The ecological role of mosquito larvae in aquatic environments

The ecological role of mosquito larvae in aquatic environments

The ecological role of mosquito larvae in aquatic environments

Assessing the community role and trophic interactions of Anopheles gambiae larvae in the Volta Region of Ghana.

IMAGE CREDIT: Michelle L. D’Souza

 The Anopheles gambiae mosquito complex, which consists of eight species, is the prevalent malaria vector in Sub-Saharan Africa1. While we have a reasonable understanding of predation rates, resource availability, and competition among aquatic invertebrate2-7, we lack a comprehensive appreciation of the larval ecology of An. gambiae, including their trophic role, diets, and population dynamics. My research aims to address this gap, crucial in integrating aquatic habitat management with vector control programs8.

With the advance of DNA technologies such as metabarcoding, we can now identify prey to a species level by examining the stomach contents of aquatic predators. When using these insights with network analyses, it is possible to quantify direct and indirect ecological interactions in the environment9. I will take advantage of these techniques for my research which aims to assess the trophic interactions of An. gambiae larvae in water bodies within two agricultural communities in Ghana.

I will collect mosquito larvae with a dipper, and a larger subset of invertebrates with an aquatic net (with a mesh size of 250 μm).  Each specimen’s gut contents will be analyzed using DNA barcoding and this data will be used to gain an understanding of the larval niche and ultimately An. gambiae’s role within the aquatic community. I will examine network interaction metrics such as connectance (the number of realized connections between species relative to what is available), degree (the number of interaction partners), betweenness (the importance of a species as a connector between different groups), and closeness (how central a focal species is in the community) to aid in niche construction. Temperature, pH, dissolved oxygen, salinity, and conductivity of the target water bodies will also be measured while sampling as these factors affect the occurrence and abundance of larvae by influencing the breeding behaviours of mosquitoes10.

In addition, I plan to study how different species of mosquito larvae compete for key resources. In the laboratory, the densities of local-caught larval populations of An. gambiae and other mosquito species will be manipulated to help determine the strongest competitor. While maintaining optimal rearing conditions by measuring the physio-chemical properties of the water daily, I will examine four indicators of overall growth and survival (the mean time to pupation, percentage of larvae that did not reach the adult stage, sex ratio, and mean female wing length) and therefore infer competitive strength among species. These data will provide important insights into predicting whether another mosquito species would dominate if the number of An. gambiae is reduced in the habitat.

An. gambiae is relatively small, constituting about half to one-third the mass of many Aedes mosquito species12. Foraging theory indicates that small, mobile insects of low profitability, do not form a preferred food source to predators unless they are massively clustered13. Though many species feed on mosquitos, these animals also feed on other small organisms that typically co-occur with An. gambiae14. For these reasons, I do not foresee that An. gambiae larvae will be a key food source for any predator in the aquatic environments in Ghana or that they will have a central role in local trophic systems.

If this is proven to be true, it will provide evidence that malaria-intervention methods that aim to suppress or reduce An. gambiae mosquitoes will not have detrimental consequences for the larger community.

Written by

Afia S. Karikari

Afia S. Karikari

African Regional Postgraduate Programme in Insect Science, University of Ghana, Accra, Ghana  

April 21, 2021

doi:10.21083/ibol.v11i1.6619 

This research is part of a larger effort by Target Malaria in Ghana to understand the role of the An. gambiae mosquito in the broader ecosystem.

