PT  - JOURNAL ARTICLE
AU  - Y. Xing
AU  - J. F. Hernandez Nopsa
AU  - J. Andrade-Piedra
AU  - F. Beed
AU  - G. Blomme
AU  - M. Carvajal Yepes
AU  - D. L. Coyne
AU  - G. A. Forbes
AU  - J. Kreuze
AU  - J. Kroschel
AU  - P. L. Kumar
AU  - J. P. Legg
AU  - M. Parker
AU  - E. Schulte-Geldermann
AU  - K. A. Garrett
TI  - Global cropland connectivity: A risk factor for invasion and saturation by emerging pathogens and pests
AID  - 10.1101/106542
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 106542
4099  - http://biorxiv.org/content/early/2017/02/10/106542.short
4100  - http://biorxiv.org/content/early/2017/02/10/106542.full
AB  - The geographic pattern of croplands is an important risk factor for the invasion of crop-specific pathogens and arthropods, and saturation by endemic pests. Understanding the structure of cropland networks supports sampling and mitigation strategies. We evaluated global networks of key vegetatively-propagated crops (banana, cassava, potato, sweetpotato, and yam) of particular importance to food security in the tropics. The risk of damage from diseases transmitted through vegetative propagation is a particular concern. We analyzed the structure of cropland networks for each crop, where the existence of a link between geographic location pairs was determined using a gravity model, as a function of the distance between the pair of locations and the product of the harvested crop area in the two locations. Networks were evaluated using a novel index of pathogen or arthropod invasion and saturation risk, based on the role of locations in bridging cropland areas and the degree of connectedness of a location and its neighbors. For example, in addition to locations with high risk due to high cropping density, locations with high risk because of their role as bridges for cassava include South-Central Nigeria, Central Ghana, and Southwestern Democratic Republic of Congo. For potato, bridges include Central and Southern Poland and Northern Ukraine. The highly-linked hub and bridge locations we identified are likely priorities for surveillance and management, and for tracing intra-region movement of pathogens and pests. Integrated analyses of invasion and saturation risk can simultaneously evaluate risk due to cropland connectivity along with other risk factors such as climate and trade routes.