Pest Management in Tropical Cereals: Rice & Maize. Defoliators: migratory. More Defoliators. Maize. BCCM 2012: IPM case studies. Sorghum Millet Tef

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1 Source: BCCM 2012: IPM case studies Pest Management in Tropical Cereals: Rice & Maize also Sorghum Millet Tef RPB 2011; tropical_cereals v. 2.4 Defoliators: migratory Locusts (Locusta, Schistocerca etc.) Armyworms (e.g. Spodoptera exempta) More Defoliators Other Orthoptera: e.g. Ruspolia spp. (Homorocoryphus nitidulus) Harvester termites (Hodotermes spp.) Leafcutter ants etc Maize Centre of diversity is Mexico: thousands of varieties are still sown. Archaeological studies indicate that maize was domesticated in Oaxaca 10,000 years ago Introduction to Europe from the American continent via Christopher Columbus. Today, it is grown worldwide: staple in Africa and parts of China Varietal development: favorable characteristics include nutritional value, tolerance to acidic or salty soils, resistance to diseases (mostly viruses) and insects (Bt), 1 genetic line fixes nitrogen Mexico is the seat of the International Centre for Investigations for the Improvement of Maize and Wheat (CIMMYT): part of the CGIAR system (that includes IRRI). Top maize producers, 2010 Country Production ($'000) Production (MT) USA 26,714, ,165,000 China 10,189, ,540,788 Brazil 2,966,606 56,060,400 Argentina 2,768,066 22,676,900 Indonesia 1,798,352 18,364,400 Mexico 1,432,809 23,301,900 India 1,281,566 14,060,000 South Africa 1,279,637 12,815,000 France 881,864 13,975,000 Nigeria 816,133 7,305,530 East & Central Africa 2,423,681 18,692,900 (Ethiopia, Tanzania, Malawi, Kenya, Zambia) 1

2 Photos: GAM, Some key problems: N. America & Europe European corn borer (Ostrinia nubilalis) Originally Proso millet (Panicum miliaceum) in E Europe/ Middle East Invasive to N. America (since 1917) Diabrotica spp. incl. Western corn rootworm, D. virgifera Helicoverpa zea Problems: world Leaf feeders Sucking pests - virus disease transmission Stemborers Earworms Storage pests Fungus diseases (minor for maize) Weeds - including parasitic witchweeds Striga spp. Weed management: Pre-emergence herbicide application Virus disease transmission Tolerant / resistant varieties / hybrids now available Plant early in the season Eradicate grass weeds Control vectors Maize streak virus (MSV) transmitted by Cicadulina mbila Helicoverpa spp. Corn earworm: H. armigera - polyphagous (Africa, Asia) H. zea (Americas) Maize stemborers Include: Chilo partellus Busseola fusca (maize stalk borer) Controls: Cultural (remove crop residues) Plant resistance (moderate tolerance) Biological (little success) Chemical - to kill young larvae before they enter the stems 2

3 Vu Nguyen, VN Source: Granule application Storage pests Include: Sitophilus, Protsephanus, Sitatroga etc and rodents Rice Rice (genus Oryza) can be tolerant to desert, hot, humid, flooded, dry and cool conditions, and grows in saline, alkaline and acidic soils. Of 23 Oryza species, 2 have been cultivated: Oryza sativa, originated in the humid tropics of Asia: cultivated rice has evolved into three eco-geographic races - indica, japonica and javanica. O. glaberrima is from West Africa Top 12 rice producers, 2010 (paddy production) Country Production (Int $'000) Production (MT) China 48,765, ,212,010 India 32,167, ,620,000 Indonesia 17,934,975 66,411,500 Bangladesh 13,588,854 49,355,000 Viet Nam 10,697,573 39,988,900 Myanmar 8,142,863 33,204,500 Thailand 7,913,219 31,597,200 Philippines 4,159,474 15,771,700 Brazil 3,089,811 11,308,900 USA 3,019,696 11,027,000 Japan 2,940,698 10,600,000 Cambodia 2,206,227 8,245,320 Rice Planting Paddy rice Transplanted Direct seeded Deep- water... Greatest area rain fed Water control (irrigation): often enables 2-3 crops per year Also very long-stemmed "floating rice in deep water 3

