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1. An improved method for utilizing high‐throughput amplicon sequencing to determine the diets of insectivorous animals

   https://doi.org/10.1111/1755-0998.12951  

   Jusino, Michelle A. ; Banik, Mark T. ; Palmer, Jonathan M. ; Wray, Amy K. ; Xiao, Lei ; Pelton, Emma ; Barber, Jesse R. ; Kawahara, Akito Y. ; Gratton, Claudio ; Peery, M. Zachariah ; et al ( January 2019 , Molecular Ecology Resources)

   DNA analysis of predator faeces using high‐throughput amplicon sequencing (HTS) enhances our understanding of predator–prey interactions. However, conclusions drawn from this technique are constrained by biases that occur in multiple steps of the HTS workflow. To better characterize insectivorous animal diets, we used DNA from a diverse set of arthropods to assess PCR biases of commonly used and novel primer pairs for the mitochondrial gene, cytochrome oxidase C subunit 1 (COI). We compared diversity recovered from HTS of bat guano samples using a commonly used primer pair “ZBJ” to results using the novel primer pair “ANML.” To parameterize our bioinformatics pipeline, we created an arthropod mock community consisting of single‐copy (cloned) COI sequences. To examine biases associated with both PCR and HTS, mock community members were combined in equimolar amounts both pre‐ and post‐PCR. We validated our system using guano from bats fed known diets and using composite samples of morphologically identified insects collected in pitfall traps. In PCR tests, the ANML primer pair amplified 58 of 59 arthropod taxa (98%), whereas ZBJ amplified 24–40 of 59 taxa (41%–68%). Furthermore, in an HTS comparison of field‐collected samples, the ANML primers detected nearly fourfold more arthropod taxa than the ZBJ primers. The additional arthropods detected include medically and economically relevant insect groups such as mosquitoes. Results revealed biases at both the PCR and sequencing levels, demonstrating the pitfalls associated with using HTS read numbers as proxies for abundance. The use of an arthropod mock community allowed for improved bioinformatics pipeline parameterization.

    

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2. The effect of shade tree species on bird communities in central Kenyan coffee farms

   Kammerichs-Berke, D ( October 2021 , Bird conservation international)

   Atkinson, Phil (Ed.)

   Shade coffee is a well-studied cultivation strategy that creates habitat for tropical birds while also maintaining agricultural yield. Although there is a general consensus that shade coffee is more “bird-friendly” than a sun coffee monoculture, little work has investigated the effects of specific shade tree species on insectivorous bird diversity. This study involved avian foraging observations, mist netting data, temperature loggers, and arthropod sampling to investigate bottom-up effects of two shade tree taxa - native Cordia sp. and introduced Grevillea robusta - on insectivorous bird communities in central Kenya. Results indicate that foliage-dwelling arthropod abundance, and the richness and overall abundance of foraging birds were all higher on Cordia than on Grevillea. Furthermore, multivariate analyses of the bird community indicate a significant difference in community composition between the canopies of the two tree species, though the communities of birds using the coffee understory under these shade trees were similar. In addition, both shade trees buffered temperatures in coffee, and temperatures under Cordia were marginally cooler than under Grevillea. These results suggest that native Cordia trees on East African shade coffee farms may be better at mitigating habitat loss and attracting insectivorous birds that could promote ecosystem services. Identifying differences in prey abundance and preferences in bird foraging behavior not only fills basic gaps in our understanding of the ecology of East African coffee farms, it also aids in developing region-specific information to optimize functional diversity, ecosystem services, and the conservation of birds in agricultural landscapes. 

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3. Abundance of spring‐ and winter‐active arthropods declines with warming

   https://doi.org/10.1002/ecs2.3473  

   Fitzgerald, Jacquelyn L. ; Stuble, Katharine L. ; Nichols, Lauren M. ; Diamond, Sarah E. ; Wentworth, Thomas R. ; Pelini, Shannon L. ; Gotelli, Nicholas J. ; Sanders, Nathan J. ; Dunn, Robert R. ; Penick, Clint A. ( April 2021 , Ecosphere)

