better bio-containment facilities so it can finish the testing process.
“Everyone recognizes how important it is that we have these facilities, not even just for CRB, but for other things in the future,” he said. “CRB will not be the last impactful invasive species in Hawaii.”