For more information see:

The important interactions behind the itch

References:

  1. Service MW (1971) Studies on sampling larval populations of the Anopheles gambiae Bulletin of the World Health Organization 45:169–180.
  2. Service MW (1973) Mortalities of the larvae of the Anopheles gambiae Giles complex and detection of predators by the precipitin test. Bulletin of Entomological Research 62:359– 369.
  3. Service MW (1977) Mortalities of the immature stages of species of the Anopheles gambiae complex in Kenya: comparison between rice fields and temporary pools, identification of predators, and effects of insecticidal spraying. Journal of Medical Entomology 13:535–545.
  4. Ho BC, Ewert A, Chew LM (1989) Interspecific competition among Aedes Aegypti, albopictus and Ae. triseriatus (Diptera: Culicidae). Journal of Medical Entomology. 26:615–623.
  5. Barrera L (1996) Competition and resistance to starvation in larvae of container-inhabiting Aedes mosquitos. Ecological Entomology 21:117–127.
  6. Juliano SA, Lounibos LP and O’Meara GF (2004) A field test for competitive effects of Aedes albopictus on aegypti in south Florida: differences between sites and co-existence and exclusion? Oecologia. 139:583–593.
  7. Braks MAH, Honόrio NA, Lounibos LP, Lourenςo-de-Oliveira R, Juliano SA (2004) Interspecific competition between two invasive species of container mosquitos, Aedes aegypti and Aedes albopictus (Diptera: Culicidae), in Brazil. Annual Entomological Society of America 97:130–139.
  8. Li L, Bian L, Yakob L, Zhou U, Yan G (2009) Temporal and spatial stability of Anopheles gambiaelarval habitat distribution in western Kenya highlands. International Journal of Health Geographics. 8(70). doi:10.1186/1476-072X-8-70
  9. Fath BD, Patten BC (1998) Network synergism: emergence of positive relations in ecological systems. Ecological Modelling 107:127–143.
  10. Clements AN (1992) The Biology of Mosquitoes (Vol 1) Development, Nutrition and Reproduction. Chapman and Hall, London.
  11. Paajimans KP, Huijben S, Githeko AK, Takken W (2009) Competitive interactions between larvae of the malaria mosquitos, Anopheles arabiensis and Anopheles gambiae under semi-field conditions in western Kenya. Acta Tropica. 109:124–
  12. Koella JC, Lyimo EO (1996) Variability in the relationship between weight and wing length of Anopheles gambiae (Diptera: Culicidae). Journal of Medical Entomology 33: 261–264.
  13. Stephens DW, Brown JS, Ydenberg RC (2007) Foraging: Behavior and Ecology. University of Chicago Press, Chicago, IL.
  14. Findley JS, Black H (1983) Morphological and dietary structuring of a Zambian insectivorous bat community. Ecology 64:625–630.

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Ecological and epidemiological insights from blood meals

Ecological and epidemiological insights from blood meals

Ecological and epidemiological insights from blood meals

Using interaction networks to explore the community structure and network ecology of biting insects and their hosts
PHOTO CREDIT: Ben Bellekom, IMAGE CREDIT: Michelle L. D’Souza

Knowledge of variations in insect biting behaviour and feeding patterns of insect disease vectors is important in understanding disease epidemiology and establishing effective control methods. Blood feeding insects are embedded within complex ecological communities and interact with other species acting as predator, prey, or competitor. These interactions are likely to impact the population dynamics of those co-occurring species1.

Biting insects exist within a variety of landscapes, where landscape change is likely to influence host-insect interactions2,3.  For example, deforestation within the Peruvian Amazon resulted in 278 times more human interactions with the malaria vector Anopheles darlingi than in undisturbed habitat, leading to a rise in malaria transmission4. Consequently, creating vector controls requires an understanding of how the landscape modifies biting insect community structure and biting interaction frequencies. Similarly, community structure, host availability, and the frequency of interactions may all be affected by time, again with consequences for disease transmission.  For example, the Leishmaniasis vector, sand flies, are most active at dawn and dusk, with a resultant increase in transmission risk to nocturnal hosts5.