   Because ectotherm activity and metabolism are sensitive to temperature, terrestrial arthropods may be especially responsive to ongoing climatic warming. Here, we quantified responses of arthropod abundance to two years of warming in an outdoor temperature manipulation experiment at Duke Forest, North Carolina, USA. Nine open‐top chambers were individually heated year‐round from 1.5° to 5.5°C above ambient temperature. From two years of monthly pitfall trapping, we collected and identified 4,468 arthropods representing 24 orders. We initially predicted that arthropods would experience the greatest negative effects of experimental warming during the summer months, when temperatures reach their yearly maximum and arthropods may be close to their maximum thermal tolerance limits. Instead, we found that the strongest negative effects on arthropod abundance occurred during the winter and spring, when ambient temperatures are relatively cooler, whereas the effects of experimental warming on abundance were not significant during the summer or fall. During the spring of 2012, the warmest spring on record for the southeastern USA, total arthropod abundance declined 20% per °C of experimental warming. Abundance declines were driven largely by flies (Diptera), which were the most abundant insect order, representing approximately a third of all arthropods collected. The most abundant arthropod family, Mycetophilidae (fungus gnats), declined 64% per °C of warming during the spring of 2012. Although previous research on climatic warming has focused on the impact of maximum yearly temperatures on organismal performance, our results are more consistent with the cool‐season sensitivity hypothesis, which posits that arthropods adapted for cooler conditions are likely to face the strongest negative effects of warming during the cooler seasons.

    

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4. New arthropod-Podostemaceae associations in Central and South America

   https://doi.org/10.3897/zookeys.1129.91398  

   Bethin, Jacob ; Krell, Rayda K. ; Philbrick, C. Thomas ( November 2022 , ZooKeys)

   Podostemaceae are a unique family of aquatic angiosperms found in river rapids and waterfalls throughout southern Asia, Africa, and the Americas. Podostemaceae are understudied, and consequently, the arthropods associated with these plants are not well known. We sought to expand knowledge of arthropod-Podostemaceae associations to better understand the impact of these plants on aquatic ecosystems and biodiversity. We examined samples of Podostemaceae collected between 1998 and 2007 from Brazil, Costa Rica, Suriname, and Venezuela for arthropods even though these samples were not collected with the intent to investigate arthropod-Podostemaceae associations. We examined 15 samples of Podostemaceae, including 10 species never evaluated for arthropod associations, and found over 9000 arthropods representing 12 different orders. The most abundant orders were Diptera (77.88%), Trichoptera (12.90%), Coleoptera (3.35%), and Lepidoptera (2.42%). We found several arthropods not previously reported from Podostemaceae, including Collembola and Acari, documented several instances of insects boring into plant tissues, and provide the first report of an insect-induced gall on Ceratolacis pedunculatum C.T. Philbrick, Novelo & Irgang. 

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5. Lianas maintain insectivorous bird abundance and diversity in a neotropical forest

   https://doi.org/10.1002/ecy.3176  

   Schnitzer, Stefan_A ; Michel, Nicole_L ; Powers, Jennifer_S ; Robinson, W_Douglas ( November 2020 , Ecology)

   The spatial habitat heterogeneity hypothesis posits that habitat complexity increases the abundance and diversity of species. In tropical forests, lianas add substantial habitat heterogeneity and complexity throughout the vertical forest profile, which may maintain animal abundance and diversity. The effects of lianas on tropical animal communities, however, remain poorly understood. We propose that lianas have a positive effect on animals by enhancing habitat complexity. Lianas may have a particularly strong influence on the forest bird community, providing nesting substrate, protection from predators, and nutrition (food). Understory insectivorous birds, which forage for insects that specialize on lianas, may particularly benefit. Alternatively, it is possible that lianas have a negative effect on forest birds by increasing predator abundances and providing arboreal predators with travel routes with easy access to bird nests. We tested the spatial habitat heterogeneity hypothesis on bird abundance and diversity by removing lianas, thus reducing forest complexity, using a large‐scale experimental approach in a lowland tropical forest in the Republic of Panama. We found that removing lianas decreased total bird abundance by 78.4% and diversity by 77.4% after 8 months, and by 40.0% and 51.7%, respectively, after 20 months. Insectivorous bird abundance and diversity 8 months after liana removal were 91.8% and 89.5% lower, respectively, indicating that lianas positively influence insectivorous birds. The effects of liana removal persisted longer for insectivorous birds than other birds, with 77.3% lower abundance and 76.2% lower diversity after 20 months. Liana removal also altered bird community composition, creating two distinct communities in the control and removal plots, with disproportionate effects on insectivores. Our findings demonstrate that lianas have a strong positive influence on the bird community, particularly for insectivorous birds in the forest understory. Lianas may maintain bird abundance and diversity by increasing habitat complexity, habitat heterogeneity, and resource availability.

    

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