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Coconut beetle management in Cambodia

Hean Vanhan*

Abstract

In Cambodia, there is no large-scale commercial cultivation of coconut palms or coconut industry and no data on coconut production. Coconut palms are the main feature of family gardens and green or mature coconuts provide regular income. During the last five years, coconut palm plantations have been developing in some provinces. A preliminary survey conducted in 2004 showed that there were at least 12 million coconut palms in Cambodia.

Among the coconut pests in Cambodia, rhinoceros beetle (Oryctes rhinoceros L.) is well known among Cambodian farmers and was believed to be the only insect t    hat could attack coconut palms.

In late 2001, coconut beetle (B. longissima) was recorded as a new pest in Cambodia. The first infestations were recorded in an area near the Vietnamese border, especially young coconut plantations, which had introduced seedlings from Viet Nam. Owing to the lack of expertise and experience on this new invasive alien species, within two years it had spread over the whole country. This new threat caused significant damage to coconut trees (on average 74 percent of coconut palms were attacked, resulting in mortality of 21 percent).

To combat this problem, the Department of Agronomy and Agricultural Land Improvement (DAALI) of the Ministry of Agriculture Forestry and Fisheries took appropriate action (phytosanitary measures, pest outbreak intervention via insecticide and extension on control measures) to control and reduce the pest’s spread. Unfortunately, the beetle is still established and inflicting significant damage in Cambodia.

The losses induced by this invasion have affected Cambodian farmers. Assistance from other countries in the region with experience in B. longissima attack and FAO support were needed for successful control of the pest.

Introduction

Cambodia is located in Southern Asia, bordering the Gulf of Thailand, between Thailand, Viet Nam and Lao PDR (Figure 1).

The estimated GDP rate in 2003 was 5.5 percent. Agriculture accounted for 30 percent and employed 75 percent of the workforce. Rice production (GDP 13 percent) occupies 91 percent of the cropped area. Industry and services constitute 40 and 30 percent of the GDP respectively.

Rice is the main crop in Cambodia and is grown in all provinces. In 2003/2004, the total rice-cultivated areas were 2 315 853 hectares but because of drought only 4 710 957 tonnes were harvested.

DEVELOPING AN ASIA-PACIFIC STRATEGY
FOR FOREST INVASIVE SPECIES:
THE COCONUT BEETLE PROBLEM 
BRIDGING AGRICULTURE AND FORESTRY

Figure 1. Map of the Kingdom of Cambodia

In Cambodia, there has been no large-scale commercial cultivation of coconut palms or coconut industry and there are no data on coconut production. Coconut palms are the main feature of family gardens and green or mature coconuts provide regular income. Coconuts are used for their juice when green and when they have matured their milk is used for flavouring food. Coconut palm plantations are developing in some provinces of the northeast, such are Rattanac Kiri and Mundul Kiri and in the southwest (Kampong Speu, Kampot, Sihanoukville and Koh Kong). There are no clear data on coconut production and it is difficult to calculate the production area, but according to the results of a primary survey conducted in 2004 by the Plant Protection and Phytosanitary Inspection Office (PPPIO) there are at least 12 million coconut palms in Cambodia. The biggest production areas are Kampot Province (2 699 000 palms), Kampong Speu (2536 000 palms), Sihanoukville (2 404 000 palms) and Rattanac Kiri (1 864 000 palms) (Table 1).

Table 1. Distribution of coconut palms in Cambodia

Provinces/cities

No. of palms

Provinces/cities

No. of palms

Banteay Mean Chey

43 000 Preah Vihear 39 000
Battambang 101 000 Prey Veng 39 000
Kampong Cham 148 000 Pursat 215 000

Kampong Chhnang

563 000 Rotanakiri 1 864 000
Kampong Speu 2 536 000 Siem Reap 101 000
Kampong Thom 93 000

Preah Sihanouk Town

2 404 000
Kampot 2 699 000 Stueng Treng 103 000
Kandal 212 000 Svay Rieng 33 000
Koh Kong 688 000 Takeo 290 000
Kratie 101 000

Otdar Mean Chey

24 000
Mondulkiri 41 000

Kep Town

n.a.

Phnom Penh City

n.a.

Pailin Town

n.a.

Total: 12 337 000

Source: Department of Agronomy and Agricultural Land Improvement (DAALI), 2004/ MAFF (n.a. = not available)

Brief overview of coconut pests in Cambodia

Rhinoceros beetle (Oryctes rhinoceros L.)

Coconut pests in Cambodia have yet to be studied scientifically, but farmers are well acquainted with the rhinoceros beetle as a pest that attacks their coconut palms.

Coconut beetle (Brontispa longissima)

The coconut beetle is one of the most damaging pests of coconut and a range of ornamental palm species. Both larvae and adults feed on the tissues of developing, unopened leaves. The beetle can cause significant production losses, and high infestation levels may result in palm death.

