Global food security requires increased crop productivity to meet escalating demand(1-3). Current food production systems are heavily dependent on synthetic inputs that threaten the environment and human well-being(2,4,5). Biodiversity, for instance, is key to the provision of ecosystem services such as pest control(6,7), but is eroded in conventional agricultural systems. Yet the conservation and reinstatement of biodiversity is challenging(5,8,9), and it remains unclear whether the promotion of biodiversity can reduce reliance on inputs without penalizing yields on a regional scale. Here we present results from multi-site field studies replicated in Thailand, China and Vietnam over a period of four years, in which we grew nectar-producing plants around rice fields, and monitored levels of pest infestation, insecticide use and yields. Compiling the data from all sites, we report that this inexpensive intervention significantly reduced populations of two key pests, reduced insecticide applications by 70%, increased grain yields by 5% and delivered an economic advantage of 7.5%. Additional field studies showed that predators and parasitoids of the main rice pests, together with detritivores, were more abundant in the presence of nectar-producing plants. We conclude that a simple diversification approach, in this case the growth of nectar-producing plants, can contribute to the ecological intensification of agricultural systems.

The brown planthopper (BPH) Nilaparvata lugens, whitebacked planthopper (WBPH) Sogatella furcifera and smaller BPH Laodelphax striatellus increasingly exhibit resistance to insecticides and adaptation to resistant varieties, so they threaten food security. This review draws together, for the first time, information on the parasitoids of planthopper pests of rice from the non-English literature published in Asia. This is integrated with the English language literature to provide a comprehensive analysis. Planthopper pests of rice are attacked by a large range of parasitoids from Strepsiptera, Diptera and, especially, Hymenoptera. Levels of field parasitism vary widely between parasitoid species and locations. For many taxa, especially within Mymaridae, there is evidence that non-crop habitats are important as overwintering habitat in which alternative hosts are available. These source habitats may promote early season parasitism of pest Hemiptera in rice crops, and their movement into crops could be manipulated with applications of herbivoreinduced plant volatiles. Non-crop plants can also provide nectar to improve parasitoid longevity and fecundity. Despite evidence for the importance of environmental factors affecting parasitoids of rice pests, the use of habitat manipulation to enhance biological control in the world's most important crop is surprisingly underrepresented in the literature. Current research in China, Vietnam and Thailand on ecological engineering, carefully selected vegetation diversity introduced without disrupting profitable farming, is briefly reported. Although the most important pest, BPH (N. lugens), is a migratory species, maintaining local communities of parasitoids and other natural enemies offers scope to prevent even r-selected pests from reaching damaging population densities.

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