Biting insect research has primarily focused on the analysis of single biting insect species or small sets of interacting species to examine host usage and to screen vectors for pathogens of interest (such as Zika virus and malaria). As many biting insects are medically important, research has also focused on the effects of specific control initiatives, such as examining Anopheles mosquito abundances following the implementation of long-lasting insecticidal nets. Whilst limited work has examined the effect of habitat modification and temporal variations on feeding patterns and species abundances, this work has broadly overlooked the community aspect6. Therefore, there is currently an incomplete understanding of the degree to which these variations and distance from human habitation7, impact interaction frequencies, and the structural properties of the wider biting insect-host community. Indeed, as insect communities themselves are rarely studied, the full ecological and epidemiological implications of their interactions is currently unknown, so that the design of control strategies is potentially compromised.

Understanding such interactions is possible by constructing interaction networks, which provide a visual and mathematical representation of a community of species, connected through their feeding interactions8,9. I will create biting insect-host interaction networks using data from insect bloodmeals, focusing on the communities of biting flies in Ghana. I will explore the impact of landscape, comparing distinct habitat categories (such as scrubland and fallow land), and temporal variations (day or night), and the effect of proximity to human habitation on biting insect-host community composition, structural properties, such as how specialised the network is, and relative species’ abundances. I will use metabarcoding to create data on species interactions as it allows for the identification of animal DNA in a mixed sample collected from biting insect bloodmeals10.

I have augmented this fieldwork with a literature-based analysis of published blood meal interaction data. This provides an in-depth opinion on the value of interaction networks in understanding host-insect-disease interactions and highlights their future applications in identifying and monitoring emerging diseases and unrecognized vectors11. Further, using a global data set extracted from the literature, I aim to examine structural variations of biting insect-host communities between distinct habitat types and latitudes. The results generated by my work will provide valuable insight into biting insect community ecology, evaluate the potential impact of interventions on community structure and interactions.

Written by

Ben Bellekom

Ben Bellekom

Department of Zoology, University of Oxford, Oxford, UK

February 24, 2021

doi:10.21083/ibol.v11i1.6539

This research is part of a larger effort by Target Malaria in Ghana to understand the role of the An. gambiae mosquito in the broader ecosystem.

For more information see:

The important interactions behind the itch

References:

1. Ferguson HM, Dornhaus A, Beeche A, Borgemeister C, Gottlieb M, Mulla MS, Gimnig J, Fish D, Kileen G (2010) Ecology: A prerequisite for malaria elimination and eradication. PLOS Medicine 7. doi:10.1371/journal.pmed.1000303

2. Wolinska J, King KC (2009) Environment can alter selection in host-parasite interactions. Trends in Parasitology 25: 236–244. doi:10.1016/j.pt.2009.02.004

3. Lachish S, Knowles S, Alves R, Sepil I, Davies A, Lee S, Wood M, Sheldon B (2013) Spatial determinants of infection risk in a multi-species avian malaria system. Ecography 36:587–598. doi:10.1111/j.1600-0587.2012.07801.x

4. Vittor AY, Gilman RH, Tielsch J, Glass G, Shields T, Lozano WS, Pinedo-Cancino V, Patz J (2006) The effect of deforestation on the human-biting rate of Anopheles darlingi, the primary vector of falciparum malaria in the Peruvian Amazon. American Journal of Tropical Medicine and Hygiene 74:3–11. doi:10.4269/ajtmh.2006.74.3

5. Aklilu E, Gebresilassie A, Yared S, Kindu M, Tekie H, Balkew M, Warburg A, Hailu A, Gebre-Michael T (2017) Comparative study on the nocturnal activity of phlebotomine sand flies in a highland and lowland foci of visceral leishmaniasis in north-western Ethiopia with special reference to Phlebotomus orientalis. Parasites & Vectors 10:393. doi:0.1186/s13071-017-2339-6

6. Braack L, Almeida P, Cornel A, Swanepoel R, de Jager C (2018) Mosquito-borne arboviruses of African origin: review of key viruses and vectors. Parasites & Vectors 11:29. doi:10.1186/s13071-017-2559-9

