Hypotheses for the richness of gall insects: a review considering the intraespecific, interespecific and community levels

Abstract

In the literature there are several hypotheses that try to explain the patterns of global, regional and local richness of insects associated to plants. These hypotheses can be recognized in different ecological levels, explaining variations in the number of insects associated to individuals or populations of same host species, to different host species, and to different communities. However, the patterns of richness found in each of these levels are result of distinct ecological processes, thus each hypothesis has particularities related to its application depending on the processes considered and on the characteristics of the insect taxa. The objective of this review is to expose the hypotheses that have been used to explain the richness patterns of insects associated to plants, identifying the validity and the use status of each hypothesis in the intraespecific, interespecific, and community levels to gall insect – plant systems. In this review are explicitly enunciated 13 hypotheses considering the levels of ecological organization. This way of view represents a progress because it makes possible an objective analysis of what has been made in the field and a clear visualization of the gaps in the literature. Few hypotheses were enough tested in all levels, mostly in the intraespecific and interespecific levels. Thus it is evident that it is early to reach a general synthesis that explains the patterns of gall insects’ richness in all levels. This review expects, when enunciating the hypotheses in the different levels, to collaborate to the development of the field pointing directions to future studies. Key words: gall insect, richness patters, hypothesis.