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Research Priorities for Rice Pest Management in Tropical Asia: A Simulation Analysis of Yield Losses and Management Efficiencies

First author: UMR INRA-ENSAR BiO3P (Biologie des Organismes et des Populations appliquée à la Protection des Plantes), BP 35327, 35653 Le Rheu Cedex, France; second, third, fourth, and sixth authors: International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines; fifth author: School of Land and Food Sciences, The University of Queensland, Brisbane, Q 4072, Australia; seventh author: The Worldfish Center, DDG, Jalan Batu Maung, Batu Maung, 11960 Bayan Lepas, Penang, Malaysia; eighth and ninth authors: Narendra Deva University of Agriculture and Technology, Narendra Nagar, PO Kumarganj, 224 229 U.P., India; tenth author: China National Rice Research Institute, No. 359 Tiyuchang Road, Hangzhou 310006, Zhejiang, China; and eleventh author: Ecole Nationale Supérieure Agronomique de Rennes, 65 rue de Saint-Brieuc, CS 84215, 35042 Rennes cedex, France

A simulation study was conducted to assess the current and prospective efficiency of rice pest management and develop research priorities for lowland production situations in tropical Asia. Simulation modeling with the RICEPEST model provided the flexibility required to address varying production situations and diverse pest profiles (bacterial leaf blight, sheath blight, brown spot, leaf blast, neck blast, sheath rot, white heads, dead hearts, brown plant-hoppers, insect defoliators, and weeds). Operational definitions for management efficacy (injury reduction) and management efficiency (yield gain) were developed. This approach enabled the modeling of scenarios pertaining to different pest management strategies within the agroecological contexts of rice production and their associated pest injuries. Rice pests could be classified into two broad research priority-setting categories with respect to simulated yield losses and management efficiencies. One group, including weeds, sheath blight, and brown spot, consists of pests for which effective pest management tools need to be developed. The second group consists of leaf blast, neck blast, bacterial leaf blight, and brown plant-hoppers, for which the efficiency of current management methods is to be maintained. Simulated yield losses in future production situations indicated that a new type of rice plant with high-harvest index and high-biomass production (“New Plant Type”) was more vulnerable to pests than hybrid rice. Simulations also indicated that the impact of deployment of host resistance (e.g., through genetic engineering) was much larger when targeted against sheath blight than when targeted against stem borers. Simulated yield losses for combinations of production situations and injury profiles that dominate current lowland rice production in tropical Asia ranged from 140 to 230 g m^-2. For these combinations, the simulated efficiency of current pest management methods, expressed in terms of relative yield gains, ranged from 0.38 to 0.74. Overall, the analyses indicated that 120 to 200 × 10⁶ tons of grain yield are lost yearly to pests over the 87 × 10⁶ ha of lowland rice in tropical Asia. This also amounts to the potential gain that future pest management strategies could achieve, if deployed.

Additional keywords: Chilo suppressalis, Cnaphalocrocis medinalis, Cochliobolus miyabeanus, Cyperus spp., Echinochloa spp., Hydrellia philippina, Monochoria vaginalis, Nilaparvata lugens, Oryza sativa, Pyricularia oryzae, Rhizoctonia solani, Sarocladium oryzae, Scirpophaga incertulas, Scirpophaga innotata, Sesamia inferens, Xanthomonas campestris pv. oryzae.