Saving coconuts in Southeast Asia and Pacific islands
Biological pest control enlists natural enemy to combat coconut beetle
12 April 2005, Bangkok - A tiny parasitic wasp may help save the coconut industries of a number of countries in the Asia and Pacific region from a destructive pest that feeds on the developing leaves of the coconut palm, the UN Food and Agriculture Organization (FAO) said today.
Severe attacks by the coconut hispine beetle (Brontispa longissima Gestro) can destroy palm leaves and significantly reduce coconut yields. If a palm is young or suffers from poor growing conditions, it may die.
The beetle has invaded coconut plantations in the Maldives, Nauru, Thailand, Viet Nam, the Lao's People's Democratic Republic and China, causing massive losses to local coconut industries. In response, FAO has launched biological control projects in all the affected countries aimed at achieving long-term control of the pest with the help of one of its natural enemies.
"Biological control has proven to be the most effective and we are currently mass-rearing a small wasp parasitoid, Asecodes hispinarum, which attacks the larvae of the beetle, to control the spread of the pest and bring it to non-economically damaging levels," said Wilco Liebregts, an FAO consultant and expert in biological pest control.
Within several months of its release in southern Viet Nam in August 2003, the parasite caused significant reductions in beetle densities and damage to coconut palms, and trees showed clear signs of recovery, returning to pre-infestation production levels.
Spread of the pest
The coconut beetle is widespread in areas of Indonesia, Malaysia, Papua New Guinea and a number of Pacific island countries. However, this invasive pest is new to continental Southeast Asia where, in the absence of natural enemies, it is rapidly spreading and causing massive damage.
The beetle was first detected in Viet Nam, the Maldives and China within the last five years, and is believed to have been imported with ornamental palm trees.
"If left unchecked, the beetle's spread into Bangladesh, India, Myanmar and Sri Lanka will have a similar devastating impact on the smallholder and plantation coconut industry in those countries, putting at risk the livelihoods of a great number of people dependent on this crop," said Keith Chapman, FAO Industrial Crops Officer in Thailand.
Economic loss and threat to livelihood
Coconut palms provide many basic products ranging from fresh drink, food, oil, fiber, oleochemicals and household utensils to timber and building materials. They play an important role in the environment, health, food security and livelihoods of many people in the region.
In the Maldives alone, economic losses caused by the pest are significant. There, coconut is not only an important local food crop, but is perhaps even more important for the tourism industry. Management from one resort island estimated losses between June 2000 and February 2003 at US$ 237 000 already due to a decline in tourism because of unhealthy palm trees and shift in labour from productive activities to insecticide application. Losses in revenue from coconut sales and drinks are estimated at a further US$33 000 for the same period for the holiday islands.
A study commissioned by FAO showed that if left uncontrolled, the beetle infestation would cause in excess of US$1 billion in damage in Viet Nam alone, seriously threatening the survival of the coconut industry there. Assessments of the damage in the other affected countries indicate that the pest would have a similar impact there.
The control of the pest has therefore become of international concern and is of highest priority to the governments of the countries in the region. In China, the pest has been elevated to a status of second most important forestry pest, even though only a few provinces have a sufficiently warm climate to allow the coconut to grow.
Government authorities in the region responded quickly to the incursion and launched control programmes involving the application of insecticides to the crown and stem of infested trees. In the Maldives and China, large numbers of seedlings and even mature trees were also removed and destroyed. However, the pest continued to spread and chemical control proved not only expensive and ineffective but also a serious health risk to farmers, families and consumers - as coconut plantings are often situated near homes.
"The application of insecticides can only serve as a temporary control measure," said Tran Tan Viet, a biocontrol specialist at Nong Lam University in Viet Nam. "Biological control is the most effective method, given the cost and benefit ratio."
Most countries, however, lack expertise in biological control in general and of this pest in particular. To build capacity in these countries in biological control of pests and increase public awareness on non-chemical, environment-friendly control methods, FAO is helping them develop integrated pest management programmes that follow international standards set by FAO. This support has assisted the countries in identifying the coconut hispine beetle to species level, in collecting and importing natural enemies of the beetle from Samoa in the Pacific, in rearing them in captivity for evaluation, and in releasing them into the fields.
FAO is now assessing the effectiveness of these exotic natural enemies in controlling the beetle and in helping to develop integrated pest management strategies that suit each country's unique environment.
"The biological control programmes of the coconut hispine beetle are excellent examples of achieving sustainable, long-term control of a very damaging invasive alien pest that minimizes impacts on the environment and the countries' unique indigenous biodiversity," said Peter Kenmore, an FAO expert in pest management.
Information Officer, FAO
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