7. Orsborne, J, Furuya-Kanamori L, Jeffries C, Kristan M, Mohammed A, Afrane Y, O’Reilly K, Massad E, Drakeley C, Walker T, Yakob L (2019) Investigating the blood-host plasticity and dispersal of Anopheles coluzzii using a novel field-based methodology. Parasites & Vectors 12:143. doi:10.1186/s13071-019-3401-3

8. Kaiser-Bunbury C.N, Blüthgen N (2015) Integrating network ecology with applied conservation: a synthesis and guide to implementation. AoB Plants 7. doi:10.1093/aobpla/plv076

9. Proulx S.R, Promislow D, Phillips P (2005) Network thinking in ecology and evolution, Trends in Ecology & Evolution 20:345–353. https://doi.org/10.1016/j.tree.2005.04.004

10. Drinkwater R, Schnell I, Bohmann K, Bernard H, Veron G, Clare E, Gilbert T, Rossiter S (2019) Using metabarcoding to compare the suitability of two blood‐feeding leech species for sampling mammalian diversity in North Borneo, Molecular Ecology Resources 19:105–117. doi:10.1111/1755-0998.12943

11. Bellekom B, Hackett TD, Lewis OT (2021) A network perspective on the vectoring of human disease. Trends in Parasitology. doi: 10.1016/j.pt.2020.12.001

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30 million reasons you will be missed

30 million reasons you will be missed

30 million reasons you will be missed

Pioneer field biologist, entomologist, and mentor, Terry Erwin passes away at age 79
Erwin supervising the trees at work, the Tiputini Research Station, Ecuador, 2013. PHOTO CREDIT: Beulah Garner

The world lost a brilliant mind last week when Terry L. Erwin passed away on May 11, 2020, at the age of 79. Many among us in the scientific community feel this great loss, for you did not need to have personally known, or even have met Erwin to recognize the name or appreciate the significance of his work.

    Erwin not only published prolifically on beetle systematics – describing four tribes, 22 genera, and 439 species of Carabidae – but also tremendously influenced the way many think about biodiversity.

    “He brought alive for many the far-off world and the mysteries therein of the neotropics,” said Beulah Garner, Senior Curator at the Natural History Museum in London, and Erwin’s colleague and friend of nine years. “I think it was the first time anyone, through their scientific exploration, had made a place and a fauna at once seem magical, touchable, and quantifiable.”

    Erwin was serving as a research entomologist and curator of Coleoptera at the Smithsonian Institution’s National Museum of Natural History at the time of his death. He was a pioneer in neotropical conservation biology and canopy research, having developed the study of tree canopy insects into an academic discipline as early as 1974.

    Notably, in his small paper in 1982 that examined canopy beetles and host plant relationships to understand the number of species present in an acre of Panamanian forest, Erwin dramatically expanded our conception of terrestrial insect diversity.

    Graphical abstract of Erwin’s 1982 paper IMAGE CREDIT: Michelle Lynn D’Souza

    As a young graduate student interested in using DNA barcoding to evaluate insect diversity in Central America and to assess global diversity estimates, Erwin’s work was a guidepost for my own research. His 1982 publication was particularly iconic. Ironically, it was in the last ‘throwaway’ paragraph (as he described it) – suggesting the presence of 30 million arthropod species, at the time estimated to be around one-and-a half million – that he sparked a global debate about the number of species on the planet.

    Even years later, he was enduring in his defense of the ‘30 million’ estimate, according to Garner. His holistic approach to field biology, with Carabidae at its core, enabled him to understand the relatedness of species as well as the mechanisms that drive such incredible diversity so clearly. “Even higher [than 30 million] he would say! And, having been in the field with him, with his meticulous observations of the microverse, his pioneering investigations into the forest canopy, I absolutely believe him,” said Garner. “These were not assumptions from a dataset, a modelling outcome, these were from direct in-field observations: a true naturalist.” While his estimate has been debated, refuted, and revised to approximately seven million arthropod species, the discussion remains active today.

