Construction of Epidemiology Information Interchange System for Migratory Disease and Insect Pests in Asia Region (AFACI-IPM):

Monitoring and Field Survey on Rice Planthoppers & Viruses of Vegetables

Dr. Prem Nidhi Sharma

Entomology DivisionNepal Agricultural Research Council (NARC), Nepal

Email: premnidhi@yahoo.com

Introduction

Asia region grows wide range of cereals, pulses, fruits and vegetables to feed the huge population of the world. However several insect pests and diseases are the major threats to stable production of agriculture in the region. With the aim to strengthen the increased food productivity in Asia, Rural Development Administration (RDA)-Korea has developed several Asian Food & Agriculture Cooperation Initiative (AFACI) regional projects. The “Construction of Epidemiology Information Interchange System for Migratory Disease and Insect Pests in Asia Region (IPM)” is one of the AFACI regional projects leaded by RDA Korea. The main goal of the AFACI IPM project is ‘Establishment of an international cooperative network for the best management of migrating rice planthoppers and associated rice viruses and development of field application kits for the accurate examination of their incidence and analysis of genetic diversity of planthopper populations and information exchange on the insect pests and viruses in vegetable crops’. Several Asian countries are the members of this project to work jointly to manage the problems of rice planthoppers and associated viruses of rice and vegetable diseases transmitted by vector insects. Nepal joined this project as a member country since August 2011. This project has now completed the 3 rd

year (July 2015 - June 2016) of 2nd phase (July 2013 – June 2016).

Rice planthoppers (RPHs) particularly the brown planthopper (BPH) (Nilaparvata lugens Stål), white back planthopper (WBPH) (Sogatella furcifera) and smaller brown planthopper (SBPH) (Laodelphax striatellus) are the major threats to cause significant losses in rice production in Asia. RPHs damage rice plants directly by sucking the phloem sap. As a result, in case of severe damage, rice plants dry up which is referred to ‘hopper burn’. Indirectly, they damage acting as vectors by transmitting virus diseases of rice such as rice grassy stunt virus (RGSV) and rice ragged stunt virus (RRSV) transmitted by BPH, rice black-streaked dwarf virus (RBSDV) and rice strip virus (RSV) transmitted by SBPH, and Southern rice black-streaked dwarf virus (SRBSDV or also known as RBSDV-2) transmitted by WBPH.

Both BPH and WBPH are simultaneously threatening the rice production in Nepal. SBPH is however not reported yet in the country. These insects were formerly the secondary pests but nowadays they become the major pests of rice particularly in Terai region of Nepal (Manandhar, 1999; Sharma et al., 2013, Pokhrel et al., 1998-1999). Farmers generally use broad-spectrum insecticides as a quick, cheap and easy means of insect control. However, excessive use of chemical pesticides has caused negative effects such as insect resurgence, destruction of natural enemies, and development of pesticide resistance in insect populations including in BPH and WBPH. As a result, serious and frequent outbreaks of BPH and WBPH have been observed in different parts of Nepal every year. Planthoppers have

recently become more widespread in the eastern to western parts of Terai region and also in river basin areas of hilly regions & surrounding of Kathmandu valley in Nepal (Sharma et al., 2013; Sharma et al., 2014). Severe form of RPH outbreaks might occur in any time in future in Nepal. Management of RPH by close monitoring and using preventive measures and IPM tactics including searching and development of resistant varieties is urgently needed.

The Entomology Division and Plant Pathology Division under Nepal Agricultural Research Council (NARC) are the two national organizations involving in research activities related to management of planthoppers and associated viruses of rice as well as diseases of vegetables caused by vector insects through the AFACI-IPM project. The monitoring of RPH and associated viruses and field survey on virus diseases of vegetables caused by vector insects are the main activities of the project. The AFACI-IPM project has now completed the 3 rd year (July 2015 – June 2016) of 2nd phase (July 2013 – June 2016). This report provides here the progress and achievements of 3rd year (July 2015 – June 2016) of 2nd phase. In addition, future plan are suggested to continue the project.

