ZooKeys 1044: 797–813 (2021) A peer-reviewed open-access journal doi: 10.3897/zookeys.1044.57849 SHORT COMMUNICATION https://zookeys.pensoft.net Launched to accelerate biodiversity research Species-rich bark and ambrosia beetle fauna (Coleoptera, Curculionidae, Scolytinae) of the Ecuadorian Amazonian Forest Canopy Stephanie A. Dole1, Jiri Hulcr2, Anthony I. Cognato3 1 Department of Entomology, California Academy of Sciences 55 Music Concourse Drive, San Francisco, CA 94118, USA 2 School of Forest Research and Conservation, University of Florida 136 Newins-Ziegler Hall, Gainesville, FL 32611, USA 3 Department of Entomology, Michigan State University 288 Farm Ln. East Lansing, MI 48824, USA Corresponding author: Anthony I. Cognato ([email protected]) Academic editor: M. Alonso-Zarazaga | Received 20 August 2020 | Accepted 3 October 2020 | Published 16 June 2021 http://zoobank.org/D4EB9324-A5B4-48FD-8609-7F260B245010 Citation: Dole SA, Hulcr J, Cognato AI (2021) Species-rich bark and ambrosia beetle fauna (Coleoptera, Curculionidae, Scolytinae) of the Ecuadorian Amazonian Forest Canopy. In: Spence J, Casale A, Assmann T, Liebherr JK, Penev L (Eds) Systematic Zoology and Biodiversity Science: A tribute to Terry Erwin (1940–2020). ZooKeys 1044: 797–813. https://doi.org/10.3897/zookeys.1044.57849 Abstract Canopy fogging was used to sample the diversity of bark and ambrosia beetles (Coleoptera, Curculioni- dae, Scolytinae) at two western Amazonian rainforest sites in Ecuador. Sampling was conducted by Dr Terry Erwin and assistants from 1994–2006 and yielded 1158 samples containing 2500 scolytine speci- mens representing more than 400 morphospecies. Here, we analyze a subset of these data representing two ecological groups: true bark beetles (52 morphospecies) and ambrosia beetles (69 morphospecies). A high percentage of these taxa occurred as singletons and doubletons and their species accumulation curves did not reach an asymptote. Diversity estimates placed the total scolytine species richness for this taxon subset present at the two sites between 260 and 323 species. Theα -diversity was remarkably high at each site, while the apparently high β-diversity was an artifact of undersampling, as shown by a Monte Carlo resampling analysis. This study demonstrates the utility of canopy fogging for the discovery of new scolytine taxa and for approximate diversity assessment, but a substantially greater sampling effort would be needed for conclusive alpha as well as beta diversity estimates. Keywords ambrosia beetles, bark beetles, diversity, neotropical, rainforest, Terry Erwin Copyright Stephanie A. Dole et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 798 Stephanie A. Dole et al. / ZooKeys 1044: 797–813 (2021) Introduction First pioneered by Southwood (1961) in temperate forests and then later adapted for tropical research by numerous others (Lowman and Wittman 1996), canopy fogging methods use insecticide to collect arthropods from the upper architecture of the forest habitat. These methods have been used in surveying arthropod diversity, particularly in lowland rain forests and at several neotropical localities (Erwin 1982; Basset 2001; Rice 2015). These data in part were used to make Erwin’s (1982) bold estimate of 30–50 million arthropod species which was a stark contrast to previous estimates of 1.5–10 million (Erwin 1982). Although this provocative publication produced im- mediate criticism, it initiated focused scientific inquiry for an improved estimate of the number of worldwide arthropod species (e.g., May 1988; Adis 1990; Gaston 1991; Erwin 1991; Ødegaard 2000; Hamilton et al. 2010). For a more than a decade, Erwin and colleagues sampled arthropod diversity in the Ecuadorian Amazon rainforest canopy at two lowland sites with identified trees, separated by 21 km of contiguous primary forest, using a standardized insecticidal fogging protocol (Erwin 1983a, 1983b; Pitman et al. 2001; Erwin et al. 2005). Sampling occurred during dry, wet, and transitional seasons to measure temporal turnover in species composition. Over nine million specimens were collected from these fogging events (Rice 2015) and many new taxa have been described from the specimens (e.g., Erwin 2010). The Scolytinae (Coleoptera, Curculionidae) is comprised of approximately 257 genera containing 6000 species worldwide (Hulcr et al. 2015). Scolytine species feed sub-cortically on a wide variety of woody and herbaceous plants. The typical life cycle of scolytines consists of a brief dispersal flight period after adult emergence, followed by colonization of new hosts. Once a suitable host has been located, adults bore galler- ies into the host tissue, where