Variation in community structure of gall‐inducing insects associated with a tropical plant supports the hypothesis of competition in stressful habitats

Abstract

Environmental factors act as drivers of species coexistence or competition. Mesic environments favor the action of parasites and predators on gall communities, while the factors that determine the structure of gall communities in xeric environments remain unknown. We evaluated the structure of gall communities along an environmental gradient defined by intrinsic plant characteristics, soil fertility, and aridity, and investigated the role of competition as a structuring force of gall communities in xeric environments. We created null models to compare observed and simulated patterns of co‐occurrence of galls and used the C‐score index to assess community aggregation or segregation. We used the NES C‐score (standardized C‐score) to compare patterns of co‐occurrence with parameters of environmental quality. Xeric environments had poorer and more arid soils and more sclerophyllous plants than mesic environments, which was reflected in the distribution patterns of gall communities. Values of the C‐score index revealed a segregated distribution of gall morphospecies in xeric environments, but a random distribution in mesic environments. The low availability of resources for oviposition and the high density of gallers in xeric environments reinforce interspecific competition as an important structuring force for gall communities in these environments.

Gall-inducing arthropods in a Neotropical savanna area in the EPA of Rio Pandeiros (Bonito de Minas, MG, Brazil): effects of plant species richness and super-host abundance

“…Contrary to the expected the galling species richness was not affected by plant species richness and abundance of super host plants, despite the tendency of a positive effect of the abundance of Copaifera oblongifolia on the arthropod gall richness. A possible explanation for these results may be environmental factors, such as environmental stress and soil fertility, which were not measured in the present study, but may also influence the distribution of galling species (Gonçalves-Alvim & Fernandes, 2001;Ramos et al, 2019). On the other hand, we found that galling species per plant species was negatively affected by plant species richness and positively affected by abundance of super-host plants, corroborating our expectations.…”

Diversity of gall-inducing insect associated with a superhost plant species: Plant architecture, resource availability and interspecific interactions

“…Although we have suggested that variation in the availability of oviposition sites may be the generating mechanism of these results, other aspects of the host plant (e.g. tissue nutritional status) and microenvironmental variations should also be considered in future studies as possible variables that may affect the interspecific interactions between herbivores insects (see also Ramos et al 2019).…”

“…Several studies show that ecological interactions that occur between and within trophic levels can shape the structure of gall-inducing insect communities associated with a host plant (Fagundes et al 2005;Costa et al 2016;Ramos et al 2019). Larger plants can be more easily located, provide more oviposition sites for females and shelter from natural enemies (Lawton 1983;Jeffries and Lawton 1984;Araújo et al 2006).…”

“…Recently, several studies have shown that competition can be a driving force herbivore insect community structure, but variation in resource availability and feeding habit of herbivores (i.e. chewing, suckers, miners or gall-inducing insects) can affect the results of interspecific competition on community organization (Cornelissen and Stiling 2008;Ramos et al 2019). For example, although the resource (number of meristems for oviposition) may be abundant for gall-inducing insets, the short time window that surrounds the phenology of the species (i.e.…”

Interspecific competition drives gall‐inducing insect species distribution on leaves of Matayba guianensis Aubl. (Sapindaceae)

“…Many species of gall-inducing insects can affect or be affected by exploitative competition with conspecifics, other gall-inducing insect species, and leaf chewers because they co-occur in space and time on the same host plant using the same resources (Pascual-Alvarado et al, 2008;Cornelissen et al, 2013;Fagundes et al, 2018;Ramos et al, 2019). In addition, gall-inducing insects have the ability to both manipulate and redirect plant growth and development of tissues (Cuevas-Reyes et al, 2004a,b) and modify chemical nutritional quality of their host plants (Pascual-Alvarado et al, 2008;Marini-Filho & Fernandes, 2012).…”