General information on agriculture statisticsSince Nepal has diverse geographic/climatic conditions large number of diverse crops can be grown from low plain-region (60 masl) to high mountain-region (1500 masl) (Terai, Hills & Mountain regions) - subtropical to temperate climates. Cereals, pulses, vegetables and fruits are the major agricultural commodities to grow in Nepal. Rice, wheat, maize, millet, barley and buckwheat are the cereal crops. Of which, rice, maize & wheat are the three major crops; rice ranks first and is the main diet of Nepalese people. Lentil, chick pea, pigeon pea, black gram, soybean, grass pea, horse gram are the major pulses. Oilseed, potato, sugarcane, tobacco, jute, cotton are the cash crops. Tea, coffee, cardamom, ginger, chilli, garlic, turmeric, cocoon, honey are the major commercial exportable commodities. Mango, litchi, banana, apple, orange are the major fruits. Many seasonal vegetable crops can be grown year round.

Table i. General information on agriculture statistics (ABPSD, 2013/2014)Area (ha) Production (Mt) Yield (Kg/ha)

Cereal crops 3480052 9562680 2748Cash crops 516860 6341782Pulses 328738 352473 1072Fruits 110086 965044 8766Vegetables 254932 3421035 13419Commercial crops 78821 451532Cocoon 38.5Honey 1650Mushroom 1675

Table . ii) Region wise area, production, and productivity of rice (ABPSD, 2013/2014)

Area (ha) Production (Mt) Yield (Kg/ha)Mountain 61620 149565 2427Hills 409398 1321941 3229Terai 1015933 3575541 3519Nepal 1486951 5047047 3394 Region wise area under irrigated & un-irrigated, improved & local rice in percentage

Area Irrigated Un-irrigated Improved LocalMountain 4.14 43.81 56.19 92.25 7.75Hills 27.53 47.28 52.72 86.38 13.62Terai 68.32 71.82 28.18 94.95 5.05Nepal 100 63.9 36.1 92.48 7.52

Rice varieties A total of 74 rice varieties & hybrids are released & registered. for various altitudes- for Terai/plain, hills and mountain regions; for irrigated, un-irrigated, rain fed, spring and rainy conditions (K.D., 2071).

Table-iii. The total 74 rice varieties and hybrids released and registered in NepalRainy season rice

Taichung-176, Chainung-242, Tainan-1, Chainan -2, Masuli, Janaki, Sabitri, Himali, Kanchan, Khumal-3, Khumal-4, Makawanpur-1, Ghaiya-2, Palung-2, Khumal-5, Khumal-7, Khumal-9, Chhomrong, Radha-7, Radhakrishna-9, Radha-4, Radha-11, Radha-12, Machhapuchhre-3, Khumal-6, Rampur Masuli, Chandannath-1, Chandannath-3, Manjusri-2, Khumal-11, Loktantra, Mithila, Ram, Barkhe 3004, Pokhreli Jethobudho, Khumal-8, Sunaulosugandha, Ghaiya-1, Lalka Basmati, Hardinath-2, Tarahara-1, DY18, DY28, DY69, Khumal-10, Khumal-13, Sukhkha Dhan-1, Sukhkha Dhan-2, Sukhkha Dhan-3, Barkhe-2014, Swarna sub-1, Barkhe-1027, Saba Masuli sub-1, Tara, Suraj, Prithibi, Araij-6444, P.H.B.-71, U.S.-312, Champion, Raja, R.H.-257, Gorakhnath-509, Loknath-505, P.A.C.-801, Reshma-786, Baisali

Spring season rice CH-45, Bindeswari, Chaite-2, Chaite-4, Chaite-6, Hardinath-1

Project results(a) Monitoring of RPHs Monitoring of RPHs was conducted in two project locations, at Bhandara in Chitwan and at NRRP-Hardinath in Dhanusha. The yellow sticky trap and light trap were used as tools for monitoring of RPHs (figure 1). A light trap was installed in each project location nearer the rice fields. Light trap data was taken daily during whole rice growing period of each season. Yellow sticky trap data was taken weekly from 10 days of transplanting of rice until to harvesting of rice. Two crops of rice are grown in location 1 (Bhandara) - spring season rice (Chaite Dhan) & main season rice (Barkhe Dhan). Only main season rice is grown in location 2 (NRRP-Hardinath). The monitoring results of rice insects of both locations have been mentioned hereunder.

Figure 1. The light trap (left) and yellow sticky trap (right) were the tools for monitoring of RPH including the major insects of rice.

Figure 2. Left: Weekly count of BPH, WBPH & Spiders on yellow sticky trap in main season rice at Padariya, Bhandara, Chitwan. Right: Light trap catch of pest insects (average number) of main season rice at Padariya, Bhandara, Chitwan. 2015.

