Fire effects on insect herbivores in an oak savanna: the role of light and nutrients

Abstract

1. Environmental heterogeneity created by prescribed burning provided the context for testing whether the distribution of an oak specialist (the lace bug, Corythuca arcuata ) could be explained by stoichiometric mismatches between herbivore and host plant composition.2. Field observations showed that lace bug density was seven-fold higher in frequently burned than in unburned units.3. Lace bug density did not increase with leaf nutrient concentrations, but was instead associated with higher light levels, higher concentrations of leaf carbon (C), lignin and total phenolics, and lower levels of cellulose. In addition, lace bugs reared on high-light leaves had higher levels of survivorship than those fed on low-light leaves.4. Sampling restricted to full-sun leaves was used to test whether fire-related changes in leaf nitrogen (N) and phosphorus (P) concentrations have a secondary influence on lace bug success. This sampling provided only limited evidence for nutrient limitation, as decreases in leaf N and P were associated with an increase in lace bug mass but a decrease in density.5. It is concluded that burning probably promotes lace bug population growth by increasing canopy openness, light penetration, and the availability of C-based metabolites, and thus simple stoichoimetric mismatches between herbivores and host plants are not of primary importance in this system.

How do frequent fires in the Cerrado alter the lepidopteran community?

“…Arthropods seem to be affected more by frequent fires than infrequent fires. For example, in one study, the densities of lace bugs, which are burned oak specialists, were more than seven times higher on trees in frequently burned units than on those in unburned units, and their presence was associated with higher light levels, changes in leaf carbon quality, and reductions in leaf nitrogen concentration (Kay et al 2007).…”

“…Despite the fact that fire is considered to be an important disturbance in many kinds of tropical savanna, fire can also be an important tool for ecosystem management in many biomes throughout the world (Andersen and Müller 2000). Frequent fires are inevitable in tropical savannas because dry fuels build up each year (Kay et al 2007).…”

Short-Term Effects of Prescribed Burning on Ant (Hymenoptera: Formicidae) Assemblages in Ozark Forests

“…Ant activity on burned sites was conspicuously lower in the weeks after the fire, suggesting that burned habitats are suboptimal for foraging (Farji-Brener et al 2002), perhaps because of lack of food or cover, or ash toxicity (e.g., Edwards and Schwartz 1981). Fires reduce leaf Htter depth to near zero and increase light in the understory (Rieske et al 2002, Kay et al 2007), thus soil-and litter-dwelling ants are more highly exposed while foraging after a fire, potentially leading to higher desiccation rates or increased prédation by ant-specialist foragers (e.g., Torgensen 1995).…”

Multiple host use by a sap-sucking membracid: population consequences of nymphal development on primary and secondary host plant species

“…Outbreaks on fiddlewood are normally associated with defoliation of the affected stems and a general decline in host quality (Palmer et al 2004). Host plant physiological condition, in turn, may affect the oviposition rate, development time and survival of insect herbivores (Gols et al 2007;Jonas and Joern 2008;Kay et al 2007;Sipura and Tahvanainen 2000;Van Hezewijk et al 2008), and may help explain patterns of host use in particular situations.…”