Shredders prefer soft and fungal-conditioned leaves, regardless of their initial chemical traits

Abstract

Through field and laboratory experiments we investigated the effects of leaf traits of two tree species and microbial conditioning on the abundance, biomass, and feeding preference of a typical macroinvertebrate shredder. In the field, we compared the association of Phylloicus (Calamoceratidae, Trichoptera) with two tree species commonly found in riparian zones, which are representative of high and low nutritional quality, respectively: Nectandra megapotamica and Chusquea tenella. In the laboratory, we investigated the feeding preference of Phylloicus using unconditioned leaves and leaves conditioned by aquatic fungi. The same tree species used in the field experiment were used in the laboratory. Initially, C. tenella leaves were proved to be more nutritious and softer, while N. megapotamica leaves were harder and more lignified. The shredders preferred conditioned leaf detritus of reduced toughness (field: C. tenella; laboratory: N. megapotamica, both conditioned for 14 days). These leaf traits seem to be crucial for the choice process of Phylloicus. After 14 days, N. megapotamica leaves showed a decreased toughness associated with the microbial conditioning, which explained its consumption rate by Phylloicus. In both field and laboratory experiments, we found evidence that Phylloicus is a selective feeding shredder, and that the leaf traits, especially leaf structure (e.g., leaf toughness and lignin content), determine its association and preferences.

Leaf litter quality drives the feeding by invertebrate shredders in tropical streams

“…Leaf litter consumption of M. guianensis in Cerrado (33%), and Amazonia (27%) systems was similar to previous study with this plant species in a Cerrado stream (37%; Rezende et al, 2018). Lignin:N is a worldwide proxy for leaf litter decomposability (Zhang et al, 2019), thus lower Lignin:N and consequently lower hardness explains an accelerated fragmentation by Phylloicus (Biasi et al, 2019). Our results corroborate the knowledge that leaf traits are important for the processing of organic matter (Gonçalves et al, 2017; Rezende et al, 2014, 2018).…”

“…Events such as temporal changes of litter quantity and the physical environment have been claimed to affect Phylloicus populations (Leite, Silva, Navarro, Rezende, & Gonçalves Júnior, 2016; Rezende, Santos, Medeiros, & Gonçalves, 2017). As well, intrinsic leaf traits, such as leaf litter size (Rezende et al, 2018), hardness and nutrients (Biasi, Cogo, Hepp, & Santos, 2019; Graça, 2001), lignin (Gessner, 2005), and phenolic concentrations (Moretti, Loyola, Becker, & Callisto, 2009) are factors that denote the leaf litter quality and explain shredders feed preference. However, biological interactions as competition (Rezende et al, 2015) and risk of predation (Navarro, Rezende, & Gonçalves, 2013) can affect negatively the population dynamics of Phylloicus.…”

“…by changes in Amazonia and Cerrado riparian forest composition. Our hypotheses were: (a) Due to the shredder feeding preference for higher quality leaf litter (Biasi et al, 2019; Rincón & Martínez, 2006), a superior consumption will be recorded in more M. guianensis proportion treatments; (b) A higher leaf litter availability will decrease consumption of harder leaf litter, because consumers tends to potentialize the feed in resources that are energetically better for metabolism maintenance (Kaspari, Donoso, Lucas, Zumbusch, & Kay, 2012).…”

Preferencias alimentarias de Phylloicus sp. (Trichoptera: Calamoceratidae) en un río Neotropical de la Sierra Nevada de Santa Marta, Colombia

“…como organismos fragmentadores de la hojarasca en el río Gaira. Éste hecho también fue confirmado por Biasi, Cogo, Hepp & Santos (2019a) en estudios experimentales en un río del sureste de Brasil y bajo condiciones de laboratorio al evaluar la preferencia de hojas por parte de Phylloicus sp.…”

A Importância Da Vegetação Ripária Para O Funcionamento De Riachos: Efeitos Da Qualidade Química E Origem Das Espécies

“…Além disso, os fragmentadores costumam escolher detritos que foram condicionados por comunidades microbianas. Esse processo de condicionamento, principalmente por fungos hifomicetos, transforma os detritos em um recurso mais palatável para os invertebrados detritívoros (BIASI et al, 2019). Em adição, folhas com maiores concentrações de nitrogênio e baixa relação C:N são mais nutritivas (KÖNIG et al, 2014), tendo uma decomposição rápida por serem mais atrativas aos invertebrados fragmentadores.…”