1. Construction of Epidemiology Information Interchange System for Migratory Insect Pests in Asia Region: ASSESSMENT OF RICE PLANTHOPPER POPULATIONS AND VIRUSES in the PHILIPPINES
Genaro S. Rillon1, Cesjoy Carl B. Encarnacion1 and Jang-Kyun Seo2
1Crop Protection Division, Central Experiment Station (CES), Philippine Rice Research Institute (PhilRice), Maligaya, Science City of Muñoz, 3119 Nueva Ecija, Philippines
2Crop Protection Division, National Academy of Agricultural Science (NAAS), Rural Development Authority (RDA), Korea
*Report during AFACI Program Workshop on Food Crops. September 21, Siem Reap, Cambodia.

2. Introduction
The Philippines’ agriculture sector continues to play a pivotal role in the economy
More than 11 million Filipinos relied on agriculture for their livelihood in 2013, according to the Philippines Statistics Authority (PSA).
The palay, poultry and livestock industries were the key drivers of growth in 2013, and the segments continued to perform well in the first half of 2014.

3. However, from January to March 2016, agriculture posted a 4
However, from January to March 2016, agriculture posted a 4.53% drop in production due to prolonged dry spell and damages caused by Typhoons "Lando" and "Nona".
On the other hand, the crops subsector contracted by 8.55%. 

4. The new programs of the Department of Agriculture in the Philippines nowadays focused on making food available and affordable for Filipinos.
To make food available, farmers must produce enough for 105 million Filipinos in a country with a population growth of 1.9% every year, with special attention to rice which is our staple food.

5. However, in rice production, one of the recent constraints in the Philippines are rice planthoppers (RPH) such as brown planthopper (BPH), small brown planthopper (SBPH), and white-backed planthopper (WBPH)

6. They transmit viruses devastating to rice plants
They transmit viruses devastating to rice plants. For example, rice grassy stunt virus (RGSV) and rice ragged stunt virus (RRSV) are persistently transmitted by BPH
Rice black-streaked dwarf virus (RBSDV) and rice stripe virus (RSV) are spread by SBPH.

7. Recent studies showed that WBPH also can transmit a new virus, Southern rice black-streaked dwarf virus (SRBSDV or also known as RBSDV-2), which is currently problematic in Southern China and Northern Vietnam.

8. Too much feeding of planthoppers caused hopperburn or yellowing, browning and drying of plant.

9. In the Philippines, major planthopper outbreaks have not been reported after 1980s.
However, in the wet season of 2010, planthopper outbreaks have damaged about 6,700 ha in Iloilo and 40.3% of the area had significant yield losses (Catindig et. al., 2010).

10. In rice-based farming, farmers plant vegetables to provide another source of income for their family.
Among the important solanaceous crops they plant are tomato and hot pepper.
Tomato is one of the 43 major vegetable crops grown anytime of the year in the Philippines. It contributed 30% to 60% of the total value of vegetable production in the country.
Hot pepper is also an important crop contributing to vegetable industry.
However, the contribution of these crops to vegetable industry has decreased due to the incidence of viruses, insect pests, bacterial and fungal diseases including nematodes.

11. In tomato, viruses contribute the most to economic loss
In tomato, viruses contribute the most to economic loss. The tomato yellow leaf curl virus is considered the most important tomato virus disease in the Philippines and other Southeast Asian countries. Its occurrence in the Philippines has dramatically increased in recent years.
During episodes of heavy infection, almost % of the tomato plants can be infected resulting in 50-90% yield reduction. Sources of resistance have been identified but these are usually strain-specific.

12. In view of this potential problems, it is necessary to take close monitoring of RPH populations and damage including viral diseases in selected solanaceous crops.
The outputs of the project will contribute to the development of efficient management strategies for impending outbreaks in the Philippines.

13. Field survey results for rice planthoppers, rice viruses and plant species
Monitoring of planthoppers with light trap in PhilRice CES, Science City of Munoz, Nueva Ecija
Monitoring of RPH populations was conducted at PhilRice Central Experiment Station using light trap made by Everwell Corporation, Tokyo, Japan.
It has an attached 18-watts electric bulb at a height of 2 m from the ground.
Light trap at PhilRice CES, Science City of Munoz, Nueva Ecija.

14. The light was set up weekly and used to approximate numbers of planthoppers (BPH and WBPH) density.
Collected samples were brought to the laboratory for identification and counting.
The monitoring was conducted from January to June 2016.
Data collected were summarized, and expressed per week.

