Diversity of insects associated with two common plants in the Brazilian Cerrado: Responses of two guilds of herbivores to bottom-up and top-down forces

Abstract

The Trophic Cascade Theory has been used to explain the organization of herbivorous insect communities in tropical ecosystems. In addition, the insect community associated with a species of plant can also be determined by the geographical distribution and taxonomic isolation of the plant. In this study, the following predictions about the number of herbivores associated with particular host plants were tested: (i) plant species belonging to large taxonomic groups with broad geographical distributions have a higher number, (ii) the abundance of ants negatively affects herbivore insect diversity, (iii) local plant diversity positively affects chewing herbivore diversity and (iv) local abundance of a specifi c host plant positively affects the diversity of sucking herbivores. The samples of insect herbivores were collected from 32 plants (16 plants of Erythroxylum suberosum and 16 of Qualea parvifl ora) by beating. A total of 71 ants (13 species) and 158 herbivorous insects (90 species) were collected from these two species of plants. The richness and abundance of the insect herbivores collected from E. suberosum differed from those collected from Q. parvifl ora. The abundance of ants negatively affected the diversity of sucking insects associated with E. suberosum. In addition, the interaction between the variables total plant richness per plot and ant abundance affected the diversity of chewing insects associated with E. suberosum. The density of Q. parvifl ora per plot affected the diversity of associated sucking insects. In addition, the interaction of the variables abundance of ants and abundance of Q. parvifl ora infl uenced the diversity of chewing insects. Our results indicate that there is no predominance of bottom-up or top-down forces in the organization of herbivorous insect communities in this area of tropical savanna, but the roles of these forces on insect communities are guild-dependent.

Comparing the plant–herbivore network topology of different insect guilds in Neotropical savannas

“…Galling insect networks were less modular and more specialised than exophagous insect networks, and sucking insect networks were more specialised than chewing insect networks. These results corroborate previous studies, showing that endophagous and exophagous herbivores have different patterns of interactions with their host plants (Gaston et al ., ; Araújo ; Kuchenbecker & Fagundes, ). In addition, we also found that network connectance and specialisation depend on network size, as already described in previous studies (Dunne et al ., ).…”

“…Another factor that may have contributed to the modular structure in exophage networks is the large number of singleton species (Novotný & Basset, ). The occurrence of rare species is common in communities of tropical insect herbivores (Price et al ., ; Lewinsohn et al ., ; Novotný & Basset, ), including Neotropical savannas (Kuchenbecker & Fagundes, ), and may increase the modularity in plant–herbivore networks (Dormann & Strauss, ).…”

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

“…The structure of gall‐inducing insect communities can be determined by environmental factors (Blanche, ; Butterill & Novotny, ; Craig, Itami, & Craig, ; Cuevas‐Reyes, Quesada, & Oyama, ; da Costa, de Siqueira Neves, de Oliveira Silva, & Fagundes, ; Price, ), by top‐down (Fagundes, Neves, & Fernandes, ; Price, ) or bottom‐up (Egan & Ott, ; Espírito‐Santo, de S. Neves, Andrade‐Neto, & Fernandes, ; Hunter & Price, ; Malinga, Valtonen, Nyeko, Vesterinen, & Roininen, ) mechanisms, and by interactions that occur within the same trophic level, such as interspecific competition (Cornelissen et al, ; Fagundes & Fernandes, ; Fagundes et al, ). Studies have reported that the results of interspecific interactions involving phytophagous insects can be habitat‐dependent (Kuchenbecker & Fagundes, ).…”

Positive outcomes between herbivore diversity and tree survival: Responses to management intensity in a Patagonian forest

“…Our study shows a strong positive correlation between arthropod herbivore guild diversity and arthropod herbivory rates for N. obliqua. We found no studies analyzing the relation between herbivore guild diversity and herbivore rates, but there are some examples of positive relations between herbivore diversity and abundance (Neves et al, 2010(Neves et al, , 2014Kuchenbecker & Fagundes, 2018). Guild diversity could enhance herbivore abundance (Lewinsohn et al, 2005) potentially explaining greater leaf consumption rates (Siemann et al, 1996;Novotny et al, 2010Novotny et al, , 2012Pinheiro et al, 2016;Muiruri et al, 2019), because of niche complementarity (Gable et al, 2012;Valencia-Cuevas and Tovar-Sánchez, 2015).…”