    A true naturalist at home in the jungles of Yasuni National Park, Ecuador, 2018.
    PHOTO CREDIT: Beulah Garner

    While always having been interested in DNA-based techniques, it was not until much later in Erwin’s career that he used it in his own work. Heavily involved in the field of systematics, he was among the first of those in the early 1980s that experienced its infusion with the beginnings of gene sequencing. While in its own right revolutionary, sequencing technology was just another tool to study the natural world, one that would eventually be replaced by the tricorder, Erwin explained to Dr. Bilgenur Baloglu, then a Ph.D. student at the National University of Singapore studying chironomid diversity, in an interview during the International Congress of Entomology in Florida in 2016. He was referring to DNA barcoding and the beginnings of Drs. Paul Hebert and Dan Janzen’s tests with Costa Rican moths.

    As noted by Dr. Scott Miller, science committee member of the International Barcode of Life Consortium (iBOL) and deputy undersecretary at the Smithsonian Institution, Erwin was always enthusiastic about collaborations between iBOL and the Smithsonian to barcode insect genera, such as that currently funded by the Global Genome Initiative (GGI). He is the main reason that Carabid beetles were one of the first families covered under the project, contributing substantially to the species barcoded and deposited on the Barcode of Life Data Systems (BOLD), according to Miller. He also collaborated with Dr. Carlos Garcia-Robledo and others at the Smithsonian on a series of papers on insect-host plant relationships, among many others, that used DNA barcoding to identify the gut contents of insect herbivores as well as egg and larval plant associations to reconstruct species interactions in tropical networks.

    Miller first began working with Erwin in 1986 at the Smithsonian Institution as a postdoctoral fellow. Together they had a vision that became the Biodiversity in Latin America Tropics (BIOLAT), a program based around standardized sampling, something that may seem logical now, but was novel in fields like entomology at the time, according to Miller. Since then, a lot of other organizations have tried similar standardized programs but have struggled under the weight of the taxonomic impediment.  “When seen against this background, iBOL initiatives such as the Global Malaise Program or BioAlfa are truly amazing,” said Miller. “It is most unfortunate that DNA barcoding was not available when Terry started canopy fogging!”

    Erwin canopy fogging at 4 a.m. at the Onkone Gare camp, Yasuni National Park, Ecuador, 2018.
    PHOTO CREDIT: Beulah Garner

    From planning BIOLAT, to consulting for Biosphere 2 (the subject of the documentary ‘Spaceship Earth’), to the initial canopy fogging endeavour in Papua New Guinea (PNG) that eventually led to the Binatang Research Center and the PNG insect ecology program, Erwin encouraged, guided, and inspired Miller’s endeavours for years.

    Terry understood the importance of nurturing the next generation of talent, and especially the importance of diversifying the [scientific] pipeline.

    Dr. Scott Miller

    Science committee member of the International Barcode of Life Consortium (iBOL) and deputy undersecretary at the Smithsonian Institution

    “Terry understood the importance of nurturing the next generation of talent, and especially the importance of diversifying the [scientific] pipeline,” says Miller. “Terry was always eager to provide opportunities for young scientists, especially women, and people from developing countries.” While working together at the Smithsonian, Miller recounts how Erwin always hosted interns and fellows, bringing them to meetings and conferences, and trying to connect them to future opportunities.

    Erwin had the greatest spirit of academic generosity, quick to provide advice, a reference from his encyclopedic library, or specimens for one’s own research, according to Garner. Erwin nurtured a passion for discovery in many students and inspired it in even more biologists. As he told Bilgenur back in 2016, you do not become a biologist if you are out for money, but you do it for the joy of being out in the field. “For me, the bottom line is if you like fieldwork, be a biologist. It’s the best place to be,” said Erwin in her interview. “If you are out in the rainforest, every single day, actually maybe every hour, there’s a tremendous discovery. And that’s what’s really rewarding – discovery.”