15. Result showed that the population of RPH had risen tremendously, there were about 9 and 33 times more planthoppers as compared in 2014 and 2015 respectively.
The highest number of BPH was recorded in March (45,814). More BPH than WBPH were trapped
WBPH followed the same patterns of populations although have lower populations as compared with BPH.
Change in population density of planthoppers collected from light trap at PhilRice Central Experiment Station, Science City of Munoz, Nueva Ecija

16. The contributing factors favoring the recent development of planthopper populations could be:
Higher use of inputs such as insecticide and fertilizer
Change in usage of variety
Cropping system

17. Monitoring of planthoppers using sticky traps in two sites located in PhilRice CES and Mabini, Sto. Domingo, Nueva Ecija
Monitoring of planthoppers in the field using sticky trap was conducted in two sites located in PhilRice CES and Mabini, Sto. Domingo, Nueva Ecija during the dry season of AFACI provided the sticky traps for sampling RPH.
Sticky trap used to sample rice
planthopper populations

18. Weekly monitoring by sticky trap started at ten days after transplanting until maturity of rice crop. In each sampling per week, sticky trapping was conducted at ten hills randomly selected per field. At each trapping spot, the sticky trap was placed between two plants.
The two plants were tapped three times to capture insects. Weekly monitoring in a single field consisted of three replications.
After sampling, the traps were brought to the laboratory for counting and recording the number of collected BPH and WBPH including spiders.

19. Highest number of RPH population was observed in March to April in PhilRice CES, Science City of Munoz and Mabini Sto. Domingo, Nueva Ecija.
More BPH was recorded as compared with WBPH. During the field samplings, spiders, coccinelids, mirids, and tiger beetles were commonly observed in the field.

20. During this season, planthopper populations were about 8 to 15 times higher as compared to those recorded in the previous year. More planthoppers were monitored in Mabini, Sto. Domingo as compared in Maligaya, Munoz, Nueva Ecija.
Even if there was high population of RPH in the field towards the reproductive phase of rice plants, injuries due to the insects were not observed in both sites.

21. The population patterns observed using sticky trap would indicate that RPH develops in the field and peaked towards the end or as the crop neared maturity.
Highest RPH populations coincided with the reproductive to ripening phases of rice plants in the field. Planthoppers prefer these phases of rice growth as they can get better nutrition around these stages.
In the latter rice growth stages, populations decreased because planthoppers usually emigrate when rice is maturing due to poor food conditions of host plants.

22. Damage Assessment
Hopperburn due to BPH and WBPH was assessed by estimating the percent infested area and the sum of ground covered by the patches within the sampling area.
Result of assessment showed that rice plant showing virus diseases transmitted by RPH and hopperburn were not observed in the selected sites.
However, during the 2016 dry season, planthoppers caused 10-15% hopperburn damage in about 2,000 hectares in Nueva Ecija. Most rice plants showing damage were at soft dough stage or about to be harvested. The observed hopperburn occurred when light trap catches were high.
Also, during the Farmers’ Field Day held in PhilRice last March 31 to April 1, 2016, aside from farmers from Nueva Ecija, participants coming from nearby provinces of Tarlac (Anao, La Paz, Victoria and Capas ) and Pampanga (Candaba) reported problems on hopperburn in their fields.

24. Although the damage is not in serious outbreak proportion, the continued observation of this hopperburn damage in the field would indicate the necessity to continuously monitor and analyze current scenario to prevent pest outbreak in the future.

25. Information on pesticide usage and levels
In study sites in Munoz and Sto. Domingo, Nueva Ecija, only minimal amount of insecticide was applied in the field as they only apply it when necessary.
Pesticide use reduction is one of many impacts of Integrated Pest Management (IPM) through farmer field schools (FFSs). The proportion of farmers who applied insecticide during the first 30 days after transplanting dropped from 68% to 20% after one year, and to 11% after two years (Heong et. al, 1995).
However, Litonjua et. al. (2014) reported recent results that farmers mainly applied pesticide to control pests and diseases. Farmers applied more pesticides when cropping intensity increased due most likely to higher incidence of pests.

26. Field survey results for vegetable insect pests and viruses
Pest assessment was conducted in tomato and hot pepper planted inside PhilRice CES.
The variety of tomato planted was Diamante while the variety of hot pepper was Django.
Monitoring by visual assessment was conducted from late part of 2015 to early part of 2016.

