Plant Quarantine in Pacific Island Nations
All countries are involved in the export and import of agricultural products, and many depend heavily on agriculture for their export earnings. Reviewing quarantine procedures, and upgrading technology and equipment where necessary, has become an urgent concern for both exporting and importing countries. A key concept in the new free trade situation is Pest Risk Analysis, an objective assessment of the dangers of invasion by a particular pest, and the damage such a pest might do if it were accidentally introduced.
The economies of South Pacific countries are heavily dependent on both tourism and agricultural exports. In addition, the island status of these countries has protected them from many serious pests endemic in Asia and Australia. Not only does this save them the cost of pest control, but their pest-free status is a decided advantage when they are seeking export markets. Quarantine is therefore of major importance to these nations.
In 1996, FFTC began a Five-Year Project on "Plant protection constraints to the production of tropical fruits/root crops in the Pacific", funded by a special grant from the Japanese Government. As part of the project, the Center held a Workshop on Plant Quarantine in Fiji, focusing on Pest Risk Analysis. It was attended by senior quarantine and plant protection officers from South Pacific nations. The training course was then also held in Guam, to allow another group of quarantine officers to attend.
The workshops also gave quarantine officers in Pacific Island countries the opportunity to discuss, and receive extra training in, a computerized information service for plant protection recently developed by the Plant Protection Service of the South Pacific Commission. The commission has also supplied desktop computers and software to quarantine and plant protection officers in FAO member countries in the Pacific.
Pest Risk Analysis (Pra)
Pest categorization is the key component of pest risk assessment. This is not just an identification of the pest species, but an analysis of its potential danger as a pest. A pest of quarantine significance refers to a pest of potential economical importance to the area endangered, but not yet present there, or present but not yet widely distributed and being officially controlled. Pest categorization includes the following major elements.
- Identification of the pest
- Definition of the PRA area
- Distribution and official control programs within the PRA area
- Potential of the pest for establishment and spread in the PRA area
- Potential economic impact potential in the PRA area
- Endangered areas
The other major components of PRA include Economical Impact Assessment (basically a thorough examination of the economic risk associated with the process) and the Probability of Introduction, which looks at the prospects of both entry and establishment of the pest.
Essentially, Pest Risk Management is the process of deciding how to react to a perceived risk, deciding whether action should be taken to minimize the risk, and, if so, what action should be chosen. These steps should provide a clear scientific basis for pest risk assessment, risk management and quarantine decisions, and prevent these from being used in an inconsistent manner and as barriers to international trade.
The Sanitary and Phytosanitary Agreement
This agreement was part of the World Trade Agreement (WTO) and provides a series of rules for WTO members, to ensure that their sovereign rights are not misused for trade protection purposes and do not result in unnecessary barriers to trade.
The major elements of the agreement constitute transparency, reduction of arbitrariness, and implementation of measures to provide the appropriate level of protection. These major elements intend to make the contracting parties to the SPA adopt open and fair trading practices with respect to health protection procedures. The agreement also set up a Committee for Sanitary and Phytosanitary Measures, to discuss issues of concern to both international and national Organizations for Standards. These Organizations are responsible for the formulation of standards, the justification of standards, notification, information dissemination and settlement of any disputes.
Pest Risk Analysis for Viral Diseases of Tropical Fruits
Virus and virus-like diseases have been causing serious damage to fruit production in tropical areas. They are not usually transmitted through seeds, but are often carried across national boundaries by infected bud-wood, vegetatively propagated seedlings and transmission by insect vectors.
With regard to disease risk analysis, the workshop discussed the major virus diseases of banana, citrus, papaya and passionfruit, in terms of the etiology and epidemiology of the diseases, current diagnosis methods, their geographical distribution and their economic impact. The various strains of important diseases such as banana bunchy-top and banana mosaic were described. Plantlets propagated by tissue culture have been found to be more susceptible to banana mosaic than seedlings of sucker origin. Since tissue culture is widely used to produce disease-free banana seedlings, this suggests that intensive vector control is essential in banana plantations where plantlets raised by tissue culture are being grown.
