Plant phenological asynchrony and community structure of gall‐inducing insects associated with a tropical tree species

Abstract

The dynamics of occurrence of target organs in plant populations produces windows of opportunity that directly and indirectly affect the structure of herbivore communities. However, mechanisms that drive herbivore specialization between resource patches are still poorly known. In this study, we tested three hypotheses related to variation in host plant phenology and community structure (i.e., composition, richness, and abundance) of gall‐forming species: (a) plants with early leaf‐flushing in the season will have greater vegetative growth and high contents of secondary chemical compounds; (b) gall‐inducing insect community structure changes among temporary resource patches of the host; and (c) interspecific competition is a probable mechanism that drives gall‐inducing insect community structure on Copaifera langsdorffii. We monitored daily a total of 102 individuals of the super‐host C. langsdorffii from August 2012 to May 2013, to characterize the leaf flushing time of each host plant. The leaf flushing time had a positive relationship with the number of folioles per branch and a negative relationship with branch growth. We sampled a total of 4,906 galls belonging to 24 gall‐inducing insect species from 102 individuals of C. langsdorffii. In spite of some gall‐inducing species presented high abundance on early leaf‐flushing plants, direct and indirect effects of plant phenology on galling insect abundance was species dependent. At the community level, our study revealed that the quality and quantity of plant resources did not affect the richness and abundance of gall‐inducing insects associated with C. langsdorffii. However, the richness and composition of gall‐inducing species varied according to the variation in leaf flushing time of the host plant. The results of null model analysis showed that galls co‐occurrence on C. langsdorffii trees differ more than expected by chance and that interspecific competition can be one potential mechanism structuring this gall‐inducing insect community.

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

“…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. period of plant leaf-budding and adult emergence of gall-inducing insects) may limit temporally the number of meristems available for female oviposition, generating a dispute for sites more suitable for oviposition between different species (Cornelissen et al 2013;Fagundes et al 2018).…”

“…Females of gall-inducing insects show high oviposition specificity with the taxa and the organ/tissue of the host plant (Carneiro et al 2009). The females generally oviposit in meristematic tissues that have restricted temporal distribution, especially in seasonal environments (Egan and Ott 2007;Fagundes et al 2018). Chemical and structural changes occur in tissues near the oviposition site, resulting in the formation of structures known as galls or cecidia that house the immature insect within it (Ozaki et al 2014).…”

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, ).…”

“…Among ecological mechanisms, the actions of parasites and predators (third trophic level) are thought to be less effective at regulating gall‐inducing insect diversity in xeric habitats, thus leading to greater diversity of gallers in such habitats (Castellanos, Cuevas‐Reyes, Rios‐Casanova, Oyama, & Quesada, ). Studies have also shown that plants growing on water‐ and nutrient‐deprived soils are more sclerophyllous (Poorter, Niinemets, Poorter, Wright, & Villar, ) and accumulate higher levels of chemical compounds (Fagundes et al, ). Thus, internal‐feeding gall‐inducing insects attacking such plants would experience greater protection from their natural enemies (Hardy & Cook, ; Ribeiro & Basset, ).…”

“…Soon after oviposition, hatched larvae of galling insects induce rapid morphological and physiological changes in host plant tissue, draining resources for their own development (Höglund, ; Ollerstam, Rohfritsch, Höglund, & Larsson, ), which potentially interferes with the oviposition behavior of females of other gall‐inducing insects species (Cornelissen et al, ). Because they are sessile and highly specific, galls are excellent models for understanding the effects of interspecific competition on community structuring (Cornelissen et al, ; Fagundes et al, ).…”