The high dependence of herbivorous insects on their host plants implies that plant invaders can affect these insects directly, by not providing a suitable habitat, or indirectly, by altering host plant availability. In this study, we sampled Asteraceae flower heads in cerrado remnants with varying levels of exotic grass invasion to evaluate whether invasive grasses have a direct effect on herbivore richness independent of the current disturbance level and host plant richness. By classifying herbivores according to the degree of host plant specialization, we also investigated whether invasive grasses reduce the uniqueness of the herbivorous assemblages. Herbivorous insect richness showed a unimodal relationship with invasive grass cover that was significantly explained only by way of the variation in host plant richness. The same result was found for polyphagous and oligophagous insects, but monophages showed a significant negative response to the intensity of the grass invasion that was independent of host plant richness. Our findings lend support to the hypothesis that the aggregate effect of invasive plants on herbivores tends to mirror the effects of invasive plants on host plants. In addition, exotic plants affect specialist insects differently from generalist insects; thus exotic plants affect not only the size but also the structural profile of herbivorous insect assemblages. © 2010 Springer-Verlag.165410511062Almeida, A.M., Fonseca, C.R., Prado, P.I., Almeida-Neto, M., Diniz, S., Kubota, U., Braun, M.R., Lewinsohn, T.M., Diversidade e ocorrência de Asteraceae em cerrados de São Paulo (2005) Biota Neotrop, 5, pp. 27-43Almeida, A.M., Fonseca, C.R., Prado, P.I., Almeida-Neto, M., Diniz, S., Kubota, U., Braun, M.R., Lewinsohn, T.M., Assemblages of endophagous insects on Asteraceae in São Paulo cerrados (2006) Neotrop Entomol, 35, pp. 458-468Almeida-Neto, M., Prado, P.I., Kubota, U., Bariani, J.M., Aguirre, G.H., Lewinsohn, T.M., Invasive grasses and native Asteraceae in the Brazilian Cerrado (2010) Plant Ecol, 209, pp. 109-122Arbuckle, J.L., (2003) Amos User's Guide, 5.0 Update, , Chicago: SmallwatersBartomeus, I., Vilà, M., Santamaría, L., Contrasting effects of invasive plants in plant-pollinator networks (2008) Oecologia, 155, pp. 761-770Baruch, Z., Ludlow, M.M., David, R., Photosynthetic responses of native and introduced C4 grasses from Venezuela savannas (1985) Oecologia, 67, pp. 388-393Brändle, M., Amarell, U., Auge, H., Klotz, S., Brandl, R., Plant and insect diversity along a pollution gradient: understanding richness across trophic levels (2001) Biodivers Conserv, 10, pp. 1497-1511Braun, M.R., Almeida-Neto, M., Loyola, R.D., Prado, A.P., Lewinsohn, T.M., New host-plant records for neotropical agromyzids (Diptera: Agromyzidae) from Asteraceae flower heads (2008) Neotrop Entomol, 37, pp. 97-99Brooks, M.L., D'Antonio, C.M., Richardson, D.M., Effects of invasive alien species on fire regimes (2004) Bioscience, 54, pp. 677-688Brown, J.H., On the relationship between abundance and distribution of species (1984) Am Natur, 124, pp. 255-279Brown, V.K., Hyman, P.S., Successional communities of plants and phytophagous Coleoptera (1986) J Ecol, 74, pp. 963-975Burnham, K.P., Anderson, D.R., (2002) Model Selection and Multimodel Inference: A Practical-Theoretic Approach, , 2nd edn., New York: SpringerCharrette, N.A., Cleary, D.F.R., Mooers, A., Range-restricted, specialist bornean butterflies are less likely to recover from enso-induced disturbance (2006) Ecology, pp. 2330-2337Davies, K.F., Margules, C.R., Lawrence, J.F., A synergistic effect puts rare, specialized species at greater risk of extinction (2004) Ecology, 85, pp. 265-271de