In main season rice at Padariya of Chitwan in 2015, according to field collection data, appearance of RPH was initiated on July 13 and its number was reached high on September 29 at maturation stage (Figure 2, left). Light trap data showed that incidence of RPH was high in 2nd half of September and first week of October in main season rice at Padariya in 2015 (figure 2, right). In main season rice at NRRP-Hardinath in Dhanusha in 2015, based on field collection data, appearance of RPH was initiated from the beginning of August and its number reached at peak on September 27 and the number was decreased low at the end of November (Figure 3, left). Based on light trap data, higher number of RPH was noticed in September & October (figure 3, right).

Figure 3. Left: Weekly count of BPH, WBPH & Spiders on yellow sticky trap in main season rice at NRRP Hardinath, Baniniya, Dhanusha. Right: Light trap catch of pest insects (average number) in main season rice at NRRP Hardinath, Baniniya, Dhanusha. 2015.

Figure 4. Left: Weekly count of BPH, WBPH & Spiders on yellow sticky trap in spring season rice at Padariya, Bhandara, Chitwan. Right: Light trap catch of pest insects (average number) of spring season rice at Padariya, Bhandara, Chitwan. 2016.

In spring season rice at Padariya of Chitwan in 2016, according to yellow sticky trap data, appearance of RPH was initiated on April 13 and its number was reached at peak on May 11 and then the number was gradually decreased in June at harvesting time of rice (figure 4, left). According to light trap data, incidence of BPH was higher in second half May & in June; and incidence of WBPH was higher in June (figure 4, right).

(b) Field survey reports on rice plant hoppers and vegetable viruses

Field survey of RPH and vegetable viruses was performed in consequent dates in east Chitwan in 2015/2016 (2072/2073). The survey reports are mentioned hereunder.

Field visit on July 31, 2015 (4/15, 2072) at Bhandara, East Chitwan : Rice plants (Sabitri variety) of main season rice were at maximum tillering phase. Population of RPH was noticed thin. Number of WBPH was noticed higher as compared to BPH. RPH-nymphs were observed of different stages (1-5 instar).

Field visit on September 12, 2015 (5/26, 2072) at Bhandara, East Chitwan: Rice plants were at booting to ear emerging phases. Higher number of WBPH was observed than of BPH. But in a rice field at Gadauli, higher number of BPH was noticed. Some rice fields at Dudgnau were seriously infested by RPH. Some farmers had used Sumo (Imidacloprid 17.8 SL) and Judwaa (Chlorpyriphos 50% + Cypermethrin 5% EC) insecticides to control RPH. But according to farmers, these insecticides were ineffective to control RPH.

Field visit on October 6, 2015 (6/19, 2072) at Bhandara, Chitwan: Rice plants were at maturity to harvesting stages. Harvesting of rice was just initiated for early maturing varieties and early planted rice. Sabitri rice was grown by most of farmers in Chitwan which has not harvested yet. High incidence of BPH was observed in most of the places of east Chitwan - Padariya, Dhamaura, Piple-7 and Piple-9.

A rice field that was nearly hopper burned by BPH was monitored with yellow sticky card at Padariya. High density of BPH was noticed in the hopper burned rice field. Thirty five adult BPH, fifteen 3-5 instars BPH, and ten 1-2 instars BPH were observed on yellow sticky card per 5 hills in the hopper burned rice field. An insecticide ‘REAL MIDA’ (Imidachloprid 200g/L SL, 10 ml/16L) was applied at heading stage of rice in the hopper burned rice field but no effect of the applied insecticide was observed to kill the BPH.

A rice field at Piple-7 was seriously damaged by BPH (Photo A, below). Sabitri rice was at harvesting stage in the field. Farmer had applied various insecticides, 1 time before and 3 times after panicle initiation of rice in the damaged field; however no effect of insecticides was observed in the field to control BPH. The various insecticides applied by farmer in the field were: Admire 70 WG (systemic insecticide), AVER TOP (Chloropyriphos - 50% w/w, Cypermethrin - 5% w/w, and Adjuvent – 45% w/w = 100%), Theoron (Lamda Cyhalothrin 5% EC) and Sumo (Imidachloprid 17.8% SL, systemic insecticide). A farmer, in an adjoining field, was harvesting her rice crop earlier than the normal time of harvesting due to the fear of further damage of rice by BPH (Photo B, below).

