Species richness and host specificity among caterpillar ensembles on shrubs in the Andes of Southern Ecuador

Intra- and interspecific diversity in a tropical plant clade alter herbivory and ecosystem resilience

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems where responses to changes in biodiversity are less predictable and more challenging to assess experimentally. Using large-scale transplant experiments conducted at five neotropical sites, we documented the impacts of changes in intraspecific and interspecific plant richness in the genus Piper on insect herbivory, insect richness, and ecosystem resilience to perturbations in water availability. We found that reductions of both intraspecific and interspecific Piper diversity had measurable and site-specific effects on herbivory, herbivorous insect richness, and plant mortality. The responses of these ecosystem-relevant processes to reduced intraspecific Piper richness were often similar in magnitude to the effects of reduced interspecific richness. Increased water availability reduced herbivory by 4.2% overall, and the response of herbivorous insect richness and herbivory to water availability were altered by both intra- and interspecific richness in a site-dependent manner. Our results underscore the role of intraspecific and interspecific richness as foundations of ecosystem function and the importance of community and location-specific contingencies in controlling function in complex tropical systems.

A database and checklist of geometrid moths (Lepidoptera) from Colombia

Background

Molecular DNA sequence data allow unprecedented advances in biodiversity assessments, monitoring schemes and taxonomic works, particularly in poorly-explored areas. They allow, for instance, the sorting of material rapidly into operational taxonomic units (such as BINs - Barcode Index Numbers), sequences can be subject to diverse analyses and, with linked metadata and physical vouchers, they can be examined further by experts. However, a prerequisite for their exploitation is the construction of reference libraries of DNA sequences that represent the existing biodiversity. To achieve these goals for Geometridae (Lepidoptera) moths in Colombia, expeditions were carried out to 26 localities in the northern part of the country in 2015–2019. The aim was to collect specimens and sequence their DNA barcodes and to record a fraction of the species richness and occurrences in one of the most biodiversity-rich countries. These data are the beginning of an identification guide to Colombian geometrid moths, whose identities are currently often provisional only, being morpho species or operational taxonomic units (OTUs). Prior to the current dataset, 99 Geometridae sequences forming 44 BINs from Colombia were publicly available on the Barcode of Life Data System (BOLD), covering 20 species only.

New information

We enrich the Colombian Geometridae database significantly by including DNA barcodes, two nuclear markers, photos of vouchers and georeferenced occurrences of 281 specimens of geometrid moths from different localities. These specimens are classified into 80 genera. Analytical tools on BOLD clustered 157 of the mentioned sequences to existing BINs identified to species level, identified earlier by experts. Another 115 were assigned to BINs that were identified to genus or tribe level only. Eleven specimens did not match any existing BIN on BOLD and are, therefore, new additions to the database. It is likely that many BINs represent undescribed species. Nine short sequences (< 500bp) were not assigned to BINs, but identified to the lowest taxonomic category by expert taxonomists and with comparisons of type material photos. The released new genetic information will help to further progress the systematics of Geometridae. An illustrated catalogue of all new records allows validation of our identifications; it is also the first document of this kind for Colombian Geometridae. All specimens are deposited at the Museo de Zoología of Universidad de Sucre (MZUS), North Colombia. DNA BINs are reported in this study through dx.doi.org/10.5883/DS-GEOCO, the species occurrences are available on SIB Colombia https://sibcolombia.net/ and the Global Biodiversity Information Facility (GBIF) https://www.gbif.org/ through https://doi.org/10.15472/ucfmkh.

Diversification rates, host plant shifts and an updated molecular phylogeny of Andean Eois moths (Lepidoptera: Geometridae)

Eois is one of the best-investigated genera of tropical moths. Its close association with Piper plants has inspired numerous studies on life histories, phylogeny and evolutionary biology. This study provides an updated view on phylogeny, host plant use and temporal patterns of speciation in Eois. Using sequence data (2776 bp) from one mitochondrial (COI) and one nuclear gene (Ef1-alpha) for 221 Eois species, we confirm and reinforce previous findings regarding temporal patterns of diversification. Deep diversification within Andean Eois took place in the Miocene followed by a sustained high rate of diversification until the Pleistocene when a pronounced slowdown of speciation is evident. In South America, Eois diversification is very likely to be primarily driven by the Andean uplift which occurred concurrently with the entire evolutionary history of Eois. A massively expanded dataset enabled an in-depth look into the phylogenetic signal contained in host plant usage. This revealed several independent shifts from Piper to other host plant genera and families. Seven shifts to Peperomia, the sister genus of Piper were detected, indicating that the shift to Peperomia was an easy one compared to the singular shifts to the Chloranthaceae, Siparunaceae and the Piperacean genus Manekia. The potential for close co-evolution of Eois with Piper host plants is therefore bound to be limited to smaller subsets within Neotropical Eois instead of a frequently proposed genus-wide co-evolutionary scenario. In regards to Eois systematics we confirm the monophyly of Neotropical Eois in relation to their Old World counterparts. A tentative biogeographical hypothesis is presented suggesting that Eois originated in tropical Asia and subsequently colonized the Neotropics and Africa. Within Neotropical Eois we were able to identify the existence of six clades not recognized in previous studies and confirm and reinforce the monophyly of all 9 previously delimited infrageneric clades.

Host Plant Associations and Parasitism of South Ecuadorian Eois Species (Lepidoptera: Geometridae) Feeding on Peperomia (Piperaceae)

The very species-rich tropical moth genus Eois Hübner (Lepidoptera: Geometridae) is a promising model group for studying host plant specialization and adaptive radiation. While most Eois species are assumed to be specialized herbivores on Piper L. species, records on other plant taxa such as Peperomia Ruiz & Pavón (Piperaceae) are still relatively scarce. Moreover, little is known about life history traits of most species, and only a few caterpillars have been described so far. We collected caterpillars associated with Peperomia (Piperaceae) host plants from June 2012 to January 2013 in three elevational bands of montane and elfin rainforests on the eastern slopes of the Andes in southern Ecuador. Caterpillars were systematically searched and reared to the adult stage. We were able to delimitate ten species of Eois on Peperomia by comparison of larval and adult morphology and by using 658 bp fragments of the mitochondrial COI gene (barcode sequences). Three of these species, Eois albosignata (Dognin), Eois bolana (Dognin), and Eois chasca (Dognin), are validly described whereas the other seven taxa represent interim morphospecies, recognized unequivocally by their DNA barcodes, and their larval and adult morphology. We provide information about their host plants, degree of parasitism, and describe the larval stages in their last instar. Additionally, caterpillars and moths are illustrated in color plates. This is the first comparative study dealing with Eois moths whose caterpillars feed on Peperomia hosts.

Many caterpillars in a montane rain forest in Ecuador are not classical herbivores

Lepidopteran caterpillars are typically classified as herbivorous insects. Other feeding associations have been known for a long time but are often neglected in the ecological literature. In samples from 194 shrubs belonging to 16 species of Piperaceae and Asteraceae, which were taken in a montane forest and succession habitats in southern Ecuador, caterpillar assemblages included an unexpectedly large fraction not feeding on the living biomass of their putative ‘host’. Feeding trials revealed them to instead feed on foliose lichens, dead leaves and epiphylls (lichen, algae, bryophytes). These ‘alternative feeders’ accounted for 22.5% of the whole dataset and up to 80% of the caterpillars on individual plant species. Densities of alternative feeders were very similar across shrub species within each plant family, but differed strongly between Asteraceae in succession and Piperaceae in forest habitats. Herbivore caterpillars showed the opposite pattern with strong differences between individual plant species, but overall similar densities on both plant families.