Groot, M., Kleijn, D., Jogan, N., Species groups occupying different trophic levels respond differently to the invasion of semi-natural vegetation by Solidago canadensis (2007) Biol Conserv, 136, pp. 612-617Didham, R.K., Tylianakis, J.M., Hutchison, M.A., Ewers, R.M., Gemmell, N.J., Are invasive species the drivers of ecological changes? (2005) Trends Ecol Evol, 20, pp. 470-474Durigan, G., Siqueira, M.F., Franco, G.A.D.C., Threats to the Cerrado remnants of the state of São Paulo, Brazil (2007) Sci Agric, 64, pp. 355-363Ehrenfeld, J.G., Effects of exotic plant invasions on soil nutrient cycling processes (2003) Ecosystems, 6, pp. 503-523Ernst, C.M., Cappuccino, N., The effect of an invasive alien vine, Vincetoxicum rossicum (Asclepiadaceae), on arthropod populations in Ontario old fields (2005) Biol Invas, 7, pp. 417-425Filgueiras, T.S., Herbaceous plant communities (2002) The Cerrados of Brazil: Ecology and Natural History of a Neotropical Savanna, pp. 121-139. , P. S. Oliveira and R. J. Marquis (Eds.), New York: Columbia University PressFonseca, C.R., Prado, P.I.K., Almeida-Neto, M., Flowerheads and their insects: food web structure along a fertility gradient of Cerrado (2005) Ecol Entomol, 30, pp. 36-46Fournier, L.A., Quantitative method for measuring phenological characteristics of trees (1974) Turrialba, 24, pp. 422-423Gerber, E., Krebs, C., Murrell, C., Moretti, M., Rocklin, R., Schaffner, U., Exotic invasive knotweeds (Fallopia spp.) negatively affect native plant and invertebrate assemblages in European riparian habitats (2008) Biol Conserv, 141, pp. 646-654Grace, J.B., (2006) Structural Equation Modeling and Natural Systems, , Cambridge: Cambridge University PressGrace, J.B., Keeley, J.E., A structural equation model analysis of postfire plant diversity in California shrublands (2006) Ecol Appl, 16, pp. 503-514Gratton, C., Denno, R.F., Restoration of arthropod assemblages in a Spartina salt marsh following removal of the invasive plant Phragmites australis (2005) Restor Ecol, 13, pp. 358-372Haddad, N.M., Tilman, D., Haarstad, J., Ritchie, M., Knops, J.M.H., Contrasting effects of plant richness and composition on insect communities: a field experiment (2001) Am Nat, 158, pp. 17-35Hawkes, C.V., Wren, I.F., Herman, D.J., Firestone, M.K., Plant invasion alters nitrogen cycling by modifying the soil nitrifying community (2005) Ecol Lett, 8, pp. 976-985Heleno, R.H., Ceia, R.S., Ramos, J.A., Memmott, J., Effects of alien plants on insect abundance and biomass: a food-web approach (2008) Conserv Biol, 23, pp. 410-419Hobbs, R.J., Huenneke, L.F., Disturbance, diversity and invasion: implications for conservation (1992) Conserv Biol, 6, pp. 324-337Hoffmann, W.A., Haridasan, M., The invasive grass, Melinis minutiflora, inhibits tree regeneration in a Neotropical savanna (2008) Austral Ecol, 32, pp. 29-36Hoffmann, W.A., Lucatelli, V.M.P.C., Silva, F.J., Azeuedo, I.N.C., Marinho, M.S., Albuquerque, A.M.S., Lopes, A.O., Moreira, S.P., Impact of the invasive alien grass Melinisminutiflora at the savanna-forest ecotone in the Brazilian Cerrado (2004) Divers Distrib, 10, pp. 99-103Hughes, J.B., The scale of resource specialization and the distribution and abundance of lycaenid butterflies (2000) Oecologia, 123, pp. 375-383Hunter, M.D., Price, P.W., Playing chutes and ladders: heterogeneity and the relative roles of bottom-up and top-down forces in natural communities (1992) Ecology, 73, pp. 724-732Hutchinson, G.E., Homage to Santa Rosalia, or why are there so many kinds of animals (1959) Am Nat, 93, pp. 145-159Jonsen, I.D., Fahrig, L., Response of generalist and specialist insect herbivores to landscape spatial structure (1997) Land Ecol, 12, pp. 