White grubs, Scarabaeidae larvae (Insecta, Coleoptera) Control byplants in conservation agriculture:  effects on macrofaun...
Outline• Context & Objective  – Uplands rice production and constraints  – White grubs diversity and impacts  – Soil biofu...
Uplands rice production and              constraints• Rice, staple crop and food in Madagascar,• Grown on 1.3 million Ha, ...
Larva and adults of Madagascar’s             Scarabaeoidea (pests)         Heteroconus     Heteronychus      Heteronychus ...
White grubs damagesAttack at root or crown        Attack might be as severelevels according to species,   as heredeath of ...
Larva of Madagascar’s Scarabaeoidea            (Non-pests) Hexodon unicolor    Bricoptis    Euryiomia     unicolor        ...
Soil biofunctioning and macrofauna               functional groups       • Promote nutrient cycling,       • Participate o...
Major pathways for reducing the impact ofpests and diseases via plant species diversity      in agroecosystems (Ratnadass ...
Hypothesis and ObjectiveHypothesis: Increase in plant biodiversity + No- tillage + cover crops  macrofauna diversity  po...
Macrofauna’s food and nutrition • Predators        (other fauna) • Phytophagous     (plants) • Saprophagous     (decomposi...
Characteristics of the study     area   Antsirabe      Andranomanelatra (19°46’ 45’’S, 47°06’ 25’’ E) Central high plateau...
Experimental field layout in 2009-                   2010A1   A2   A3   A4    B1   B2    B3                               ...
Plants used as cover                                      crops for controlling                                          W...
Methods• Modified TSBF : 1 monolith of  25 cm x 25 cm x 30 cm per plot• Cut into litter and three layers:  0-10 cm, 10-20 ...
Methods (cont’d) • Hand sorting of invertebrates   > 2 mm • Identification (taxa), counting   and weighing of Macrofauna. ...
Mean abundance of Macrofauna          within cropping systems          Macrofauna functional group           density (Indi...
Abundance of detritiphagous    within cropping systems              Detritiphagous density                 (individuals m-...
Mean biomass of Macrofauna within        cropping systems        Macrofauna functional group biomass  25                  ...
Phytophagous biomass within cropping systems9                  Phytophagous biomass (g m-2)       a8              a76   a5...
Conclusion & Perspectives• Radish seems promising for phytophagous control.• In addition, it did not reduce macrofauna div...
Thank you            21
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White grubs, Scarabaeidae larvae (Insecta, Coleoptera) control by plants in CA: effects on macrofauna diversity. Bodovololona Rabary

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White grubs, Scarabaeidae larvae (Insecta, Coleoptera) control by plants in CA: effects on macrofauna diversity. Bodovololona Rabary