Greening is one of the most serious citrus diseases. It affects most citrus species, and is vectored by psyllids in a persistent matter. Most natural spread probably occurs when young shoots are sprouting, at a time when succulent growth is present on donor and receptor plants, and psyllid populations are high. Recent work by an FFTC survey team, using new methods of diagnosis and indexing, had found greening to have a much wider distribution in the Pacific than previously recognized. Some strains are virulent to pommelo, which had been thought resistant to the disease. This illustrates the importance of using advanced scientific procedures when certifying planting materials, particularly imported ones, as virus-free.
Disease risk analysis has to be followed by control of the diseases. In general, these vector-borne systemic diseases can be effectively controlled by integrated control measures, including production and cultivation of virus-free seedlings, elimination of inoculum sources and prevention of reinfection through IPM of vector insects and cross protection with mild strains. The establishment of pathogen-free nursery systems is the most important way of preventing these diseases from spreading.
Long-Distance Migration of Insect Pests in Relation to Pest Risk Analysis
The Present Situation of Exotic Insect Pests in Japan
The invasion of exotic insect pests into Japan is increasing year by year. The current invasion rate is 1.71 species per year, which is much higher than the rate of 0.61 species per year found in the 1950s. A total of 239 exotic and 85 possibly exotic insect species are recorded in Japan, 75% of which are pests.
The most important exotic pests are greenhouse whitefly, rice water weevil, thrips, alfalfa weevil, silverleaf whitefly, Western flower thrips, and legume leafminer. The last three species have arrived over the past six years, while the others arrived between 1974 and 1982. Characteristics common to all these pests are their wide host range and tolerance to pesticides. Strategies to manage these exotic pest insects differ according to the type of invasion process, the ecological traits of the pest, and its local abundance and/or host range.
Eradication of Fruit FLY and Melon FLY in the Okinawa and Amami Islands
This is an interesting and rare example of the complete eradication of an insect pest. Oriental fruitfly and melon fly were first identified early this century in Okinawa prefecture, the southernmost part of Japan. Because of the wide host range of these pests, strict domestic quarantine rules were put into force immediately. Any plant materials suspected of harboring these insects were prohibited from leaving the infested area. This was a great disadvantage to the export of tropical fruit from Okinawa to the rest of Japan, a major source of income. An eradication program was begun in the late 1960s, applying the male annihilation method against Oriental fruitfly and the sterile male technique against melon fly. Eradication of the two pests was completed in 1993. Monitoring and the mass production of sterile males are still being continued, to protect against reinvasion.
Long-Distance Migratory Insects: The Invasion Process and Forecasting
Brown planthoppers, white-backed planthoppers and rice leaffolders are major exotic pests of rice. Each year, they fly to Japan in June and July, causing serious damage to rice plants. However, they never overwinter in Japan, which means that only migratory hoppers are the initial source of hoppers infesting rice paddy fields.
Biotype assay of migrated planthoppers revealed that the origin of the immigrant insects is the northern part of Vietnam. The migration process consists of two steps. Firstly, planthoppers endemic to Vietnam move to China in early spring and multiply there for two or three generations. They then fly to Japan, transported by a low-level jet stream. The occurrence of these jet streams can be predicted by computerized programs analyzing data on wind speed and direction from 74 sites. This method is now used as the basis of a national forecasting system that covers the whole of Japan. The system also includes the monitoring of planthopper catches at more than 200 sites.
Pest Risk Analysis of Mealybugs on Orchids
Orchids have become a major commercial and export crop. They are a popular flower because of their unique shape, beautiful color and relatively long vase-life. Although many countries have great potential to develop orchid production, there is a widespread problem of mealybug (Pseudococcus microcircus). Mealybugs are already established in a number of tropical countries, where they are causing extensive damage to orchid production. Countries which intend to develop their orchid industry, and import new varieties as planting materials, should be very careful to avoid invasion by this pest.
