Feeding-Induced Changes in Plant Quality Mediate Interspecific Competition between Sap-Feeding Herbivores

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Feeding-induced plant resistance is a well-documented phenomenon for leafchewing insects. Furthermore, feeding-induced resistance provides the mechanistic basis for many cases of delayed interspecific competition, whereby previous feeding by one species diminishes the performance of other herbivores which attack the same plant later in the season. This phenomenon, however, has been very poorly investigated for sap-feeding insects. The results we present here for salt marsh-inhabiting planthoppers (Prokelisia dolus and P. marginate) provide one of the few known examples of delayed, plant-mediated interspecific competition between two sap-feeding insects.Three lines of experimental evidence from the laboratory, field cages, and open field plots provide support for the detrimental effects of previous feeding by one planthopper species on the subsequent survival and performance of the other. Laboratory experiments showed that prior feeding on cordgrass by one congener resulted in reduced performance of the other in the following generation. However, the effect was asymmetric. Prior feeding by P. dolus resulted in prolonged development and reduced body size (a correlate of fecundity) in P. marginate, whereas only development was protracted in P. dolus when plants were previously exposed to P. marginate. Consequently, P. dolus appears to be the superior competitor in the context of delayed, plant-mediated interactions. The negative effects of previous feeding by P. dolus on the development time, body size, and survival of P. marginate obtained in the laboratory were confirmed both in cages and on cage-free islets of cordgrass in the field. Feeding-induced reductions in host-plant quality by P. dolus may provide additional impetus for P. marginate to migrate from shared habitats on the high marsh to nutritionally superior plants in the low marsh rarely occupied by P. dolus.The mechanism underlying the delayed competitive effects between Prokelisia planthoppers is most likely diminished plant nutrition, because feeding by P. dolus significantly reduces the concentration of essential amino acids in cordgrass. The asymmetry of plantmediated competition between the Prokelisia species may be due to the ability of P. dolus to better tolerate feeding-depleted levels of plant nitrogen via compensatory feeding.Even though these two planthoppers do not suffer significant fitness reductions during contemporaneous interactions, they compete severely in the context of feeding-induced plant resistance which is expressed later in the season. This result, coupled with the fact that mos...

Trade-off in investment between dispersal and ingestion capability in phytophagous insects and its ecological implications

“…Thus, wing-form differences in head morphology, which are likely associated with feeding capability, are far greater in the sedentary species (>90% brachyptery), which must contend with on-site fluctuations in host plant quality. Similarly, wing form differences in thorax morphology are exaggerated in the migratory species, which copes with deteriorating plant nutrition via dispersal (Denno 1994;Denno et al 2000). These latter data are consistent with the argument that selection for dispersal favors a positive correlation between the proportion of flight-capable adults in the population and the flight capability (investment in flight morphology) of the macropterous morph (Fairbairn and Desranleau 1987;Fairbairn and Butler 1990;Roff and Fairbairn 1991;Fairbairn 1994 than macropters from species that are largely brachypterous (Fairbairn and Desranleau 1987;Fairbairn and Butler 1990).…”

“…Moreover, the competitive superiority of P. dolus over P. marginata is likely attributable to its greater commitment to cibarial muscle mass and increased ability to compensate for declining plant nitrogen via enhanced ingestion. For example, in mixed-species crowds, not only does P. dolus contribute more to feeding-induced declines in plant nitrogen but it also tolerates such declines better and experiences fewer performance and fitness costs (Olmstead et al 1997;Denno et al 2000). Thus, competitive superiority is associated with feeding compensation and tolerance of low plant nitrogen, whereas poor competitive ability is linked with intolerance of depleted nitrogen and high mobility .…”

“…P. dolus, however, has the ability to withstand nitrogen-deficient plants better than P. marginata (Huberty 2005). Thus, existing data suggest that nitrogen is limiting for both Prokelisia species, but that P. marginata copes with spatial changes in host-plant quality by dispersal to more favorable habitats, whereas P. dolus is able to remain on site and persist through periods of inadequate plant nutrition (Cook and Denno 1994;Denno et al 2000).…”

Microbial impacts on plant-herbivore interactions: the indirect effects of a birch pathogen on a birch aphid

“…Denno et al 1995;Denno et al 2000;Fisher et al 2000;Kessler and Baldwin 2001). Such plant-mediated interactions can occur between insects at different trophic levels, for instance plant-mediated attraction of natural enemies (Dicke 1994;Pare et al 1998;Kessler and Baldwin 2001), and also between insect herbivores feeding on the same plant (Fisher et al 2000;Petersen and Sandstrom 2001;Johnson et al 2002).…”

Spatial heterogeneity in the relative impacts of foliar quality and predation pressure on red oak, Quercus rubra, arthropod communities

“…Species composition of mid-trophic level arthropod communities is often diverse and not all herbivores respond the same way to the same ecological pressures (Denno et al 2000;Forkner and Hunter 2000). Variation in susceptibility of herbivores to predation can depend on herbivore ontogeny (Chase 2003;Hawkins et al 1997;Murdoch et al 2006), feeding strategy (Cornell and Hawkins 1995), and defense mechanisms (Muller and Brakefield 2003).…”