Protecting crops from invasive species | Sunday Observer

Protecting crops from invasive species

The Fall Army Worm (FAW) has invaded maize cultivation and over 43,000 hectares have already been infested by the pest which has a greater affinity for the crop, besides being able to live in about 100 plant species.

The ability of the adult moth of the caterpillar to have a single wind-aided flight of about 80-100 km is alarming. This has given a perfect setting for the pest to be invasive during a short period over a wide land area, Professor, Weed Science and Chairman Board of Study in Crop Science, Postgraduate Institute of Agriculture, University of Peradeniya, Buddhi Marambe said in an interview with the Business Observer.

Excerpts:

Q: How serious is the problem and what are its repercussions on the agriculture sector?


Prof. Buddhi Marambe

A: The Fall Army Worm (Sena Dalambuwa; Scientific name: Spodoptera frugiperda) has a wide range of host species, with maize (corn) being the preferred host. In Sri Lanka, maize is cultivated mainly during the Maha season (75,000-80,000 ha) and about 9,000-10,000 ha during the Yala season. During this Maha season (2018/2019), over 50 percent of the cultivation (43,000 hectares) has been infested by the pest.

More than 95% of the maize cultivation comprises imported hybrids.

The pest has a greater affinity for maize but can live in about 100 plant species. The adult moth of the caterpillar has a single wind-aided flight of about 80-100 km is alarming.

This has given a perfect setting for the pest to be invasive during a short period over a wide land area. The pest has all the characteristics of being invasive, such as short life cycle (about 60 days), multiple egg-laying cycles (about five times during the 10-21 days life span of the moth, laying 50-200 eggs).

The moth can even lay 1,500-2,000 eggs during its life cycle. The pest lives in many plant hosts and the adult moth travels long distances to lay eggs.

The pest has started to have a major impact on the maize crop, which is cultivated mainly to provide part of the animal feed. Loss of the maize crop yield will affect farmer income, result in loss of investment and loss of foreign exchange due to import of maize to support industries such as poultry.

With over 100 plant species being recorded globally as host plants, including major crops and some troublesome weeds, the situation has become critical in terms of eradicating the pest. With all past experiences and evidence from other affected countries, the pest has landed in Sri Lanka to stay, unless proper control measures are adopted, even to live with it in the foreseeable future.

Q: Was the country not adequately geared with quarantine methods to prevent the invasion of the species?

A: The pest originated in the Central American region and has been a problem to many crop cultivations in the tropical America for several decades. It was reported in Central Africa in 2016 followed by Yemen, and in India in 2018 (March/April).

Upon receipt of the information on the arrival of this devastating pest in India, the Department of Agriculture (DoA) of Sri Lanka launched an awareness program in September 2018 to alert the farming community and the public on its probable entry to Sri Lanka.

This prompted the DoA to initiate action which was later expanded with the news of the pest landing in Sri Lanka in early October.

Sri Lanka has good plant and animal quarantine services at the legal ports of entry (by sea and air) to the country. The National Plant Quarantine Service (NPQS), for example, is fully geared to detect alien organisms, especially, pests of this nature, through their rigorous protocols. However, in some cases, lack of skilled human resources could delay the screening process. All planting materials legally brought to the country by the government or the private sector goes through this rigorous screening process. Understanding the biological cycle of the pest indicates little or no chances that it entered Sri Lanka through planting materials imported to Sri Lanka.

Based on available information, entry of the pest to Sri Lanka due to the weaknesses of the quarantine process is out of the question. There may be many other ways for the pest to enter, such as through aerial routes owing to its capacity to fly long distances, which I understand to be highly probable.

I hear that there are lots of doubts among people including politicians, who still point the finger at the quarantine process, An official communications from the DoA, after a thorough review of the situation, will help clear the doubts created in people’s mind on the entry of pests. The crucial issue is that the pest has already invaded, and further invasion has to be stopped at any cost.

Q: What urgent measures do you propose to stop the spread of the crop-killer and be prepared for the future?

A: Destroying one caterpillar will help get rid of over 2,000 new caterpillars that would have a devastating effects on our agriculture. The pupae of the pest lives in the soil before giving birth to the moth, which usually emerge in the night to start its flight to lay eggs again at a distance.

While understanding how critical the situation is, the DoA and the Ministry of Agriculture have launched a program focusing on short, medium and long-term objectives. Evidence indicates that the pest population density has gone beyond the imagination of scientists.

None of us expected the spread of this pest to be so rapid. This is unfortunate, as we were unable to support the farming community and policymakers to minimise the damage at the beginning, despite some awareness programs being conducted.