Some rice fields (1 ha) of a farmer that were hopper burned by BPH at Piple-9 (Photo C, above). The rice crop was at maturity stage in the fields. A rice cultivar ‘Katarni’ was grown by the farmer in his fields which was almost hopper burned due to BPH. High density of BPH was observed in the hopper burned rice fields - 180 BPH (150 male, 10 female and 20 nymphs) per 5 hills of rice on a yellow sticky card. The farmer had applied an insecticide [Carbine (Chloropyriphos 50% + Cypermethrin 5% EC)] 5 times in his fields at one month interval after 15 days of transplanting of rice; however there was no effect of insecticide to protect rice from hopper burn.

Field visit on April 5, 2016 (12/23, 2072) at Bhandara, Chitwann:

Rice and vegetable fields were visited at various places surroundings of Bhandara. Transplanting of spring rice (Chaite Dhan) was just initiated at Padariya. Rice was transplanted 12 days earlier than of Padariya. Rice fields of Rapti Na.Pa.-2, 3, and 4 were inspected. No RPH was noticed in the rice fields.

Vegetable fields were visited at various places - Piple, Jhurjhure and Purbari. Virus infected symptom was observed in some capsicum/chilli plants (Photo A, below). Three leaf samples of 3 infected individual plants of 2 different sites (Purbari and Jhurjhure) were kept in RNA Later and were sent to RDA Korea (to Dr Jang-Kyun Seo, Crop Protection Div., NAAS) for virus detection. RT-PCR analysis detected both pepper mottle virus (PepMoV) & cucumber mosaic virus (CMV) in all the 3 samples (Photo B, below). The RT-PCR analysis were performed to detect for 7 pepper viruses – PepMoV, CMV, broad bean wilt virus 2 (BBWV2), tomato spotted wilt virus (TSWV), potato virus Y (PVY), beet western yellows virus (BWYV) and pepper mild mottle Virus (PMMoV).

Field visit on May 12, 2016 (1/30, 2073) at Bhandara, Chitwann: Rice plants of spring rice (Chite rice) were at maximum tillering phage. The Harinath-1442 variety was planted by most of farmers. Significant number of BPH and WBPH were noticed in the rice fields of Padariya, Beldiya, Jhurjhure, Hardi and Birendranagar when monitored with yellow sticky traps (table below). Sampling of RPH was done in ten spots in each field by keeping yellow sticky trap in between two hills of rice. Number of WBPH was higher than of BPH in the rice fields. Considerable number of spiders was noticed in the rice fields.

Place BPH WBPH Total RPH SpiderPadariya 77 122 199 1Beldiya 36 150 186 6Jhurjhure 61 66 127 6Hardi 67 67 134 11Birendranagar 68 67 135 3

Field visit on June 4-5, 2016 (2/22-23, 2073) at Bhandara, Chitwan: Spring rice (Chaite Dhan) at Khairahani-1, Piple-5 and Dhamaura were inspected. The Hardinath-1 (BG-1442) variety was grown by most farmers. Rice plants were at early heading to maturity stages. According to farmers, rice crops will be harvested by 24 – 29 of June. Density of RPH was at peak; however no hopper burn was noticed in the rice fields in east Chitwan. RPHs were monitored by yellow sticky trap. Two rice fields were monitored in each place, field-1 & field-2 (table below). Sampling of RPH was done in ten spots in each field by tapping two hills keeping the yellow sticky trap in between the two hills. The BPH and WBPH were seen in mixture in rice fields with higher density of WBPH. Due to the presence of significant number of natural enemies the number of RPH could not be increased high to cause economic damage to rice plants.

Place BPH WBPH Total RPH SpidersKhairani-1, field-1 3 13 16 11Khairani-1, field-2 6 17 23 5Piple-5, field-1 25 66 91 5Piple-5, field-2 12 29 42 9Dhamaura, field-1 18 56 74 9

Dhamaura, field-2 0 9 9 4

Field visit on June 22-24, 2016 (3/8-10, 2073) at Bhandara, Chitwan: Monitoring of RPHs were performed at - Padariya, Birendranagar, Hardi and Gadeuli. Rice plants were at harvesting stage. Density of RPHs was decreased in fields due to continuous heavy rain during the visit. RPHs were monitored keeping yellow sticky card in between two plants and tapping the plants, in 10 spots at 10 steps interval in every field in every place. No hopper burn was noticed in the places during the visit. The monitoring data are shown in the table below.