In Indonesia, mealybugs are potentially a major exotic pest. Import restictions on orchid seedlings are already in place, in the hope of preventing their entry. Pest risk analysis of mealybugs is urgently needed, so that adequate plant quarantine measures can be implemented.
Example of Some Actual Quarantine Restrictions
Constraints to Imports of Fresh Fruit and Vegetables from the Pacific to Taiwan
Taiwan's warm, humid climate is favorable to the spread of pests. The island also imports large quantities of planting material, as well as agricultural produce. A number of regulations govern the importation of fruit, vegetables etc., in order to prevent the introduction of exotic pests. Participants at the meeting were very interested in the details of these regulations, and how they are applied in practice.
Precautionary rules cover a number of imported vegetables and fruits. There is a prohibition on imports of the underground portion of plants other than garlic, onion and Welsh onion from areas where the burrowing nematode (Radolphus similis) is known to occur. Although Papua New Guinea, Samoa, Australia and Solomon Islands are known to be infested with this pest, vegetables can be exported from these countries to Taiwan as long as they are free of soil and without the underground portion. However, there is a ban on imports of eggplant, tomato and other solanaceous plants from Australia, where blue tobacco mold exists. Imports of fresh mango are prohibited from Australia, Fiji, Papua New Guinea, and other areas infested with mango seed weevil and mango weevil. Apart from pineapple, coconut and green banana, all fresh fruits and vegetables from Australia must be treated by using approved quarantine procedures against Mediterranean fruit fly. Otherwise, imports of fresh fruits are generally admissible, and subject to inspection on arrival. Fruit consignments are inspected at the port of entry, and if they are found to be free of pests, they are released immediately.
Pest Risk Analysis is generally accepted as the principal strategy to make sure that plant quarantine standards are transparent and justified on a sound scientific basis. However, its application to individual pests will require great deal of further discussion, and further detailed work. Once this is done, PRA can be expected to remove unnecessary barriers to trade.
There is an urgent need for all countries to reach an equal level in plant quarantine, in terms of technology and equipment. An international network on quarantine pest monitoring is also needed, to meet the growing danger of exotic pest invasion as a result of growing international tourism and trade, and the long-distance migration of insect pests.
Two FFTC Training Courses on Plant Quarantine
First Training Course:
Date: June 17-20, 1996
Second Training Course:
Location: Suva, Fiji
Date: August 20-21, 1996
No. Participating Countries: 20 (Japan, ROC, New Zealand, American Samoa, Cook Islands, Fiji, Futuna, Guam, Kiribati, Marshall Islands, New Caledonia, Niue, Solomon Islands, Tokelau, Tonga, Vanuatu, Wallis, Westen Samoa)
No. Papers: 5 (plus hands-on training)
No. Participants: 39 (4 resource persons, 34 trainees)
Co-sponsors: Ministry of Primary Industries and Cooperatives, Fiji
South Pacific Commission
Food and Agriculture Organization (FAO), U.N.
List of Papers
1. Pest risk analysis in relation to sanitary and phytosanitary agreements- John Hedley2. Pest risk analysis of viral diseases of tropical fruits, and the need for a virus-free nursery system
- Hon-Ji Su
3. Long-distance migration of insect pests in relation to pest risk analysis
- Tomonari Watanabe
4. Pest risk analysis of Pseudococcus microcirculus McKenzie on orchids
- Justinus Soejitno
5. The present status of plant quarantine in Taiwan and quarantine constraints to fresh fruits and vegetables exported from the Pacific into Taiwan
- Sheng-Teh Lee
Index of Images
Figure 1 FFTC Has Had a Program to Send Good Used Microscopes from Japan to Quarantine Stations in the Pacific Which Lack Them.
Figure 2 Quarantine Inspection of Postal Materials, Japan
Figure 3 Pumpkin Imported into Japan from Pacific Island Nations
Figure 4 Inspecting Imported Green Vegetables for Pests and Disease.