    Erwin hunting Carabidae near the Tiputini Research Station, Ecuador, 2013.
    PHOTO CREDIT: Beulah Garner

    In the field, Garner recounts, Erwin would wake early, sit by the Tiputini river with black coffee and binoculars, and study the jungle whilst it woke. “Canopy fogging is a race to finish before the dawn and Terry was indefatigable,” said Garner. “It’s 4 a.m. in the primary jungles of South America, you’re setting up your traps, and Terry is right beside you, overseeing operations as if the rainforest were his orchestra and he the conductor.” In the evening after supper with head torch and aspirator, it would be time to go on a Carabidae hunt.

    It’s 4 a.m. in the primary jungles of South America, you’re setting up your traps, and Terry is right beside you, overseeing operations, as if the rainforest were his orchestra and he the conductor.

    Beulah Garner

    Senior Curator at the Natural History Museum, London

    He was fearless, saving Garner from a pack of marauding peccaries in Ecuador, as well as rescuing her from bivouacking army ants as they surrounded their camp in the dead of night. “He was and is the reason I endeavour to be a good field biologist,” said Garner. “His compassion and consideration and genuine every-day awe for the natural world is a method to live and work by.”

    Beulah Garner (left) and Terry Erwin (right) inspecting the flight intercept traps, Tiputini Research Station, Ecuador, 2013. PHOTO CREDIT: Dr. Kelly Swing

    Erwin very much valued the natural world, possessing an astute understanding of it that unfortunately, he takes with him. He feared having species reduced to just a sequence and believed that the rich natural history and the awe that the living world inspires in us needed to be accounted for as well, sentiments that led him to catalyze the Encyclopedia of Life (EOL) in 2004, according to Nana Naisbitt, EOL co-catalyst, founder of Chalkboard, and Erwin’s dear friend of 22 years. The EOL makes knowledge about life on Earth globally accessible and has had a long-standing collaboration with BOLD.

    As Naisbitt explained, Erwin was a profound mentor, one who changed the course of her life and the lives of many others through her work and her connection to him. He effectively snowballed Naisbitt’s career as a science champion, instrumental in her founding the Pinhead Institute, a science education non-profit and Smithsonian Affiliate. He was also key to many community outreach and mentorship programs while she worked as Executive Director of the Telluride Science Research Center, a job she got because of her work as the director of Pinhead. “It’s just impossible to say how many people he impacted,” said Naisbitt. “Terry liked to say that he plants seeds – ideas in students – and watches them grow. He planted countless seeds that grew strong and bright.”

    In Naisbitt’s assessment, Erwin was able to help so many people flourish because he possessed a phenomenal gift in the way he supported them and gave them confidence without being intrusive. “He connected me to the right people, then showed up for and supported me. Most times he would just sit there quietly in meetings and let me do the talking,” said Naisbitt. “His reputation and presence were enough – it conveyed the message, ‘I anoint this person’. In that way, he was so unbelievably respectful.”

    Naisbitt said that she had the impression Erwin believed he stood on the shoulders of giants. She described to me this image she had of him, of someone reaching down and pulling up younger scientists to stand on his shoulders. “And he did that so well. He did it over and over again, with immense generosity and without ego. And that is so rare.”

    His reputation and presence were enough – it conveyed the message, ‘I anoint this person’. In that way, he was so unbelievably respectful.

    Nana Naisbitt

    Founder of Chalkboard

    When Dr. Marlin Rice, back in a 2015 interview, asked Erwin how he would like others to remember him, his answer was simple – by what his students do. The influence a mentor has on their students and them on theirs, he described, is an unbroken chain that keeps connecting generations of thinkers. Erwin told Rice, “There’s this chain all the way from the great old-timers down through George [Ball – his Ph.D. mentor] and his students and what I’d like to do is to keep that chain going.”

    Indeed, Erwin’s brilliance, passion, and dedication for science extended those chains far beyond his students and colleagues, to countless others across space, like me. As the value of his research will certainly endure, those chains will also extend across time. Erwin was undoubtedly one of the rare ones among us whose influence has had, and will continue to have, an extraordinary reach.

