Abundance of gall-inducing insect species in sclerophyllous savanna: understanding the importance of soil fertility using an experimental approach

作者：Cuevas Reyes Pablo^*; De Oliveira Ker Fabricio T; Fernandes Geraldo Wilson; Bustamante Mercedes

来源：Journal of Tropical Ecology, 2011, 27: 631-640.

DOI：10.1017/S0266467411000368

• Eremanthus glomerulatus
• gall-inducing insects
• plant fertilization
• sclerophyllous savanna
• soil fertility

Although many studies have now demonstrated that both richness and abundance of gall-inducing insect species are directly and indirectly (via the host plant) influenced by soil quality, the empirical evaluation of it in the field remains anecdotal at best. The effects of soil fertility on richness and abundance of gall-inducing insects associated with a widespread savanna species, Eremanthus glomerulatus, were evaluated under experimental field conditions in Brasilia, central Brazil. The effect of soil fertility on gall-inducing insects species richness was evaluated using three treatments: (1) plots fertilized with nitrogen; (2) plots fertilized with phosphorus; and (3) control plots: soils without fertilization. Species richness of gall-inducing insects (six species of Cecidomyiidae) did not differ among the treatments. Leaves with galls had higher nitrogen concentrations (mean = 15.0 +/- 0.5 mg g(-1)), compared with leaves without galls (mean = 9.0 +/- 0.7 mg g(-1)) on plants that occurred in soils with addition of nitrogen. Similarly, leaves with galls had higher foliar phosphorus concentration (mean = 1.0 +/- 0.04 mg g(-1)) than leaves without galls (mean = 0.6 +/- 0.05 mg g(-1)) in plots with addition of phosphorus. In galled leaves, a negative relationship between gall density and nitrogen concentration was found for one gall-inducing insect species, while three species showed a positive relationship between gall density and leaf nitrogen concentration. A negative relationship between gall density and concentration of leaf phosphorus was observed for four of the six gall-inducing insect species studied. No relationship was found between gall density and leaf nitrogen and phosphorus concentration in ungalled leaves. We argue that foliar nitrogen and phosphorus concentration respond to gall density in galled leaves and therefore, gall-inducing insect species are capable of manipulating their host plant, modifying the foliar nutrients of E. glomerulatus in sclerophyllous savanna.

• 出版日期2011-11