Community composition of invasive, outbreak, and non-pest snail species along a source spring-to-fishpond gradient in a spatially structured aquacultural region

Biodiversity is good for you Changes in biodiversity have the potential to either increase or reduce the incidence of infectious disease in plants and animals — including humans — because they involve interactions among species. At a minimum, this requires a host and a pathogen; often many more species are involved, including additional hosts, vectors and other organisms with which these species interact. Felicia Keesing and colleagues review the evidence that reduced biodiversity affects the transmission of infectious diseases of humans, other animals and plants. Despite important questions still to be answered, they conclude that the evidence that biodiversity exerts a protective effect on infectious diseases is sufficiently strong to include biodiversity protection as a strategy to improve health. Supplementary information The online version of this article (doi:10.1038/nature09575) contains supplementary material, which is available to authorized users.

Like all species, humans have exercised their impulse to perpetuate and propagate themselves. In doing so, we have domesticated landscapes and ecosystems in ways that enhance our food supplies, reduce exposure to predators and natural dangers, and promote commerce. On average, the net benefits to humankind of domesticated nature have been positive. We have, of course, made mistakes, causing unforeseen changes in ecosystem attributes, while leaving few, if any, truly wild places on Earth. Going into the future, scientists can help humanity to domesticate nature more wisely by quantifying the tradeoffs among ecosystem services, such as how increasing the provision of one service may decrease ecosystem resilience and the provision of other services.

The cross-edge spillover of subsidized predators from anthropogenic to natural habitats is an important process affecting wildlife, especially bird, populations in fragmented landscapes. However, the importance of the spillover of insect natural enemies from agricultural to natural habitats is unknown, despite the abundance of studies examining movement in the opposite direction. Here, we synthesize studies from various ecological sub-disciplines to suggest that spillover of agriculturally subsidized insect natural enemies may be an important process affecting prey populations in natural habitat fragments. This contention is based on (1) the ubiquity of agricultural-natural edges in human dominated landscapes; (2) the substantial literature illustrating that crop and natural habitats share important insect predators; and (3) the clear importance of the landscape matrix, specifically distance to ecological edges, in influencing predator impacts in agroecosystems. Further support emerges from theory on the importance of cross-boundary subsidies for within site consumer-resource dynamics. In particular, high productivity and temporally variable resource abundance in agricultural systems are predicted to result in strong spillover effects. More empirical work examining the prevalence and significance of such natural enemy spillover will be critical to a broader understanding of fragmentation impacts on insect predator-prey interactions.