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The expertise of AgResearch scientists in utilising biocontrol agents to fight invasive agricultural pests is being sought by United States officials battling a destructive beetle that threatens the livelihoods of many Pacific Island nations.
The coconut rhinoceros beetle (CRB) has been present for a long time in many parts of the Pacific and has been kept largely under control through the use of a biocontrol virus. However, in 2007 AgResearch scientists identified a new biotype (genetically different) of the beetle in Guam that was found to be resistant to all commonly used strains of the virus.
During the 25th International Congress of Entomology in Orlando, Florida officials from the United States Department of Agriculture met scientists from AgResearch - as well as from other science organisations around the Pacific - to investigate potential management options for the beetle which has a profound impact on the economies of many Pacific nations.
Scientist Sean Marshall, an insect pathologist and molecular biologist at AgResearch says the coconut rhinoceros beetle attacks the developing fronds of coconut trees and kills them when the growing point is destroyed during feeding. For Pacific islands reliant on palms for economic growth, trade and social development the beetle is a very serious issue, he adds. It is even more serious for smaller islands and atolls where the palm is still very much the ‘tree of life’ that people depend on for everything from building materials to food and cultural practices.
“The US officials wanted to hear from us about future strategies to help manage the beetle,” Dr Marshall says.
“This beetle is a significant threat to many US territories in the Pacific including Guam and Hawaii as well as the much wider Pacific basin. This meeting was partly in recognition of the 20 years we’ve been working on this problem, initially dealing with the ongoing management of the beetle but more recently, identification of the new biotype (known as the CRB-G) in Guam, and its spread further afield.
“We have been working on a proposal with the Pacific Community (SPC) and University of Guam to investigate potential new biocontrol options for the new biotype.”
The Pacific Community (SPC) is the principal scientific and technical organisation in the Pacific region and which is owned and governed by 26 country and territory members.
Dr Marshall recently helped identify the CRB-G in Solomon Islands and travelled there at the request of the FAO (Food and Agriculture Organisation of the United Nations) to train local biosecurity staff on management options.
“The damage in Solomon Islands is really quite bad,” he says.
“It started near the capital Honiara and has spread quite a distance since its discovery. The beetle is killing palms, the damage is clearly visible and the coconut and palm oil industries there are very concerned.”
Dr Marshall says release of the original biocontrol virus weakened the pest and provided over 30 years of control and stopped further expansion of the beetle within the Pacific region.
“But, as the new beetle variant has not responded to the original biocontrol virus strains, this has limited the management options currently available. Now we implement robust sanitation plans to eliminate known and potential breeding sites, apply a biocontrol fungus to target breeding sites where removal is either difficult or not feasible, and actively monitor to the detect spread of the beetle into new areas.”
The visit also provided an opportunity for Dr Marshall to test some new strain variants of the CRB biocontrol virus that could one day prove effective against the new beetle biotype. Results from the testing should be known in the next few months.
“Although the new beetle variant has not been susceptible to the virus, training in the use of the biocontrol virus was incorporated to allow further testing, but also because the virus is still an effective control agent against the common variant of the beetle. So if the common variant of the coconut rhinoceros beetle invades one of the other provinces, they will be ready.”
“We hope to find a solution quickly for the benefit of the entire Pacific region,” Dr Marshall says.