Coconut beetle is most likely indigenous to Indonesia, Malaysia and Papua New Guinea. There is no record of its existence in Southeast Asia before the latter half of the twentieth century, when it was probably introduced into southern Viet Nam through the importation of ornamental palms. Currently Brontispa has established and is inflicting significant damage in numerous Southeast Asian countries, most notably in Viet Nam, Southern China and Thailand, which have significant coconut industries. The pest has also been confirmed in Singapore, Lao PDR and in late 2001 was recorded as a new pest of coconut palm in Cambodia.

In December 2001, the PPIO received a report on strangled coconut disease from Mundul Kiri Province, on the border of Viet Nam, where coconut plantations were expanding. Inspection revealed the spread of coconut beetle on coconut palms throughout the province. Farmers did not initiate control measures, because they believed the damage was caused by drought and climatic conditions. The pest was probably introduced into this province through the import of infested coconut seedlings and ornamental palms and could also have arrived via natural transboundary movement from Viet Nam.

Consequently, DAALI conducted a survey on the distribution of coconut beetle in the whole country. However, owing to lack of expertise and financial constraints, this primary survey took more than two years. On an average 74 percent of coconut palms had been attacked nationwide resulting in death of 21 percent of palms.

Coconut beetle management in Cambodia

At the beginning of 2002, the Ministry of Agriculture, Forestry and Fisheries (MAFF) advised the Provincial/Municipal Department of Agriculture, Forestry and Fisheries (PDAFF and MDAFF) and Provincial/Municipal Department of Agricultural Extension (PDAE and MDAE) to take the following measures to combat the spread of coconut beetle outbreaks with technical guidance from DAALI.

Phytosanitary measures

Reduce spread potential from one region to another by controlling the movement of coconut seedlings, coconut leaves (and items made from them), ornamental and other palms from infested areas. Raise national awareness on the pest and the danger of facilitating the beetle’s arrival in new areas (Figure 1).

Coconut beetle outbreak intervention

Owing to inexperience, the DAALI intervention team decided to use chemicals to disinfect heavily infected areas and to control the beetle’s spread.

A soluble powder of Cartap or Nerestoxin packed in tissue bags of 30 g were placed on the top of the young palms (shorter than 2.5 m) (Figure 2). One bag was put into the leaf base around the first unopened leaves, and applied again within 20 to 30 days. For young palms, 30 - 40 g of granulated carbofuran 3G or diazinon 10G, was placed on the top of each tree either directly or packed inside tissue bags.

DEVELOPING AN ASIA-PACIFIC STRATEGY
FOR FOREST INVASIVE SPECIES:
THE COCONUT BEETLE PROBLEM 
BRIDGING AGRICULTURE AND FORESTRY

Figure 1. Raising national awareness on the coconut beetle

DEVELOPING AN ASIA-PACIFIC STRATEGY
FOR FOREST INVASIVE SPECIES:
THE COCONUT BEETLE PROBLEM 
BRIDGING AGRICULTURE AND FORESTRY

Figure 2. Placing bags of insecticide on top of the coconut palms

For mature coconut palms, Actara 25WG (thiamethoxam) was injected into the trunk at 1 g/palm; this afforded 100 percent control for up to 120 days and no residue was found in coconut milk at seven days after treatment (detection limit 0.01ug/ml) (Figure 3). This treatment is more popular with Cambodian farmers, because the danger of climbing the palms and pollution of the environment are avoided.

Extension on coconut beetle control

Extension activities on coconut beetle control were conducted by the DAALI intervention team in collaboration with the PDAFF or MDAFF (Figure 4 & 5). Field-level training was conducted at the same time as demonstration. Twenty to 30 farmers in infested areas were invited to the training to discuss the pest’s spread, study the beetle’s morphology and biology, raise awareness on control methods, analyse the efficacy of botanical insecticide available in the area and learn safe and responsible measures for pesticide use.

DEVELOPING AN ASIA-PACIFIC STRATEGY
FOR FOREST INVASIVE SPECIES:
THE COCONUT BEETLE PROBLEM 
BRIDGING AGRICULTURE AND FORESTRY

Figure 3. Injecting Actara into a trunk

DEVELOPING AN ASIA-PACIFIC STRATEGY
FOR FOREST INVASIVE SPECIES:
THE COCONUT BEETLE PROBLEM 
BRIDGING AGRICULTURE AND FORESTRY

Figures 4 & 5. Extract of Neem leaves and extension activities for coconut beetle control

DAALI pamphlets on the coconut beetle and control measures were distributed to the Farmer Field School and DAALI intervention activities were subsequently monitored by associated staff.

Conclusions

Currently B. longissima is established and inflicting significant damage in Cambodia. The losses caused by this invasion are affecting Cambodian farmers. Chemical control measures have proven inadequate to control the beetle’s spread. In addition to the high and often prohibitive economic costs, the method is often cumbersome since the insecticide is to be introduced into all the palm crowns.

Owing to internal inexperience on coconut beetle control, efforts were unsuccessful. Assistance from other countries in the region with experience in B. longissima attack and FAO support were needed for successful control of the pest.


* Deputy Director, Department of Agronomy and Agricultural Land Improvement, Ministry of Agriculture Forestry and Fisheries; e-mail: vanhan@mobitel.com.kh; tel: (855) 12818216; fax: (855)23 216655

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