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    Judge a caterpillar by what they eat, not where they’re found

    Judge a caterpillar by what they eat, not where they’re found

    Judge a caterpillar by what they eat, not where they’re found

    Gut content analysis of Peruvian caterpillars reveals new insights into host-plant relationships and the methods used to examine species interactions key to BIOSCAN

    The original primary rainforest surrounding Panguana station, Peru, Dept Huánuco, western Amazonia.

    PHOTO CREDIT: K. Wothe

    Understanding species and their associations with each other and with the environment – a key aspect of synecological research – is of great importance. For example, data on insect-host plant relationships can aid investigations into food webs and extrapolations of global species numbers as well as inform forestry, agriculture, and conservation practices.

    Supported by the Bavarian Ministry of Science (‘SNSB-Innovativ’), our recent pilot study examined the gut contents of Peruvian caterpillars demonstrating the potential for gathering large-scale data on species interactions when applying DNA barcoding and high-throughput sequencing technologies. We obtained 130 caterpillars (moth larvae) by canopy fogging at the Panguana research station, an area of tropical primary forest in western Amazonia. DNA barcode analysis resulted in 119 successfully sequenced larvae, more than half of which matched with moth reference sequences on BOLD. Surprisingly high biodiversity was uncovered from our modest sample – 92 BINs or species proxies. The trees from which caterpillars were collected were also identified, both by morphology and DNA barcoding.

    Panguana research station, Peru, Dept Huánuco, western Amazonia, with the characteristic Lupuna tree (Ceiba pentandra, Malvaceae) in the background.

    PHOTO CREDIT: J. Diller

    Knowing the tree and larva identity is not enough to conclude a host-plant relationship, particularly in a dense tropical rainforest. Caterpillars may in fact be feeding on the epiphytes, lianas, lichens, algae, fungi, or mosses associated with trees (i.e., alternative feeding), and sometimes larvae may have been fogged down from neighbouring trees. To confirm a direct insect-host plant relationship, we partnered with the company Advanced Identification Methods (AIM) to design a high-throughput sequencing (HTS) protocol with plant markers (rbcL, psbA) that would enable the identification of plant matter from the gut contents of ten larvae. Results revealed only two matches between the fogged tree and larval gut content which suggests a rather high percentage of alternative feeding. In three cases, the gut content clearly indicated feeding on lianas and neighbouring trees. Interestingly, the analysis of four larvae resulted in the putative presence of Bryophyta, suggesting moss-feeding in Lepidoptera, a phenomenon rarely observed. Potential contamination (for example, through the diffusion of plant DNA into the alcohol of the bulk sample) has yet to be ruled out, work which is currently being validated in a subsequent project investigating the gut contents of an additional 190 larvae.

    Automeris denticulata (Conte, 1906) (Saturniidae): Larva (left), selected from canopy fogging bulk samples of a Poulsenia (Moraceae) tree at the Panguana station, identified by its COI barcode; Adult (right), collected at the Panguana station.

    PHOTO CREDIT: Mei-Yu Chen & Dr. R. Mörtter

    Our approach of combined canopy fogging, DNA-based identification, and gut content analysis resulted in two key findings. First, a significant portion of both insect and plant taxa can be identified even in highly diverse, tropical regions – more than 97% to a family level and about 80% to a species or genus level. Secondly, we can successfully confirm or reject the hypothesis that caterpillars feed on the trees where they are collected by identifying their diets through an HTS protocol on gut contents. Importantly, the taxonomic resolution of animal and plant identifications will increase with further investments into DNA reference libraries. We recommend specimen de-contamination (e.g. by bleaching) and/or isolated storage of the target taxa rather than bulk storage to improve the reliability of gut content analysis.