Place BPH WBPH Total RPH SpiderPadariya, field 1 30 10 40 27Padariya, field 2 22 3 25 12Birendranagar 25 28 53 8Hardi 21 16 37 10Gadauli field 1 12 4 16 8Gadauli field 2 5 3 8 11

Field observation of a zucchini research trial on June 6, 2016 (2/24, 2073) at Khumaltar, Lalitpur:

The research trial of zucchini plants infected by virus at Khumaltar, Lalitpur: (A) Collection of virus infected leaf samples in RNA Later to send to RDA Korea for virus detection. (B) A virus infected zucchini plant. (C) A plant pathologist is observing the infected plants. (D) A virus infected zucchini fruit.

(c) Mass rearing of BPH and identification of BPH resistant rice varieties

BPH resistant rice varieties were identified by using 1-9 scale of damage scoring method (IRRI, 1998) at Entomology Division, Khumaltar. The identified BPH resistant varieties were: NR 601-9 was Resistant (3); IET 16775, Sukhadhan-4 & Tarahara-1 were Moderately Resistant (4); Ram Dhan was Moderately Susceptible.

(d) A training/workshop was organized to target groups

A training/workshop on AFACI-IPM was organized to entomologists and plant protection personnel of Research, Extension & Education at Entomology Division, Khumaltar on October 15-16, 2015 (Photo A, below).

(e) A stereo microscope (research model) was purchased by Entomology Division for the purpose to capture real image of insects for insect identification; funded by RDA-Korea (Photo B, below).

Project Achievements/Out Comes

Important species of RPH known – BPH & WBPH Incidence pattern of RPH known

Incidence patterns of RPH was known for main (2015) and spring season (2016) rice of Chitwan and main season rice of Dhanusha. This information is useful to predict incidence of RPH and apply suitable protection measures to RPH at appropriate time.

The occurrence of severe form of outbreaks of RPH known

The occurrence of severe out breaks of RPH for main season rice (2015) of Chitwan was known. This information is helpful to take precaution to protect rice from possible severe outbreaks of RPH in future.

Viruses of vegetable crops identified

Both pepper mottle virus (PepMoV) & cucumber mosaic virus (CMV) simultaneously identified in capsicum/chilli plants in east Chitwan of Nepal by RT-PCR analysis conducted at Crop Protection Division, NAAS, RDA Korea.

Resistant varieties of rice identified to BPH Target groups got knowledge on AFACI-IPM A research model stereo microscope purchased for the purpose to capture real image of

insects for insect identification; funded by RDA-Korea.

Future plan/Way forward

• Continue & strength the monitoring works for RPH & associated viruses

• Conduct research on management of RPH for diverse alternatives:

Tests on - bio-pesticides, varietal resistance, judicious application of pesticides, cultural practices

• Survey on virus diseases of vegetables transmitted by vector insects for virus detection

• Collect information on present situation of pesticide use level & pesticide use pattern in crops & vegetables

• Training to target groups on management of rice planthoppers & viruses of vegetables

• Publication on management of RPH and viruses of rice & vegetables

References

ABPSD. 2013/2014. Statistical Information on Nepalese Agriculture. Ministry of Agriculture and Co-opratives, Agri-Business Promotion and Statistics Division (ABPSD), Singha Durbar, Kathmandy, Nepal.

KD. 2071. Krishi Diary (KD), Krishi Suchana tatha Sanchar Kendra, Harihar Bhawan, Lalitpur. Pp. 71-80.

Manandhar, D. N. 1999. Rice and Brown Planthopper: A Review. NARC/ CIMMIT, Nepal.

Pokhrel, S., P. N. Sharma, and F. P. Neupane. 1998-1999. Incidence and control of the rice plant-hoppers in Chitwan, Nepal. J. Inst. Agric. Anim. Sci. Vol. 19-20, p 55- 64.

Sharma, P. N., N. Mori, S. Takumi and C. Nakamura. 2014. Conventional and Molecular Studies of Brown Planthopper (Nilaparvata lugens Stal) Resistance Genes in Rice: A Basis for Future Study of Natural Insect Resistance Genes Using Molecular Markers in Nepal. Nepal Journal of Science and Technology Vol. 15, No. 1 (2014) 145-156.

Sharma, P.N., H.K. Manandhar, M.L. Vaidya, B.N. Mahto, G. Bhanandari, J. Mandal, and D.R. Kandel. 2013. Country Paper (Nepal). In: AFACI IPM Project Final Report, Collaboration Network for the Management of Migratory Rice Planthoppers and Associated Virus Diseases of Rice in Asia (11-1390802-000731-01). AFACI, RDA-Korea, Pp. 133-158.