Alain Ratnadass

Protection of Upland Rice at Lake Alaotra (Madagascar) from Black Beetle Damage (Heteronychus plebejus) (Coleoptera: Dynastidae) by Seed Dressing

In Madagascar, growing demand for rice and resulting increased pressure on inundated lands has favoured the cultivation of upland rain-fed rice on hill slopes. Due to the instability of the ecosystem, this type of agriculture cannot meet the objectives of both sustainability and high yields if conventional tillage is used, particularly due to high erosion risk. Direct seeding, mulch-based cropping (DMC) systems have opened new prospects for upland rice.

Research and Development Priorities in the Face of Climate Change and Rapidly Evolving Pests

Agriculture faces the challenge of meeting increasing food demands whilst simultaneously satisfying ever stringent sustainability goals. Taken together with the ever increasing rate of integrated globalisation and other anthropogenic impacts, this challenge is further complicated by climate change. Climate change is indeed increasingly recognised as a considerable risk to agriculture in the European Union, particularly with respect to direct impacts on crop production and yield stability. A major impact threat is the further risk from new and emerging invasive alien species, and potential novel pathogenically aggressive adaptations in existing indigenous pests and pathogens, which, hitherto, have been managed with conventional practices and approaches.

Ecological interactions within the biodiversity of cultivated systems

Various types of biodiversities can be found within the cultivated plot and in its surrounding environment: plant, animal and microbial biodiversities; aboveground and belowground biodiversities; productive, resource, destructive biodiversities, etc.

Effect of Cover Crop Residues on White Grubs and Adults of Heteronychus bituberculatus (Coleoptera: Dynastidae) and on the Damage They Cause to Upland Rice

Black beetles (Heteronychus spp., Coleoptera: Dynastidae) are significant pests of upland rice in the Central Highlands of Madagascar, particularly in some conservation agriculture (CA) systems. On the other hand, certain species of cover crops used in CA systems may have a suppressive effect on black beetle populations or reduce the damage they cause to rice plants. Between 2009 and 2011, we conducted a laboratory study on the possible effects of adding dried ground plant parts (hereafter ‘residues’) to the soil on larvae (white grubs) and adults (black beetles) of Heteronychus bituberculatus. Ten cover crop species were tested: Cajanus cajan, Crotalaria grahamiana, Desmodium intortum and Vicia villosa (Fabaceae); Brachiaria ruziziensis and Eleusine coracana (Poaceae); Cosmos caudatus and Tagetes minuta (Asteraceae); Cleome hirta (Capparaceae); and Raphanus sativus (Brassicaceae). Adding residues of C. grahamiana, E. coracana and C. caudatus resulted in significantly higher larval mortality than in the control treatments, while residues of R. sativus had a marginally significant effect. Adding residues of C. grahamiana, C. caudatus, C. hirta, T. minuta and R. sativus significantly reduced damage caused by adult black beetles.