  1. 1. White grubs, Scarabaeidae larvae (Insecta, Coleoptera) Control byplants in conservation agriculture: effects on macrofauna diversity Bodovololona Rabary, Naudin K, Letourmy P, Mze Hassani I, Randriamanantsoa R, Michellon R, Rafarasoa L, Ratnadass A 1
  2. 2. Outline• Context & Objective – Uplands rice production and constraints – White grubs diversity and impacts – Soil biofunctioning and macrofauna functional groups – Hypothesis and Objective• Experimental setup – The study site and layouts – Sampling methods• Results and discussion• Conclusion 2
  3. 3. Uplands rice production and constraints• Rice, staple crop and food in Madagascar,• Grown on 1.3 million Ha, 29% are upland rice• Production of upland rice varieties is steadily increasing in Madagascar• Rice farmers are encountering several constraints of which: – High crop damage/loss caused by rice diseases and pests, including weeds. – Most pest damages are caused by white grubs 3
  4. 4. Larva and adults of Madagascar’s Scarabaeoidea (pests) Heteroconus Heteronychus Heteronychus Apicencya paradoxus bituberculatus arator rugifrons waterloti MELOLONTHIDAE DYNASTIDAE(Randriamanantsoa et al., 2010)
  5. 5. White grubs damagesAttack at root or crown Attack might be as severelevels according to species, as heredeath of plant The more efficient control method of white grubs is until 5 now ‘pesticides ‘
  6. 6. Larva of Madagascar’s Scarabaeoidea (Non-pests) Hexodon unicolor Bricoptis Euryiomia unicolor variolosa argentea Serica sp. DYNASTIDAE CETONIIDAE CETONIIDAE SERICIDAE (Randriamanantsoa et al., 2010)Some of them shows "soil engineering" behaviour 6
  7. 7. Soil biofunctioning and macrofauna functional groups • Promote nutrient cycling, • Participate on soil organic matter dynamics, C sequestration, emission of greenhouse gases control • Change the soil structure and water regime • Encourage the growth and the health of the plants.  build the quality and health of the soil over time  Increase the quantity and the efficiency of plant nutrients uptake(Lavelle et al., 1997; Frouz et al. 2001; Hättenschwiler& Gasser, 2005) 7
  8. 8. Major pathways for reducing the impact ofpests and diseases via plant species diversity in agroecosystems (Ratnadass et al., 2011) 8
  9. 9. Hypothesis and ObjectiveHypothesis: Increase in plant biodiversity + No- tillage + cover crops  macrofauna diversity  positive impact on pests.Research question: If the plants have positive impacts on pests, what are their effects on macrofauna biodiversity (Non-target species)? Approach based on functional groups diversity 9
  10. 10. Macrofauna’s food and nutrition • Predators (other fauna) • Phytophagous (plants) • Saprophagous (decomposing organic matter) • Detritiphagous (detritus) • Xylophagous (wood-eating) • Coprophagous (feces) • Geophagous (soil) Functional groups
  11. 11. Characteristics of the study area Antsirabe Andranomanelatra (19°46’ 45’’S, 47°06’ 25’’ E) Central high plateau with high- altitude tropical climate Altitude: 1600 m.a.s.l. Mean annual rainfall: 1450 mm Ferrallitic clayey soil (clay 61.90 %, pH: 5,7) More than 80 inhabitants / km² 11
  12. 12. Experimental field layout in 2009- 2010A1 A2 A3 A4 B1 B2 B3 NB4 F1 F8 F2 F7 F3 F6A8 A7 A6 A5 B8 B7 B6 B5 F4 F5D1 D2 D3 D4 E1 E2 E3 E4 C1 C2 C3 C4D8 D7 D6 D5 E8 E7 E6 E5 C8 C7 C6 C5 Sole Rice (NT) NT = Direct seeding Rice + Beans (NT) CT = Conventional Tillage Rice + Beans (CT)Legend Rice + Vetch (NT) Rice + Eleusine + Crotalaria (NT) Rice + Cleome + Cosmos + Tagetes (NT) Rice + Brachiaria (NT) 12 Rice + Radish (NT)
  13. 13. Plants used as cover crops for controlling White grubs Fodder Radish (Raphanus sativus) hairy vetch (Vicia villosa) Cosmos caudatusCleome hirta Tagetes minuta Brachiaria mulato Crotalaria grahamiana Eleusine coracana
  14. 14. Methods• Modified TSBF : 1 monolith of 25 cm x 25 cm x 30 cm per plot• Cut into litter and three layers: 0-10 cm, 10-20 cm, and 20-30 cm 14
  15. 15. Methods (cont’d) • Hand sorting of invertebrates > 2 mm • Identification (taxa), counting and weighing of Macrofauna. Conservation in alcohol 70 ° • ANOVA of transformed data for non-parametric tests. 15
  16. 16. Mean abundance of Macrofauna within cropping systems Macrofauna functional group density (Individuals m-2) Non-Identified1800 Saprophagous16001400 Geophagous12001000 Predators 800 Detritiphagous* 600 400 Phytophagous 200 0 16
  17. 17. Abundance of detritiphagous within cropping systems Detritiphagous density (individuals m-2)140 a120 a a a100 80 a 60 a ab 40 20 b 0 17
  18. 18. Mean biomass of Macrofauna within cropping systems Macrofauna functional group biomass 25 (g m-2) 20 Non-Identified 15 Saprophagous 10 Geophagous Predators 5 Detritiphagous 0 Phytophagous* 18
  19. 19. Phytophagous biomass within cropping systems9 Phytophagous biomass (g m-2) a8 a76 a5 a4 a a321 b ab0 19
  20. 20. Conclusion & Perspectives• Radish seems promising for phytophagous control.• In addition, it did not reduce macrofauna diversity and abundance.• Vetch was also favourable for macrofauna abundance but it did not express white grub pest control potential.• Our results emphasise the importance of studying a wide range of plants as cover crops or residue mulch for soil pest controlPerspectives• specific pest-suppressive effects of plants• explore more plant species.• Study the mechanisms involved 20
  21. 21. Thank you 21

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