    Urania leilus (Linnaeus, 1758) (Uraniidae): Larva (left), selected from canopy fogging bulk samples of an Oxandra polyantha (Annonaceae) tree at the Panguana station, identified by its COI barcode; Adult (right).

    PHOTO CREDIT: Mei-Yu Chen & Dr. J. Diller

    The techniques employed in our pilot have immense potential for unveiling trophic interactions in tropical regions at a very large scale as they are fast and cost-effective. The latter is enabled, in part, by the availability of target specimens in the by-catch of other studies. For example, our efforts fogging 150 trees in a separate project assessing the biodiversity of ants have resulted in 1,200 lepidopteran larvae. Subsequent aspects of the workflow, from selecting the larvae from bulk samples, tissue sampling, photography, and databasing, required 10–20 minutes per larva and can be performed with relatively low expertise. The costs for subsequent lab work, i.e. identification of larvae and their gut contents, currently amount to 20–25 € per larva and these costs will soon drop considerably. In contrast, traditional approaches involving the searching and rearing of larvae, and the identification of hatched adults by experts is massively time and resource consuming.

    Providing reliable data on trophic interactions is one of the major goals of the BIOSCAN program, one that will be a powerful tool for investigating food webs, for determining the amplitude of alternative or multiple feeding sources, and for the study of phagism (monophagy versus polyphagy), thus gaining data for extrapolations of global species numbers. These data will also be particularly important for pest management in forestry, and agriculture, and for conservation purposes.

    Overcoming the current lack of knowledge is a major challenge, particularly in ecoregions with megadiverse faunas and floras. Yet, its success is imperative for humanity considering the unprecedented biodiversity losses we currently face. In this context, the recently launched BIOSCAN with its focus on revealing species interactions will embolden an important plan for the international research community to come together in understanding nature and conserving it for a sustainable future.

     

    Read the complete manuscript in PLoS ONE.

    Written by

    Axel Hausmann

    Axel Hausmann

    Juliane Diller

    Juliane Diller

    Amelie Höcherl

    Amelie Höcherl

    SNSB – Staatliche Naturwissenschaftliche Sammlungen Bayerns - Zoologische Staatssammlung München, Munich, Germany

    May 6, 2020
    https://doi.org/10.21083/ibol.v10i1.6133 

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    DNA BARCODING AND GENOMICS IN THE MEGADIVERSE AMAZON ALTITUDE FIELDS

    by Guilherme Oliveira, Gisele Nunes, Rafael Valadares, Ronnie Alves and Santelmo Vasconcelos | Apr 7, 2019

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    BIOSCAN: tracking biodiversity on Earth

    BIOSCAN: tracking biodiversity on Earth

    BIOSCAN: tracking biodiversity on Earth

    iBOL’s new seven-year, $180 million global research program that aims to revolutionize our understanding of biodiversity and our capacity to manage it.
    January 20, 2019 By the International Barcode of Life Consoritum – ibol.org

    BIOSCAN is iBOL’s new seven-year, $180 million global research program that aims to revolutionize our understanding of biodiversity and our capacity to manage it. Involving scientists, research organizations, and citizens, BIOSCAN will explore three major research themes: Species Discovery, Species Interactions, Species Dynamics.

    iBOL (International Barcode of Life Consortium) involves researchers in 30+ nations who share a mission to transform biodiversity science through DNA-based approaches with DNA barcoding at its core. iBOL works in partnership with academic, government, and private sector organizations.

    For more information on BIOSCAN and iBOL visit: ibol.org

    Additional video footage provided by:

    Centre for Biodiversity Genomics, University of Guelph, Canada
    Hakai Institute, Canada

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    HOW A TROPICAL COUNTRY CAN DNA BARCODE ITSELF

    by Dan Janzen and Winnie Hallwachs | Oct 2, 2019

    comment on this article

    The Barcode Bulletin moderates comments to promote an informed and courteous conversation. Abusive, profane, self-promotional, or incoherent comments will be rejected.