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United States Department of Agriculture

Agricultural Research Service

Research Project: PROACTIVE MANAGEMENT FOR SUSTAINABLE RANGELAND PRODUCTION Title: Variation in specificity of soil-borne pathogens from a plant’s native range versus its non-native range

Authors
item Reinhart, Kurt
item Van Der Putten, W - NETHERLANDS INST OF ECOLO
item Tytgat, T - NETHERLANDS INST OF ECOLO
item Clay, Keith - INDIANA UNIV, BLOOMINGTON

Submitted to: International Journal of Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2011
Publication Date: April 1, 2011
Citation: Reinhart, K.O., Van Der Putten, W.H., Tytgat, T., Clay, K. 2011. Variation in specificity of soil-borne pathogens from a plant’s native range versus its non-native range. International Journal of Ecology. online doi:10.1155/2011/737298

Interpretive Summary: • Contrary to predictions, soil-borne pathogens associated with an invading tree in Europe are more host-specific than those associated with the tree in its native range. • This biogeographical variation in degree of host-specialization by groups of related pathogens contradicts a major assumption of Invasion Ecology—successful invaders have left their virulent specialist enemies behind. • Theoretical implications- Nascent pathosystems associated with invaders may provide evolutionary biologists with unique opportunities to explore changes in host-frequency, host-specialization, and pathogen virulence over time. • Management implications- Incorporating resident enemies into an integrated pest management plan for invasive plants may be a promising form of biocontrol that could reduce the associated costs, improve success of establishment by utilizing enemies preadapted to the environment, avoid the associated constraints of conducting efficacy trials with restrictive quarantines, and reduce environmental risks of importing “exotic” pests to control the invader.

Technical Abstract: Invasive species are often assumed to have escaped from specialist enemies. A few studies support this but only in the context of species-level specificity, and not ecotype-specificity, of mostly insect herbivores/parasites. Here we compare the ecotype-specificity of soil-borne pathogens (Pythium spp.) associated with an invasive tree (Prunus serotina) in its native vs. Non-native ranges. Host ecotype had little effect on measures of pathogenic activity when interacting with Pythium from the native range. In contrast, pathogenic responses varied between host ecotypes when interacting with Pythium from the non-native range suggesting a greater level of host-specificity by the pathogens from the non-native than native ranges. Encountering more specialized enemies in the non-native than native ranges is counter to general invasion ecology predictions; however, functionally these Pythium isolates are less virulent than those in the native range. Further empirical evidence is necessary to interpret the importance of different types of enemy host-specificity and virulence to determine if enemy virulence is linked to levels of host-specificity. This is necessary to evaluate the efficacy of organisms as potential biological control agents of foreign (classical biological control) and endemic origin and improve our basic understanding of invasion biology and the evolution of host-pathogen interactions.

Last Modified: 11/21/2014