However, we have to deal with the problem, which is probably the most damaging biological invasion that the country has experienced during the recent past.

The science behind the control of such alien invasives, especially when the pest is mobile and population densities have reached explosive stages, is to bring down the population densities to a manageable size in the short-run through shock treatment. This may be by applying effective agro-chemicals and destroying affected crop cultivations by burning. Both seem to be difficult under Sri Lankan conditions.

The ban or severe restrictions imposed on effective pesticides (which are also more mammalian toxic and should be used with precautions and under supervision) such as monocrotophos, dimethoate and carbofuran, and the reluctance of farmers to burn the cultivated land (which is natural due to the investments made) have hampered the efforts to a great extent.

However, an integrated pest management approach has been launched quite correctly by the DoA with the help of all stakeholders, to use five pesticides that could generally kill Spodoptera spp., coupled with use of all techniques have yielded fruitful results in many cases.

The five pesticides are those containing the active ingredients Spinetoram, Spinosad, Emmamectin benzoate, Chlorantranoprole, and a mixture of Chroantraniprole and Thiomexam. These pesticides have been provided at 50% of the cost to farmers to curtail the problem to the best possible extent.

A better option would have been to bring down the population densities by one time controlled-application of more effective systemic pesticides, such as carbofuran, at early stages of plant growth (where it will last in the plant for less than 30 days) even by relaxing the regulations imposed on their import and use for a very limited period and by allowing the government machinery to apply them in practice, and to use other techniques in conjunction with it.

In India, pest control strategies include such highly effective pesticides. However, the fear in the people’s mind regarding such pesticides is forcing the authorities to put off taking such decisions.

We have experienced taking a poor decision without evidence, on the import and use of glyphosate and paid the price.

The decision has now been revoked and the product is now allowed to be imported and distributed only to tea and rubber plantations by the government arm (i.e. Ceypetco).

A similar option is advisable in this situation as well, removing other assumed worries that the private sector (multi-nationals as some would like to call them) will exploit the situation to make a quick buck.

Continuous scouting to monitor and hand pick caterpillars, looking for natural enemies, use of pheromone traps to catch the male moths (about 20,000 such traps have been ordered at present), adopting best practices for responsible use of pesticides, search for effective pesticide products and novel technologies from other countries to control the pest, use of traditional technologies and different concoctions proposed by the farming community at various locations are some of the short term techniques that can be used.

Currently, the focus is on the maize crop. However, we should never forget that the pest lays its eggs on weeds as well. Keeping the field weed free will also help reduce the pest population densities, which is crucial.

The use of varios mixtures of plant extracts developed by the farming community has been the talk of the town with claims for their efficacy. This is a welcome move and I see how important the matter is for people and their interest on this national issue.

The DoA should conduct formal trials to confirm their efficacy. However, people should be encouraged to use whatever technique possible to minimise the spread of the pest.

I also hear lots of claims on toxin-free (wasa wisa nathi) products - to kill the pest. If such plant-based product kills a pest that means toxins are at work. This is not to discourage people who have inventions and intervention. But the reality. Whether it is plant based or not, once the target organism is affected, then there is a toxic substance that has worked out (except for example, drowning in water).

Farmers should never neglect their land if the Fall Army Worm has attacked and start assuming that nothing can be done to control the pest. Such lands would be breeding grounds for the pest and the plants should be burned at the government’s cost. The fields that are heavily infested and farmers willing to destroy the crop should be compensated.

The institutes in the field of agriculture, including the Faculties of Agriculture at universities should be in the forefront in conducting research and surveys to identify any plant species or varieties of a given crop that the pest has not attached. Use of low amounts of fertiliser would also make the insect pest less interested in attacking the plant due to the low succulent nature. We need field observations and some research on this.

These will be useful in determining the future course of action in terms of crop rotation and mixed cropping to safeguard the food security of the country.

Use of biological control either by identifying natural enemies from our ecosystems or use of host-specific exotic biological agents or bio-pesticides are important areas to be explored quickly. There are many in literature and used in practice in other countries.

The Ministry of Agriculture and the DoA should immediately enter into agreements with international institutions/organisations to have access to such technologies to bring in species-specific biocontrol agents and bio-pesticides to have the pest controlled in the long run.

A major mistake by some in the recent past was to transport fresh parts of the maize plant long distances to be used as animal feed. This added fuel to fire by further aggravating the spread of the pest. On-site silage making (poly-silage or silage bales) would be better options. Government departments such as the NLDB should be provided with facilities to do so while obtaining the services of the private sector.

