UOG Explores Possible “Bio-Control” for Guam’s Rhino Beetles


Guam – The University of Guam Cooperative Extension Service Agriculture and Natural Resources unit has been working with visiting insect pathologist from New Zealand, Dr. Sean Marshall to test bio-control measures for the coconut rhinoceros beetles (CRB) that have been plaguing Guam for over six years.  

Marshall brought with him several strains of the highly specific Orcytes virus that have been successfully used in Samoa, Fiji, Tonga, Palau and other Pacific islands for CRB control.

“A strain of this virus was previously disseminated to Guam’s rhino beetle populations in 2010, but results were surprisingly disappointing,” said University of Guam entomologist Dr. Aubrey Moore. “We are working to find out what went wrong with our first attempt and find a strain of the virus that will work here.”

Marshall was on Guam in January and is still analyzing data from these experiments as well as conducting on-going bioassays to match the most effective virus strain to Guam’s rhino beetles. He is feeling more optimistic on this visit. He has been dissecting dead beetles that were exposed to the virus and the post mortem indicates the virus killed them. 

As a scientist with AgResearch Limited in New Zealand, Marshall cultivates the Orcytes virus in his laboratory. “While trying to understand why the first attempts to use this virus did not go well on Guam (but have worked on other island CRB populations), I decided to do a comparative DNA analysis of CRB and discovered the Guam population was different from beetles found in Samoa, Fiji, Papau New Guinea, Diego Garcia, and Malaysia,” said Marshall.

He is continuing to collect and analyze DNA samples of beetles from Philippines and Palau hoping to understand where the rhino beetles on Guam originated. “It is very interesting to note that Marshall’s DNA studies have also shown that the CRB recently found in Hawaii appear to be genetically identical to Guam’s beetles,” said Moore.

Marshall has recently had his applications approved by the New Zealand government to bring live CRB into his lab in order to continue his experiments to test bio-control isolates with pest genotypes and assist University of Guam scientists in their efforts to save Guam’s palm trees.

“We hope to secure funding to keep this important work ongoing and contain the rhino beetle populations on Guam and keep them from spreading any further into the region,” says Moore.