4 Preparation and planting ICM of tropical rice Issues include: Cultivation practices (upland, transplanted, direct seeded etc.) Selection of rice varieties True crop losses Role of natural enemies Role of pesticides Application issues Rice farmers don t only apply insecticides! Mode of pest attack Application equipment Formulations (for spraying, GRs etc.) Safety Crop architecture & biological targets Top e.g. rice bug, hispa Whole canopy e.g. eggs of stemborers, rice blast fungicides Base e.g. brown plant hopper, sheath blight Root zone (systemic pesticides) Anamorphic rice diseases Bacterial blight ( Kresek ) Rice blast Magnaporthe grisea = Pyricularia oryzae Sheath blight Rhizoctonia solanii Wilting appears sporadically in the field and may cause serious damage. Due to early systemic infection of from infected seeds and bacterium spread by contact with geminating seedlings. Commonly occurs within 3-4 weeks after planting resulting in either the death of whole the plants of wilting of only a few leaves. 4

5 Take a break Shoot & stem feeders Whorl maggot (Hydrellia spp.) Gall Midge (Orseolia spp.) Stemborers Lepidoptera Diptera: Diopsidae (Africa) S.E. Asian stemborers Yellow stemborer Scirpophaga incertulas Lepidoptera: Pyralidae include: Yellow stemborer Scirpophaga incertulas Striped stemborer Chilo suppressalis Lepidoptera: Noctuidae Pink stemborer Sesamia inferens Stemborer symptoms "Dead hearts" Management Short-duration varieties (high yielding) Insecticides "White heads" 5

6 Courtesy IRRI Sucking insects Leafhoppers (Nephotettix spp.) (virus disease vectors) Planthoppers brown planthopper (BPH) Nilaparvata lugens white-backed planthopper Sogatella furcifera Heteroptera: rice bug (Leptocorisa spp.) other panicle pests black bug (Scotinophara spp.) Brown planthopper (BPH) Nilaparvata lugens hopper burn Sampling Natural enemies Parasitoids (e.g. Dryinidae) Cyrtorhinus lividipennis Resistant varieties and Biotypes also a vector of virus diseases Grassy stunt Response (hopperburn) of susceptible rice varieties with no resistance gene (IR 8 to IR24) and varieties with Bph1 (IR 26 to IR 30), bph2 (IR 32 to IR 42), Bph3 (IR 13543)... now bph4 (IR 13240) genes for resistance. Ragged stunt 6

7 Photos: IRRI Green leafhoppers (Nephotettix spp.) (virus disease vectors: e.g. Tungro ) Pesticides on rice: issues Human toxicity Economic necessity? Resurgence (especially of hoppers) impact on natural enemies crop-insect physiological responses Pesticides: especially neurotoxic insecticides Loevinsohn, 1987 documented and undocumented! Insecticide-induced resurgence BPH changed from the status of secondary pest to a major yield constraint beginning in the l960s. Increased use of resurgence-inducing insecticides (including OPs and pyrethroids) has been considered the major cause of intensified brown planthopper problems. Resurgence-inducing insecticides are selectively toxic to the predators of the brown planthopper and result in a dramatic population increase of the brown planthopper after insecticide application. See: Rice is an agro-ecosystem Pesticides such as pyrethroids are toxic to NTOs such as fish - despite claims to the contrary! Approaches Green revolution Monitoring - response (action thresholds) Low input IPM (FAO initiative): via Farmer Field Schools (FFS) emphasising conservation of natural enemies BUT thresholds are dramatically lower in presence of virus diseases 7

8 Heteroptera: Rice Bugs (especially Leptocorisa spp.) & rice black bugs (Scotinophara spp.) (Can also cause hopper burn) Leaf feeders Leaf-folder (Cnaphalocrocis spp.) Case-worm (Nymphula depunctalis) Hispa (Dicladispa armigera) Army worms & cutworms Mythimna, Spodoptera spp Other defoliators: e.g. Oxya spp. (Acrididae) Case-worm (Nymphula depunctalis) Leaf-folder (Cnaphalocrocis medinalis) True economic damage? Hispa (Dicladispa armigera) Cutworms (Spodoptera litura) & Armyworms ( Mythimna separata) a.k.a. ear-head cutting caterpillar 8

9 Photo: IRRI Upland rice Vertebrates & Molluscs Rodents several spp. including: Rattus argentiventer Bandicota bengalensis Birds: including Munias (Lonchura spp.) Gastropoda Golden apple snail (Asia & Americas) (Pomacea canaliculata) Lanistes ovum (Africa) Rodents: Rattus spp. incl. R. argentiventer Bandicota bengalensis Conclusions Tropical cereals: strong political and other pressures to minimise inputs for small-holder farmers IPM is also about control of diseases (including viruses) and weeds Emphasis on improved varieties and cultural methods (timing, water management for rice) Insecticides used often still tend to be the cheap, older, neurotoxic compounds and may cause resurgence of BPH etc. Nevertheless, pesticides are still widely used 9