185-197Kitahara, M., Sei, K., Fujii, K., Patterns in the structure of grassland butterfly communities along a gradient of human disturbance: further analysis based on the generalist/specialist concept (2000) Popul Ecol, 42, pp. 135-144Klink, C.A., Competition between the African grass Andropogon gayanus Kunth and the native cerrado grass Schizachyrium tenerum Nees (1996) Rev Bras Bot, 19, pp. 11-15Koh, L.P., Sodhi, N.S., Brook, B.W., Ecological correlates of extinction proneness in tropical butterflies (2004) Conserv Biol, 18, pp. 1571-1578Köppen, W., (1948) Climatología, , México: Fondo de Cultura EconómicaLawton, J.H., Range, population abundance and conservation (1993) Trends Ecol Evol, 8, pp. 409-413Leibold, M.A., Holyoak, M., Mouquet, N., Amarasekare, P., Chase, J.M., Hoopes, M.F., Holt, R.D., Gonzalez, A., The metacommunity concept: a framework for multiscale community ecology (2004) Ecol Lett, 7, pp. 601-613Levine, J.M., Vilà, M., D'Antonio, C.M., Dukes, J.S., Grigulis, K., Lavorel, S., Mechanisms underlying the impacts of exotic plant invasions (2003) Proc Biol Sci, 270, pp. 775-781Lewinsohn, T.M., Insects in flower heads of Asteraceae in Southeast Brazil: a tropical case study on species richness (1991) Plant-Animal Interactions: Evolutionary Ecology in Tropical and Temperate Regions, pp. 525-560. , P. W. Price, T. M. Lewinsohn, G. W. Fernandes, and W. W. Benson (Eds.), New York: Wiley/InterscienceLewinsohn, T.M., Roslin, T., Four ways towards tropical herbivore megadiversity (2008) Ecol Lett, 11, pp. 398-416Lewinsohn, T.M., Novotny, V., Basset, Y., Insects on plants: diversity of herbivore assemblages revisited (2005) Annu Rev Ecol Evol Syst, 36, pp. 597-620Litt, A.R., Steidl, R.J., Insect assemblages change along a gradient of invasion by a nonnative grass (2010) Biol Invas, 12, pp. 3449-3463Lozon, J.D., Macisaac, H.J., Biological invasions: are they dependent on disturbance? (1997) Environ Rev, 5, pp. 131-144Macdougall, A.S., Turkington, R., Are invasive species the drivers or passengers of change in degraded ecosystems? (2005) Ecology, 86, pp. 42-55Mack, M.C., D'Antonio, C.M., Impacts of biological invasions on disturbance regimes (1998) Trends Ecol Evol, 13, pp. 195-198Mack, R.N., Simberloff, D., Lonsdale, W.M., Evans, H., Clout, M., Bazzaz, F.A., Biotic invasions: causes, epidemiology, global consequences, and control (2000) Ecol Appl, 10, pp. 689-710May, R.M., The dimensions of life on earth (2000) Nature and Human Society: The Quest for a Sustainable World, pp. 30-45. , P. H. Raven and T. Williams (Eds.), Washington: National Academy PressMcKinney, M.L., Extinction vulnerability and selectivity: combining ecological and paleontological views (1997) Annu Rev Ecol Syst, 28, pp. 495-516McKinney, M.L., Lockwood, J.L., Biotic homogenization: a few winners replacing many losers in the next mass extinction (1999) Trends Ecol Evol, 14, pp. 450-453(2005) Ecosystems and Human Well-Being: Synthesis, , Millennium Ecosystem Assessment (MEA), Washington: Island PressMistry, J., Fire in the cerrado (savannas) of Brazil: an ecological review (1998) Progr Phys Geogr, 22, pp. 425-448Mistry, J., Berardi, A., Assessing fire potential in a Brazilian savanna nature reserve (2005) Biotropica, 37, pp. 439-451Mittermeier, R.A., Gil, P.R., Hoffmann, M., (2005) Hotspots Revisited: Earth's Biologically Richest and Most Endangered Terrestrial Ecoregions, , R. A. Mittermeier, P. R. Gil, and M. Hoffmann (Eds.), Washington: Conservation InternationalMurdoch, W.W., Peterson, C.H., Evans, F.C., Diversity and pattern in plants and insects (1972) Ecology, 53, pp. 819-829Novotny, V., Miller, S.E., Hulcr, J., Drew, R.A.I., Basset, Y., Janda, M., Setliff, G.P., Weiblen, G.D., Low