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Oecologia (2010) 163:949960 DOI 10.1007/s00442-010-1633-1
PLANT-ANIMAL INTERACTIONS - ORIGINAL PAPER
EVects of sap-feeding insect herbivores on growth and reproduction of woody plants: a meta-analysis of experimental studies
Elena L. Zvereva Vojt5ch Lanta Mikhail V. Kozlov
Received: 20 December 2009 / Accepted: 30 March 2010 / Published online: 16 April 2010 Springer-Verlag 2010
Abstract The majority of generalisations concerning plant responses to herbivory are based on studies of natural or simulated defoliation. However, eVects caused by insects feeding on plant sap are likely to diVer from the eVects of folivory. We assessed the general patterns and sources of variation in the eVects of sap feeding on growth, photo-synthesis, and reproduction of woody plants through a meta-analysis of 272 eVect sizes calculated from 52 papers. Sap-feeders signiWcantly reduced growth (29%), repro
duction (17%), and photosynthesis (27%); seedlings
suVered more than saplings and mature trees. Deciduous and evergreen woody plants did not diVer in their abilities to tolerate damage imposed by sap-feeders. DiVerent plant parts, in particular below- and above-ground organs, responded similarly to damage, indicating that sap-feeders did not change the resource allocation in plants. The strongest eVects were caused by mesophyll and phloem feeders, and the weakest by xylem feeders. Generalist sap-feeders reduced plant performance to a greater extent than did specialists. Methodology substantially inXuenced the outcomes of the primary studies; experiments conducted in greenhouses yielded stronger negative eVects than Weld experiments; shorter (<12 months) experiments showed bigger growth reduction in response to sap feeding than longer experiments; natural levels of herbivory caused
weaker eVects than infestation of experimental plants by sap-feeders. Studies conducted at higher temperatures yielded stronger detrimental eVects of sap-feeders on their hosts. We conclude that sap-feeders impose a more severe overall negative impact on plant performance than do defoliators, mostly due to the lower abilities of woody plants to compensate for sap-feeders damage in terms of both growth and photosynthesis.
Keywords Compensatory responses Photosynthesis Plant growth Reproduction Resource allocation
Introduction
Herbivores, by consuming a large proportion of primary production, contribute to the regulation of plant communities in many environments (Crawley 1989; Marquis 2004). However, while outbreaks of defoliators attracted the attention of ecologists decades ago (Barbosa and Schultz 1987), sap-feeding insects have been overlooked in many ecosystem-level studies (Hodkinson and Hughes 1982;...