A JFK High School student working on a research project sent me questions about the coconut rhinoceros beetle (CRB) situation on Guam. I am posting my answers here so that they are shared with others who are interested. Click on this link to search this web site for more info on CRB. And please don’t hesitate to contact me (Aubrey) directly if you have more questions.
Q: Can you tell us a little about yourself?
A: Dr. Aubrey Moore, Entomologist, University of Guam (firstname.lastname@example.org; cell 686-5664)
- Damage to and loss of ornamental palms. Impacts tourism, hotel industry and island beauty
- Damage to island ecosystems. On Guam, coconut is the second most abundant tree. Impacts to the ecosystem from rapid mortality of these trees is unknown
- Damage to agriculture. Damage to and loss of palms reduces productivity of coconut and oil palm plantations
- Damage to island communities. On many smaller islands and atolls, the coconut palm is referred to as the tree of life because this plant provides fresh water, food, woven containers, building materials, clothing, income, and fuel. If CRB spreads to these islands, residents may be forced to leave home.
- Adult females lay about 100 eggs during their lifetime. If all of these eggs hatch, go through a complete life cycle and become adults, there will be a population growth rate of 5,000% per generation. Generation time is about 9 months on Guam. CRB population explosions occur when there is an abundance of breeding sites in the form of piles of dead, organic material such as those caused by typhoons or land clearing
- Adults and grubs spend most of their lives in protected habitats: either inside logs or underground.
- CRB has spread to all parts of Guam. Most breeding sites and damaged palms are not easily accessible for control operations because they are in the jungle or on military bases.
- Invasive species often escape natural control when they invade a new island. This means that they don’t have to deal with parasites, predators or diseases which suppress populations within their native ranges. On Guam, predation of CRB is very low because another invasive species, the brown treesnake, has removed many vertebrate predators such as insectivorous birds and mammals.
- A tactic which has been very effective for dealing with many island invaders which have escaped natural control is called biological control or biocontrol for short. Biocontrol is implemented by importing and releasing biocontrol agents, which may be predators, parasites or pathogens, which kill the target pest. Care is taken to select biocontrol agents which will not impact nontarget species. In the case of CRB, there are only two effective biocontrol agents. Both are pathogens, a fungus and a virus, which only attack rhino beetles. Both pathogens have been released on Guam, but only the fungus is killing CRB. The virus, which successfully controlled CRB invasions on Pacific Islands in the past, does not kill CRB on Guam. Turns out that Guam is dealing with a biotype called CRB-G which is apparently resistant to the virus. CRB-G has also recently invaded Hawaii, Papua New Guinea, Soloman Islands, and Palau. Entomologists are currently searching for an isolate of the biocontrol virus which will kill CRB-G.