beta diversity of herbivorous insects in tropical forests (2007) Nature, 448, pp. 692-695Ødegaard, F., Diserud, O.H., Østbye, K., The importance of plant relatedness for host utilization among phytophagous insects (2005) Ecol Lett, 8, pp. 612-617Odum, E.P., The strategy of ecosystem development (1969) Science, 164, pp. 262-270Ortega, Y.K., Pearson, D.E., Weak vs. strong invaders of natural plant communities: assessing invasibility and impact (2005) Ecol Appl, 15, pp. 651-661Pearson, D.E., Invasive plant architecture alters trophic interactions by changing predator abundance and behavior (2009) Oecologia, 159, pp. 549-558Pivello, V.R., Carvalho, V.C.M., Lopes, P.F., Peccinini, A.A., Rosso, S., Abundance and distribution of native and alien grasses in a "cerrado" Brazilian Savanna biological reserve (1999) Biotropica, 31, pp. 71-82Pivello, V.R., Shida, C.N., Meirelles, S.T., Alien grasses in Brazilian savannas: a threat to the biodiversity (1999) Biodivers Conserv, 8, pp. 1281-1294Pöyry, J., Luoto, M., Paukkunen, J., Pykälä, J., Raatikainen, K., Kuussaari, M., Different responses of plants and herbivore insects to a gradient of vegetation height: an indicator of the vertebrate grazing intensity and successional age (2006) Oikos, 115, pp. 401-412Prado, H., Oliveira, J.B., Almeida, C.L.A., (1981) Levantamento Pedológico Semidetalhado Do Estado De São Paulo: Quadrícula De São Carlos Mapa Escala, 1 (100), p. 000Prado, P.I., Almeida, A.M., Lewinsohn, T.M., Norrbom, A.L., Buys, B.D., Macedo, A.C., Lopes, M.B., The fauna of Tephritidae (Diptera) from capitula of Asteraceae in Brazil (2002) Proc Entomol Soc Wash, 104, pp. 1006-1027Quinn, R.M., Gaston, K.J., Roy, D.B., Coincidence between consumer and host occurrence: Macrolepidoptera in Britain (1997) Ecol Entomol, 22, pp. 197-208R: A language and environment for statistical computing (2006) R Foundation For Statistical Computing, , http://www.R-project.org, R Development Core Team, Vienna, Austria. ISBN 3-900051-07-0Ratter, J.A., Ribeiro, J.F., Bridgewater, S., The Brazilian cerrado vegetation and threats to its biodiversity (1997) Ann Bot, 80, pp. 223-230Sano, S.M., Almeida, S.P., Ribeiro, J.F., (2008) Cerrado: Ecologia E Flora, 2. , Brasília: EmbrapaSiemann, E., Tilman, D., Haarstad, J., Ritchie, M., Experimental tests of the dependence of arthropod diversity on plant diversity (1998) Am Nat, 152, pp. 738-750Siemann, E., Haarstad, J., Tilman, D., Dynamics of plant and arthropod diversity during old field succession (1999) Ecography, 22, pp. 406-414Southwood, T.R.E., Brown, V.K., Reader, P.M., The relationships of plant and insect diversity in succession (1979) Biol J Linn Soc, 12, pp. 327-348Strong, D.R., Lawton, J.H., Southwood, T.R.E., (1984) Insects on Plants, , Oxford: BlackwellTallamy, D.W., Do alien plants reduce insect biomass? (2004) Conserv Biol, 18, pp. 1689-1692Valtonen, A., Jantunen, J., Saarinen, K., Flora and lepidoptera fauna adversely affected by invasive Lupinus polyphyllus along road verges (2006) Biol Conserv, 133, pp. 389-396Vitousek, P.M., Mooney, H.A., Lubchenco, J., Melillo, J.M., Human domination of earth's ecosystems (1997) Science, 277, pp. 494-499White, R., Murray, S., Rohweder, M., (2000) Pilot Analysis of Global Ecosystems: Grassland Ecosystems Technical Report, , Washington: World Resources InstituteYoshioka, A., Kadoya, T., Suda, S., Washitani, I., Impacts of weeping lovegrass (Eragrostis curvula) invasion on native grasshoppers: responses of habitat generalist and specialist species (2010) Biol Invas, 12, pp. 531-539Zwölfer, H., Evolutionary and ecological relationships of the insect fauna of thistles (1988) Annu Rev Entomol, 33, pp. 103-122