by
Jiaan Cheng, Professor, Institute of Insect Sciences, Zhejiang University, Hangzhou, China
The National Natural Science Foundation of China’s has approved a proposal prepared jointly by the Institute of Insect Sciences, Zhejiang University (ZU) and IRRI to undertake “Comparative Analysis of Ecological Functions Regulating Planthopper Outbreaks in Tropical and Chinese Rice Ecosystems”. The approved project of 1 million yuan (~ US$ 147,000) for 3 years starting in January 2010 will provide counterpart funding to the Rice Planthopper Project that will enable scientists from ZU to work at IRRI as well as IRRI scientists to work in China. The primary objective of the NSFC project is to understand the main components, related mechanisms and their interactions in planthopper regulation in rice ecosystems of tropical and temperate environments. The findings of this collaboration will contribute towards the Rice Planthopper Project’s output to develop ecological engineering methods to restore arthropod biodiversity, ecosystem services and resilience to protect rice crops from planthopper invasions leading to outbreaks.
Rice planthoppers continue to be the biggest threat to China’s rice production and other intensive area. Annually China loses about 2 million tons of rice due to planthopper outbreaks. In years when summer temperatures are elevated, like in 2005, as much as 2.8 millions of rice can be lost in just a few months. In the last 4 consecutive years, 2005-2008, China has experienced the worst ever attacks by the rice planthoopers. In the immediate future, this problem seems likely to intensify, especially since the planthopper have developed resistance to several insecticides. The biodiversity of parasites and predators in most rice fields are reduced and farmers’ insecticide use is increasing causing human health problems and pollution of waterways. The planthopper threat needs to be addressed by developing more sustainable ways to manage them. Recently large areas of rice in the seedling stages in Yunnan province were destroyed by immigrating adults, probably from Vietnam. In the last 4 years, planthopper populations recorded in Zhejiang province have been way above threshold for outbreak level (see figure).
Annual mean peak densities of rice planthoppers sampled in unsprayed fields in Jiaxing, Zhejiang province
The ZU-IRRI project will investigate the impact of cropping patterns and non crop habitats on initial populations of planthoppers and natural enemy diversity, the interactions between rice and planthoppers in a multi-trophic systems and relevant mechanisms, impact of agrochemicals on interactions between planthoppers and natural enemies, comparative analysis of predation to planthoppers between tropical and Chinese rice ecosystems; and develop approaches for rice ecosystem design to reduce risk of planthopper outbreaks by strengthening the ecological regulatory functions.
