Caterpillar assemblages on Chusquea bamboos in southern Ecuador: abundance, guild structure, and the influence of host plant quality

Abstract

1. Information on the guild structure of foliage‐associated tropical insects is scarce, especially as caterpillars are mostly considered only as herbivores feeding on living leaves. However, many caterpillar species display alternative trophic associations, feeding on dead or withered leaves or epiphylls (‘non‐herbivores’). 2. To determine the contribution of these non‐herbivores, caterpillar communities associated with Chusquea Kunth (Poaceae) in the Andes of southern Ecuador were investigated. Caterpillars were collected at two elevation levels (montane rainforest ∼2000 m and elfin forest at ∼3000 m a.s.l.) and assigned to three feeding guilds (strict herbivores, non‐herbivores, and switchers) based on feeding trials. Foliage quality and leaf area were recorded to test for their influence on guild composition and caterpillar density. 3. Three hundred and eighty‐nine individuals belonging to 175 Lepidoptera species associated with Chusquea bamboos were found. The species richness of caterpillars was similarly high at both elevation levels but varied between feeding guilds. Approximately half (46.5%) displayed an alternative feeding association, i.e. were non‐herbivores (31.1%) or switchers (15.4%). 4. Caterpillar density was nearly two‐fold higher in the elfin forest, but only strict herbivores and switchers increased significantly with elevation. Leaf area positively influenced the density of strict herbivores and switchers; foliage quality only affected strict herbivores. The density of non‐herbivores did not differ significantly between the forest types and was not related to leaf area or foliage quality. 5. The present study underpins that non‐herbivores make up a considerable fraction of caterpillar communities in tropical mountain ecosystems and demonstrates that elevation, foliage quality and available plant biomass further shape feeding guild composition.

DNA barcoding of fogged caterpillars in Peru: A novel approach for unveiling host-plant relationships of tropical moths (Insecta, Lepidoptera)

“…One needs to consider, however, that certain larvae abandon their host-plants searching for a hidden resting place during daytime and mature larvae often leave their food-plant in the last days before pupation looking for a suitable pupation site, sometimes far from their feeding plants. Moreover, in particular in rainwood forests "alternative feeders" may use epiphytes, lianas, lichens, algae, fungi or mosses [14,15], and in our fogging approach pitfalls are possible through collateral fogging of larvae from neighboring trees. Gut content analysis can shed light on true feeding biology.…”

Moth assemblages in Costa Rica rain forest mirror small‐scale topographic heterogeneity

“…Moreover, due to the high relative humidity in the forest understory along the creeks, leaves are very quickly overgrown by epiphylls (lichens, algae, and fungi) and hence not acceptable to many herbivores which predominantly prefer fresh leaves (Coley & Barone, ; Coley, Kursar & Machado, ; Toomey, Roberts & Nelson, ). Recent studies have shown that, in tropical mountain forests, caterpillars that feed on dead plant parts or graze on epiphylls play a very substantial role (Bodner, Brehm & Fiedler, ; Seifert, Lehner, Bodner & Fiedler, ), but it remains to be shown how important these particular caterpillar guilds are in tropical lowlands. Furthermore, the moist microclimate of the creek forests might facilitate the activity and spread of pathogens, thereby increasing early life stage mortality and finally leading to a lower moth abundance (Hilt, Brehm & Fiedler, ; Intachat, Holloway & Staines, ): (b) Lower plant species richness at creek sites might constrain moth species richness.…”

Remote sensing improves prediction of tropical montane species diversity but performance differs among taxa

“…As suggested in Stein et al (2014), habitat heterogeneity might be more important for certain herbivores than climatic or topographical heterogeneity since different clades of moth species have developed distinct biological features to cope with environmental factors such as temperature (Braga and Diniz, 2015). By contrast, arctiinae moths comprise a speciose clade of which a large amount of caterpillar species are not classical herbivores as they feed on dead or withered leaves or epiphylls (Bodner et al, 2015;Seifert et al, 2016). Therefore, it is not surprising that neither topographical nor texture metrics as proxies for habitat heterogeneity (dominated by tree crowns) were able to model the species richness of arctiinae moths successively.…”