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Agriculture and Natural Resources Agr. Nat. Resour. 55 (2021) 331–340 AGRICULTURE AND NATURAL RESOURCES Journal homepage: http://anres.kasetsart.org Research article Rice grassy stunt virus-free and pathogenic rice plants affect the brown planthopper (Nilaparvata lugens Stål) life cycle Thanat Na Phatthalunga, Wipa Tangkananonda,b,* a Department of Biotechnology, Faculty of Science and Technology, Thammasat University, Rangsit Campus, Klong Nueng, Klong Luang, Pathum Thani 12120, Thailand b Thammasat University Research Unit in Medicinal Chemistry, Thammasat University, Rangsit Campus, Klong Nueng, Klong Luang, Pathum Thani 12120, Thailand Article Info Abstract Article history: The developmental duration and performance of the brown planthopper (BPH, Received 14 September 2020 Nilaparvata lugens Stål), which is an important insect vector, can be influenced by Revised 1 March 2021 Accepted 26 April 2021 transmission of Rice grassy stunt virus (RGSV) in irrigated rice cultivation in Asian Available online 18 June 2021 countries including Thailand. In this study, the interaction effect between the statuses (non-viruliferous and viruliferous) of BPH populations on free leaves and RGSV-diseased Keywords: leaves were investigated using a 2 × 2 factorial in CRD with five replications. The results Brown planthopper (BPH, Nilaparvata lugens Stål), indicated that there were no significant (p > 0.05) interaction between the statuses of Plant-virus-vector interactions, BPH vectors and rice plants. In addition, the effects of different RGSV-inoculation Rice grassy stunt virus (RGSV), periods (10, 20, 30, 40, 50, 60, 70, 80 and 90 days after inoculation) on the developmental Rice plants, Survival rate periods of each life cycle stage of the non-viruliferous BPH population were investigated following CRD with five replications. The different inoculation periods of rice significantly affected (p < 0.05) developmental periods of the first and fourth instar nymph stages as well as on survival periods of both male and female short-winged brachypterous form and long-winged macropterous form. On the contrary RGSV-inoculation periods did not affect (p > 0.05) developmental periods of the eggs and other instar stages. These results can be used to improve the effectiveness of insect and rice viral disease control policies and strategies; epidemiological modelling of the virus and vector; outbreak prediction and protection; and agro-ecosystem management systems. Introduction the orders Hemiptera (true bugs: aphids, leafhoppers, and planthoppers), Homoptera (whiteflies) and Thysanoptera The majority of sap-sucking insects such as members of (thrips) are important viral transmitted-persistent manner vectors (Hogenhout et al., 2008). The brown planthopper (BPH), * Corresponding author. Nilaparvata lugens (Stål, 1854) (Hemiptera: Delphacidae), is E-mail address: [email protected] (W. Tangkananond) online 2452-316X print 2468-1458/Copyright © 2021. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/), production and hosting by Kasetsart University of Research and Development Institute on behalf of Kasetsart University. https://doi.org/10.34044/j.anres.2021.55.3.02 332 T. Na Phatthalung, W. Tangkananond / Agr. Nat. Resour. 55 (2021) 331–340 a monophagous sap-sucking insect pest of rice plants (Yang 2018) and planting season (Hu et al., 2019), while other aspects et al., 2017), and acts as the major vector of the Rice grassy have largely been ignored. stunt virus (RGSV or Rice rosette virus, Rice rosette Philippines Plant viral infections and the changes in the infected rice virus). RGSV was first reported in 1962 and identified in the plants can potentially influence the survival and developmental crops in 1964, which was the early “rice green revolution” periods of the insect vectors (Jiu et al., 2007; Chen et al., 2016). period, at the International Rice Research Institute, Los Baños, The current study was based on the hypothesis that behavior Laguna in the Philippines, but previously had been noticed of insect carrier and virus properties depend on rice plant in 1959–1960 at the Central Experiment Station, Bureau of integrity, such as food plant and host range. The effect of plant Plant Industry, Manila, the Philippines (Ling, 1972; Shikata virus on the vector reproductive potential is an important key et al., 1980). Later, it was reported in the other Asian rice- information to understand the ability and transmissibility of growing areas including Indonesia, Sri Lanka, India, Taiwan, infected rice plants. Therefore, the purposes of this study were Japan, Malaysia, China and Vietnam (Tantera et al., 1973; to assess the influence of RGSV on the performance of its BPH Anjaneyulu, 1974; Iwasaki and Shinkai, 1979; Chen, 1984; vector. This information will be used to develop the policies Chen and Chiu, 1989; Le et al., 2012). However, Hibino (1996) and strategies for plant protection and research strategy reported that the incidence of RGSV in Asia had declined since applications to help the country development. 