27. Tomato
The major damage recorded caused by insect pests in tomato were those caused by leafminer, leaf-feeding ladybird beetle, tomato fruitworm, cutworm and other defoliators.
The damage by leafminer characterized by many small blisters like tunnels or mines containing its larva was commonly observed during the pest monitoring
The feeding by scraping the surface of the leaves until it has been skeletonized of adults and larvae of the leaf-feeding ladybird beetle were very evident in the tomato plants.
Fruits infested by fruitworm was found at high infestation especially during fruit development to harvest, rendering many fruits non-marketable. In addition, holes on leaves caused by several other larvae of lepidopterans were also recorded.

28. Damping off, bacterial wilt, early and late blight diseases were constantly monitored.
Other damage observed which was occasionally problematic in tomato included blossom end rot. The primary symptom of this physiological disorder is characterized by dry rot with water-soaked appearance at the blossom end of the immature fruits. It later enlarges and turns into papery or leathery sunken brown to black rot upon infection of saprophytic fungi (secondary symptom). Fruits with end rots are non– marketable also.

29. Hot pepper
Among the common insect pests monitored in pepper were mites, whiteflies, fruitworm and aphids
The excessive direct feeding of high populations of mites caused leaves of pepper to become distorted and curled downwards. Young leaves were observed cupped downward and narrower than normal.
Many whiteflies were noted that attacked by sucking the sap of pepper leaves. It also acts as a vector of tomato yellow leaf curl virus that causes yellowing and curling of leaves resulting in stunted plants with aborted flower and fewer fruits.
Some damage due to fruitworm were also observed, evident with hole at the base of the fruit that contained frass and decay, often the caterpillar can be seen inside the fruit.

30. The foliar disease powdery mildew was observed consistently during monitoring. Powdery mildew affected leaves have light-green to bright-yellow blotches that appeared on upper surfaces of leaves. Infected areas later turn necrotic, curl upward and a powdery, white growth was visible on the underside of leaves. The symptoms of the disease usually progress from older to younger leaves.
Important diseases like leaf spot and pepper mosaic virus were also observed.
Other damage observed was sunscald. Suncald is damage when fruits are exposed to direct sunlight, first appear as wrinkled area that can be soft and lighter in color than surrounding tissue. This area later collapses and turns white and paper-like.

31. Information on pesticide usage and levels
Vegetable production in the country is usually associated with heavy use of pesticides as farmers still rely on the use of synthetic pesticides to prevent yield loss which often leads to misuse or overuse of these chemicals, incurs significant economic costs and poses negative health and environmental impacts in the long run.
This is true in the production of tomato, eggplant, hot pepper, ampalaya and other high value vegetables.
An example of typical massive use of pesticide is in eggplant production. Results from interview of eggplant farmers in Northern Philippines showed that they sprayed from 5 to 115 li of insecticide for the 5-6 month duration of production (Francisco, 2009).

32. 2016 project outcomes
Data available on the occurrence of RPH populations and damage
Data on major pests in tomato and pepper documented
Awareness of the future problem in rice production, poster paper presentations
47th Pest Management Council of the Philippines (PMCP) Anniversary & Scientific Conference. March 8-11, Villa Caceres Hotel, Naga City, Camarines Sur, Philippines
29th National Rice R&D Conference. September 7-8, PhilRice CES, Science City of Munoz. Nueva Ecija.
12th Agriculture and Fisheries Technology Forum and Product Exhibition. August 11 to 14, Mandaluyong City, Philippines.

33. 2017 project plan
Continue the close monitoring of planthoppers and associated damage to reduce vulnerability of rice to RPH infestations
Determine the factors that will cause possible outbreaks that may cause significant rice yield losses
Including those of important solanaceous crops such as tomato and hot pepper.

34. DISCUSSION AND Recommendation
Continue strong collaboration that is very essential for the improved management of RPH and associated viruses in the region;
Continuous generation of information to strengthen current management strategies to address present pest problem;
Assess current practices of farmers contributing to the increased RPH problems in the region;
Capacity building and knowledge management skills for partner countries through trainings on new pest management techniques and other skills such as modelling of insect dynamics and associated diseases, forecasting and diagnostic tools to prevent pest outbreaks; and
At national level, IPM implementation must be sustained and followed up with programs to support training of farmers to acquire necessary skills to be better IPM practitioners. The program must ensure the diffusion of new pest management knowledge and information that could lead in the achievement of the main goal of establishing IPM as standard practice in pest management.

35. Thank you