Effect of simulated herbivory on growth of the invasive weed Hygrophila polysperma: Experimental and predictive approaches Abhishek Mukherjee a,⇑ , James W. Jones b , James P. Cuda a , Gregory Kiker b , William A. Overholt c a Entomology & Nematology Department, University of Florida, Gainesville, FL, USA b Department of Agricultural & Biological Engineering, University of Florida, Gainesville, FL, USA c Biological Control Research & Containment Laboratory, University of Florida, Ft. Pierce, FL, USA highlights " Effects of simulated defoliation on growth and biomass accumulation of Hygrophila polysperma were studied. " A plant growth model was developed for prediction of effects of defoliation. " Defoliation significantly influenced growth and biomass accumulation. " The empirical growth model was accurate in simulating plant growth responses. graphical abstract article info Article history: Received 2 July 2011 Accepted 23 November 2011 Available online 1 December 2011 Keywords: Classical biological control Hygrophila polysperma Herbivory simulation Mathematical model abstract Herbivory simulation studies, through mechanical removal of leaf tissue, provide valuable insight about plant compensation and tolerance to defoliation. A mesocosm experiment was conducted to examine the effects of defoliation on growth and biomass accumulation of Hygrophila polysperma and thereby deter- mine the critical level of herbivory necessary to achieve significant reduction in growth of this invasive plant. The data collected during the experiment were used to develop an empirical plant growth model to examine the usefulness of a model-based approach for a priori understanding of plant response to defo- liation. The results of the mesocosm experiment showed that defoliation significantly influenced growth and biomass accumulation of hygrophila. The empirical plant growth model accurately simulated plant growth response to herbivory across treatments. Based on the results of the mesocosm experiment, an insect defoliator that causes complete defoliation of hygrophila at least at monthly intervals may be able to reduce biomass and growth of hygrophila. The ability of the mathematical model to predict the effects of defoliation on hygrophila suggest that it could be a useful tool for the selection of effective biological control agents. Ó 2011 Elsevier Inc. All rights reserved. 1. Introduction The enemy release hypothesis (Williams, 1954) predicts that upon arrival in a new habitat, invasive plants experience a loss of associated natural enemies, which play a significant role in con- trolling the growth and vigor of plants in their native range (Keane and Crawley, 2002). Based on this principle, classical biological control relies on the intentional release of specialized natural enemies to reduce the density and spread of invasive weeds (Muel- ler-Schaerer and Schaffner, 2008). Selection of the most damaging natural enemies enhances the chances of minimizing herbivore- induced compensatory plant growth which can nullify the feeding 1049-9644/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.biocontrol.2011.11.014 ⇑ Corresponding author. Address: Department of Entomology, Texas A&M Uni- versity, 412 Minnie Belle Heep Bldg., 2475 TAMU, College Station, TX 77843-2475, USA. Fax: +1 352 392 0190. E-mail address: abhi06@neo.tamu.edu (A. Mukherjee). Biological Control 60 (2012) 271–279 Contents lists available at SciVerse ScienceDirect Biological Control journal homepage: www.elsevier.com/locate/ybcon