1984 due to the changing proportion of the virus transmission ability of the BPH populations. Materials and Methods In Thailand, RGSV causes rice viral disease which is locally called ‘Rohk-kieow-dtia-kaao’. This disease was first noticed Viral materials in 1966 (Wattanakul and Weerapat, 1967). It was subsequently identified in the crops in December 1982 in local Thai rice The samples of RGSV-infected rice plants were kindly varieties, namely, ‘Kai-mook-dum’ and ‘Mo-ra-kot’, when rice provided and verified by the Division of Rice Research and crops were destroyed by RGSV and BPH outbreaks in Ban-Pho Development, Rice Department, Bangkok, Thailand, having district, Chachoengsao province along with scattered outbreaks been obtained from an irrigated rice field in Nong Suea district, in 20–30% of the experimental Thai rice fields in Lam-Luk- Pathum Thani province, Thailand, during 2018–2019. The Ka district, Pathum Thani province (Disthaporn et al., 1983). diseased rice plant samples were multiplied for routine stock In 1986, 1987 and 2007, there have been several scattered cultures in the greenhouse under conditions of 26±1°C, relative outbreaks in irrigated rice fields on the central plain and lower humidity of 70–90% and a photoperiod of 8 hr light to 16 hr north involving patterns of single and mixed infections with darkness; the stock plants were used as the viral plant sources Rice ragged stunt virus (RRSV: Oryzavirus, Reoviridae), and of inoculum to the BPH vectors. Rice tungro viruses (RTV) (Rice tungro spherical virus [RTSV: Waikavirus, Secoviridae] and Rice tungro baciliform virus Insect vector materials [RTBV: Tungrovirus, Caulimoviridae]) (Du et al., 2007). RGSV is a member of the genus Tenuivirus of the family The putative viruliferous and non-viruliferous BPH Phenuiviridae and is transmitted by the BPH vector in a populations (N. lugens Stål) were collected using light traps persistent propagative manner (Zheng et al., 2014). The specific in the same rice field containing the viral rice plant materials. typical phenotypes are induced by the RGSV infection and BPH Then they were maintained in insect rearing cages (40 cm × 40 behavior interactions and lead to the host plant physiological cm × 60 cm) and reared on rice plant seedlings (Oryza sativa and phenotypic changes such as excessive tillering (shoot L. variety RD-7; 7–10 cm in height and 6–9 d after germination branching), leaf yellowing (chlorosis), small leaf developing, [DAG]) for routine stock cultures under greenhouse conditions. sporadic yellow-brown colored spots on leaves and stunting To obtain the experimental BPH populations, the mature (Satoh et al., 2013). The life cycle of the BPH vector is females were generally transferred for oviposition. Then, after incomplete metamorphosis (hemi-metabolism) on host plants 48 hr, the RD-7 seedlings were replaced to ensure sufficient and a synchronous pattern, which is related to the biological nutrition and the infested rice plant seedlings with the BPH eggs and environmental conditions in the field (Dader et al., 2017). were cultured in insect-free cages for continuous production of Research to date has focused on the life cycle under different the stock culture of non-viruliferous BPH populations. Various conditions such as temperature (Manikandan et al., 2015; Guru stages of BPH offspring (third generation, F3) were used in the Pirasanna Pandi et al., 2018), host plant species (Horgan et al., study. T. Na Phatthalung, W. Tangkananond / Agr. Nat. Resour. 55 (2021) 331–340 333 Rice grassy stunt virus transmission and test sample preparation by using a 2 × 2 factorial in CRD with five replications. Simultaneously, the effects of different RGSV-inoculation After the molting of the third instar nymph, the non- periods or days after inoculation of rice plants (DAI: 10, 20, 30, viruliferous BPH populations were used for RGSV inoculation. 40, 50, 60, 70, 80 and 90) on the survival and developmental Fifty individual instar nymphs were fed on infected rice plant durations of each life cycle stage of the non-viruliferous samples for 24 hr of the acquisition feeding period (AFP) and BPH population were investigated following CRD with five the transmitted BPH populations were transferred and reared replications. The data were analyzed by using analysis of on the viral-free O. sativa L. var. RD-7 rice plant seedlings for variance facilitated by the IBM SPSS 16.0 software package 3 d of the latent period (LP).
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