eggs are laid, and larvae complete their development into the next generation of adults (Kirkendall et al. 2015). Scolytines are divided into two main ecological groups: bark and ambrosia beetles. The degree to which scolytines specialize on specific hosts varies considerably depend- ing on these ecological groups. Bark beetles bore into the phloem of trees, feed on tree tissues, and tend to have more specialized host preferences. Ambrosia beetles bore into the xylem, feed on species of symbiotic fungi, which grow along the walls of their galleries, and tend to have more generalized tree host preferences (Beaver 1979; Hulcr et al. 2007; Kirkendall et al. 2015). The majority of scolytine diversity occurs in tropical regions of the world, and many tropical species remain undescribed (Wood 2007; Hulcr et al. 2015; Smith et al. 2017). The Ecuadorian canopy fogging samples collected in Erwin’s surveys offer a rich source of new scolytine specimens because of observed scolytine species specialization to tree taxa, tree parts, and other microclimate factors (e.g., Hulcr et al. 2007; Kirkendall et al. 2015). In addition, only fewer than 200 species have been recorded for Ecuador (Wood 2007; Martínez et al. 2019; Jordal and Smith 2020), but the Ecuadorian species richness is likely underestimated given the continuous discovery of new species (e.g., Petrov and Flechtmann 2013; Petrov and Mandelshtam 2018; Smith and Cognato, in prep.). Scolytine Amazonian canopy diversity 799 Remarkably few studies have addressed the spatial and temporal turnover of sco- lytine species (β-diversity) (Deyrup and Atkinson 1987; Thunes 1998; Peltonen et al. 1998; Hulcr et al. 2008a, b). The majority of studies have focused on the com- position of the scolytine fauna of temperate regions and examined the distributions of a few economically important species (Deyrup and Atkinson 1987; Jakus 1998; Peltonen et al. 1998; Oliver and Mannion 2001; Gaylord et al. 2006). Several stud- ies in the tropics have attempted to determine the effects of seasonal changes in rainfall and temperature on the composition of scolytine communities (Beaver and Löyttyniemi 1991; Madoffe and Bakke 1995; Morales et al. 2000; Flechtmann et al. 2001; Hulcr et al. 2008a; Sandoval Rodríguez et al. 2017; Martinez et al. 2019; Sanguansub et al. 2020). Studies in Malaysian forests have examined the spatial dis- tribution of scolytines across horizontal (Maeto et al. 1999; Chung 2004) and ver- tical gradients (Maeto and Fukuyama 2003; Simon et al. 2003). Recent studies in Thailand (Hulcr et al. 2008a; Sanguansub et al. 2020) and Papua New Guinea (Hulcr et al. 2008b) have used quantitative sampling to examine scolytine community com- position and attempt to determine the proximate causes of the distribution of species in tropical habitats. Scolytine communities in lowland homogeneous Papua New Guinean rainforests have a low β-diversity, thus contradicting the expected trend of high β-diversity in the tropics. Novotny et al. (2007) similarly demonstrated low species turnover for insect communities when examined on a large scale across Papua New Guinea. In Thailand, two study sites separated by only 5 km were found to have significantly different scolytine species composition (Hulcr et al. 2008a), however the differences were attributed to differences in forest type, elevation, seasonality, mean annual temperature and humidity (Hulcr et al. 2008a; Sanguansub et al. 2020). Giv- en the scenarios above, it is uncertain whether Amazonian forests will produce the same trend of low β-diversity seen in Papua New Guinea or high β-diversity, as was observed between different Thai forests. In tropical ecosystems, an increase in host specificity combined with an increase in plant diversity is often used to explain high levels of species diversity. However, bark and ambrosia beetles show a reverse trend with at least some groups exhibiting lower host specificity in tropical regions. This is largely due to the greater abundance of ambrosial feeding scolytines which, as discussed above, tend to be relative host plant generalists (Beaver 1979), with high symbiont specificity. Nevertheless, most scolyt- ine groups have higher species diversity in tropical regions than they do in temperate ones (Beaver 1979; Deyrup and Atkinson 1987; Hulcr et al. 2015). It is therefore expected that canopy fogging will yield a high number of scolytine species, but that the β-diversity of scolytines across the Amazonian canopy may not necessarily be high. In this study, we use a subset of scolytine specimens representing both the bark beetle and ambrosia beetle ecological groups to assess the diversity of scolytines