Many technologies, apart from what is listed above have been used by many countries to control the major pest of agriculture. Bt corn (Genetically Engineered - GM crop) has been suggested by many in other countries as the best solution. However, Sri Lanka does not allow the entry of GM crops. Hence, we need to look for alternatives, unless we start revising the previous decisions made. However, such changes should be carefully analysed with the support of experts before taking a decision.

Community participation is essential to find a long-term sustainable solution for issues of such nature. Continuous education and monitoring will play a crucial role at all times to protect our agriculture and ensure food security.

We still do not know what is in store for us in the future. Maize, which is attacked most by the Sena Caterpillar is being harvested. The next crop of maize will be planted in the Yala season. Soon after harvest, the stubble should be burnt, soil should be tilled, and weeds should be controlled to make sure the growth stages of the pest will not transform it into an adult. Though the Yala season will have a much less cultivated extent of maize than in the Maha, we may have to rethink cultivating this crop in a scattered manner. Timely cultivation in an area will help manage the pest population easily. We should also look into the country’s need for maize, especially for animal feed, in the decision-making process especially in crop rotation.

Even now, there are many claims that the pest has invaded other crops such as sugarcane.

Reports also say that the pest is found in other crops such as vegetables and a report from one location states that the pest was found on the rice plant, though there was no confirmation on the impact (whether it feeds on the rice plant - I hope and pray that this will never happen in Sri Lanka).

Policy and regulations matter a lot in situations of this nature. The Biodiversity Secretariat of the Ministry of Mahaweli Development and Environment, has already adopted a National Policy on Invasive Species in Sri Lanka - Strategies and Action Plan.

This was launched by President Maithripala Sirisena on June 5 (World Environment Day) 2016. The new Invasive Alien Species Control Act is being drafted. Work started with the approval of the Cabinet of Ministers in 2017. Such efforts will prevent the entry and also control the spread of such invasive species in the future.

Q: Has the damage to crops been estimated?

A: As for maize, the yield loss due to pest damage has been estimated at between 5-25%. A more realistic estimate would reach us after harvesting. The caterpillar has preferred the tender parts of the maize plant, including emerging and young leaves, and the young cob (Kiri Karal - harvested 65-70 days after planting for human consumption, sold by the roadsides). The pest has failed to have a significant impact on the mature cobs and as per our observation, only the upper part of the mature cob is damaged by the pest.

The estimates of damage on other crops as claimed by some farmers are still being gathered.

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FAO shares info on combating ‘Sena’ with agri ministry

The Fall Army Worm (FAW) or Spodoptera frugiperda has been reported in all major maize growing areas in Sri Lanka and is also affecting sugarcane cultivation. There is a growing concern that it may affect other crops, including rice.

Native to the Americas, FAW was first detected in Central and Western Africa in early 2016 and quickly spread across virtually all of Sub-Saharan Africa. In July 2018, it was confirmed in India in Karnataka state and since then it has been found in seven other States including Tamil Nadu. FAW was also detected in Yemen in 2018 and has now reached Sri Lanka.

In the absence of natural control or good management, the FAW can cause significant damage to crops and affect the livelihoods of farmers. Once established in a new area, FAW cannot be practically eradicated. It becomes one more pest that farmers need to learn about and manage.

Raising awareness about the FAW and understanding lessons learned from other parts of the world, including available management options are essential first steps in responding adequately to the situation in Sri Lanka.

The Food and Agriculture Organisation of the United Nations (FAO) has shared background information with the Ministry of Agriculture and the Department of Agriculture on the biology and ecology of the FAW, on how to scout the pest, and on management strategies. The information includes a range of options available that don’t use hazardous pesticides, minimise the use of chemical pesticides, and educate policy makers and farmers about agro-ecological approaches used by smallholder farmers in Latin America and being tested by smallholders in Africa and India as well.

Field guides and Guidance Notes about FAW Integrated Pest Management (IPM) strategies developed by responding to the outbreak in Africa, particularly by implementing Farmer Field Schools, have been disseminated to the Ministry of Agriculture and the Department of Agriculture in Sri Lanka. Tools such as the Fall Armyworm Monitoring and Early Warning System (FAMEWS) mobile app developed by FAO to collect information on FAW population levels by field scouting and/or use of pheromone traps have been shared.

FAMEWS supports all stages of FAW management: to identify the pest, monitor the level of infestation to map its spread to make decisions, as well as to learn about the important natural enemies and the measures that are most effective in managing it.

FAO remains committed to supporting the concerned national authorities to manage the pest and to protect the Sri Lankan farmer community’s livelihoods. The Organisation will continue to monitor the situation in Sri Lanka and provide any technical assistance/expertise requested by the Government. 

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