Mexican Gall-Inducing Insects: Importance of Biotic and Abiotic Factors on Species Richness in Tropical Dry Forest

Abstract

In this chapter we provide a brief overview of the major abiotic and biotic factors that influence the diversity of gall-inducing insects in a Mexican tropical dry forest. We tested some current hypotheses (plant species richness, plant structural complexity, plant age, resource concentration and soil fertility) that seek to explain the variation in gall-inducing insect species richness in plant communities of deciduous and riparian habitats. Gall-inducing insect species maintain a great specificity on their host plant species; each gall-inducing insect species is associated with a different plant species. A significant positive correlation was found between gall-inducing insect species richness and plant species richness in both habitats. This suggests that radiation of gall-inducing insect species may be associated with plant species richness. Most of the galling species occurred on trees and shrubs but not on herbs and climbers. The structural complexity of these life forms may provide more potential sites to be colonized by gall insects. The frequency of gall-inducing insects was greater on saplings of most host plants, suggesting that early ontogenetic stages hold more sites with undifferentiated tissues or meristems susceptible to gall induction.