Losing a battle but winning the war moving past p

Authors: Leone M Brown Greg A Breed Paul M Severns Elizabeth E Crone

Publish Date: 2016/12/02

Volume: 183, Issue: 2, Pages: 441-453

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Abstract

Introduced plants can positively affect population viability by augmenting the diet of native herbivores but can negatively affect populations if they are subpar or toxic resources In organisms with complex life histories such as insects specializing on host plants the impacts of a novel host may differ across life stages with divergent effects on population persistence Most research on effects of novel hosts has focused on adult oviposition preference and larval performance but adult preference may not optimize offspring performance nor be indicative of host quality from a demographic perspective We compared population growth rates of the Baltimore checkerspot butterfly Euphydryas phaeton on an introduced host Plantago lanceolata English plantain and the native host Chelone glabra white turtlehead Contrary to the previous findings suggesting that P lanceolata could be a population sink we found higher population growth rates λ on the introduced than the native host even though some component parameters of λ were higher on the native host Our findings illustrate the importance of moving beyond preference–performance studies to integrate vital rates across all life stages for evaluating herbivore–host plant relationships Single measures of preference or performance are not sufficient proxies for overall host quality nor do they provide insights into longer term consequences of novel host plant use In our system in particular P lanceolata may buffer checkerspot populations when the native host is limiting but high growth rates could lead to crashes over longer time scalesWe thank the Conservation Commission of the town of Harvard MA for allowing us to use their land for our research We also thank Aubrie James Emma Sass Natasha Tigreros Norah Warchola Ailene Ettinger Lauren Redosh Haley Coffman Livia BaerBositis Deane Bowers Natalie Kerr Dash Donnelly Cheryl Schultz Glenda Wardle Michal Bodziewicz and Rafal Zwolak for help with fieldwork We are grateful to Richard Chandler for helpful advice regarding population models and we are indebted to the Handling Editor and three anonymous reviewers for incredibly helpful comments and suggestions that greatly improved this manuscript This work was supported by a National Science Foundation Award to LMB DEB1402287 and a Department of Defense SERDP Award to EEC RC2119 with additional support from Harvard Forest Harvard University and Tufts UniversityEEC GAB and PMS conceived the original ideas and designed and carried out fieldwork conducted in 2012 LMB and EEC designed and carried out fieldwork conducted in 2013 and 2014 LMB and EEC collated and analyzed all of the data and wrote the manuscript

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