by
J.L.A. Catindig, S.C. Villareal and K.L. Heong
International Rice Research Institute
Los Baños, Philippines
http://www.cbd.int/2010/welcome/
Biodiversity loss in the world has been significant and it is unlikely that the targets adopted in the 2002 World Summit for Sustainable Development in Johannesburg will be met. The loss in pollinator biodiversity was found to have significantly lowered pollination services in Europe. Similar trends are probably occurring in Asia but there are limited studies to assess biodiversity and ecosystem services. Farmers rely on the diversity of natural enemies in rice production systems to provide them with the essential services to protect their crops from invading pests. Yet this rich diversity is constantly threatened and biodiversity loss is accelerating because of knowledge gaps and human activities. In rice production this trend can be reversed without compromising productivity if practices are modified and adjusted and farmers are motivated to conserve arthropod biodiversity.
The ADB-IRRI Rice Planthopper Project will make contributions towards the 2010 IYB as one theme is to assess and develop ways to enhance predator and parasitoid biodiversity and their services through rationalizing insecticide use and ecological engineering approaches. The Project has also conducted sociological studies to understand farmers’ knowledge, attitudes and practices towards maintaining flowering plants along the bunds. Farmers often view these plants as weeds and hosts for pests and tend to apply herbicides on the bunds. Such beliefs and practices will need to be changed by communicating the positive values of the beneficial flowers and adjusting policies to motivate these practices.
Researchers in China, Thailand, and Vietnam are experimenting with the introduction of nectar rich flower plants onto the bunds and non rice areas as resources for predators and parasitoids. Among the plants being used are Sesame indicum (sesame), Ageratum conyzoides (billy goat weed) Crassocephalum crepidioides (redflower ragleaf), Emilia sonchifolia (cupid’s shaving-bush), Tridax procumbens (wild daisy), and Vernonia cinerea (ironweed). Some of the plants belonging to the family Compositae in particular have been found attracting numerous hymenopterans and syrphids in China.
Bee visiting flower (Indian aster, Kalimeris indica) common on rice bunds in China
Two common species of compositae in rice ecosystems, A: Tridax procumbens and B: Vernonia cinerea.
In the Philippines, we found Vernonia cinerea attracting coccinellids such as Micraspis sp.
Lady bird, Micraspis sp. on Vernonia cinerea. Flower
To enhance arthropod biodiversity in and around rice fields require minimizing the disruptive factors such as early season insecticide sprays and maximizing the biodiversity of predators and parasitoids through restoring floral biodiversity. Thus the ecological engineering approaches to be adopted are both the withholding of early season insecticide sprays and populating bunds and non rice habitats with beneficial plants.
