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

A presentation at the WCCA 2011 event in Brisbane.

1. Bodovololona Rabary, Naudin K, Letourmy P, Mze Hassani I, Randriamanantsoa R, Michellon R, Rafarasoa L, Ratnadass A White grubs, Scarabaeidae larvae ( Insecta , Coleoptera ) Control by plants in conservation agriculture : effects on macrofauna diversity 1

2. 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 Outline 2

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. Larva and adults of Madagascar’s Scarabaeoidea ( pests ) Heteroconus paradoxus Heteronychus bituberculatus Heteronychus arator rugifrons Apicencya waterloti MELOLONTHIDAE DYNASTIDAE ( Randriamanantsoa et al., 2010)

5. White grubs damages 5 Attack at root or crown levels according to species, death of plant Attack might be as severe as here The more efficient control method of white grubs is until now ‘pesticides ‘

6. Larva of Madagascar’s Scarabaeoidea (Non- pests ) 6 Hexodon unicolor unicolor Bricoptis variolosa Serica sp . Euryiomia argentea SERICIDAE DYNASTIDAE CETONIIDAE CETONIIDAE ( Randriamanantsoa et al., 2010) Some of them shows "soil engineering" behaviour

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 7 (Lavelle et al., 1997; Frouz et al. 2001; Hättenschwiler & Gasser, 2005)

8. Major pathways for reducing the impact of pests and diseases via plant species diversity in agroecosystems ( Ratnadass et al., 2011) 8

9. Hypothesis and Objective Hypothesis : 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. 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. Characteristics of the study area Antsirabe Andranomanelatra Altitude : 1600 m.a.s.l. Mean annual r ainfall : 1450 mm   Central high plateau with high-altitude tropical climate  Ferrallitic clayey soil (clay 61.90 % , pH: 5,7 ) (19°46’ 45’’S, 47°06’ 25’’ E)   More than 80 inhabitants / km²   11

12. N Sole Rice (NT) Rice + Beans (NT) Rice + Beans (CT) Rice + Vetch (NT) Rice + Eleusine + Crotalaria (NT) Rice + Cleome + Cosmos + Tagetes (NT) Rice + Brachiaria (NT) Rice + Radish (NT) Legend 12 Experimental field layout in 2009-2010 NT = Direct seeding CT = Conventional Tillage

13. hairy vetch ( Vicia villosa ) Brachiaria mulato Crotalaria grahamiana Cleome hirta Tagetes minuta Cosmos caudatus Fodder Radish ( Raphanus sativus ) Plants used as cover crops for controlling White grubs Eleusine coracana

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. 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

17. 17 Abundance of detritiphagous within cropping systems

18. 18 Mean biomass of Macrofauna within cropping systems

19. 19 Phytophagous biomass within cropping systems

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 control Perspectives specific pest-suppressive effects of plants explore more plant species. Study the mechanisms involved 20

21. 21 Thank you