Have you noticed one of the unusual tent structures set up in Cae Trawscoed or the Double Walled Garden? They are in fact Malaise traps, which are tent-like intercept traps to catch flying insects. The Malaise trap was invented by Swedish entomologist René Malaise after realising that more insects were caught in his tent than in his netting. Insects hit the middle mesh wall, then fly upwards and are funnelled into the peak of the trap where they’re caught in an ethanol-filled bottle, which preserves the specimen. This surveying method has many different uses, including monitoring changes in seasonal abundance, and conducting site surveys for invertebrates. In fact, the technique of Malaise trapping is what alerted a group of German scientists to the plummeting insect numbers, as they recorded more than a 75% decrease in total flying insect biomass over a 27-year period in 63 nature protection areas in Germany. Here, we set up two Malaise traps each month throughout the year to collect insects as part of the BIOSCAN project, run by the Wellcome-Sanger Institute.
Here at the Science Centre, we are always trying to find new and innovative ways to learn more about the natural world. So when the Wellcome Sanger Institute approached us to take part in their new pilot study to test invertebrate survey techniques, we jumped at the chance!
The Wellcome Sanger Institute was founded to sequence the human genome, and is now a globally recognised research centre that undertakes large-scale genome science, and have sequenced the genomes of hundreds of species for the first time. Now they are taking part in a new global project called BIOSCAN, spearheaded the International Barcode of Life, which aims to “revolutionise our understanding of biodiversity and our capacity to manage it,” making it a very exciting project to be a part of!
Insects are of major ecological importance, providing many ecosystem services such as pollination, biological pest control and nutrient cycling. Insect populations are declining globally, with over 40% of species thought to be threatened with extinction, which is a major concern for human and ecosystem health. However, there is no global scientific monitoring of insect abundance, making it hard to accurately track insect dynamics and declines. In addition, there is estimated to be 5.5 million insect species, with 90% yet to be named. The vision of this new project is to use accessible DNA-based techniques to aid species discovery, learn more about species interactions and to examine biological communities. This will provide an effective monitoring system for terrestrial invertebrates across the globe, giving valuable information on their distribution and interactions, especially in a changing world.
The National Botanic Garden of Wales is one of ten sites in the UK selected to take part in this global project, and the only site in Wales! One trap is set up in the Double Walled Garden, and the other in Cae Trawscoed, in the same position each month for a period of 24 hours. After collection, we can begin identifying the specimens, and transferring them to a well plate, with each insect in its own well. As we are not expert entomologists, we do our best to identify each insect to order level. The Diptera (flies) are the easiest to identify as they have a pair of club-like halteres, which are modified hindwings that act as flight stabilisers. After each insect has been sorted into their own individual well (which can seem like an endless task in the height of summer, when there can be hundreds of insects to sort), the plates are sent to Sanger for processing.
Sanger will collect DNA from these samples and identify them using DNA metabarcoding techniques, which uses a short, standardised genetic region that acts as a ‘barcode’ to identify the species from a reference database. This method can be used instead of, or in addition to, the traditional method of visual identification using a microscope, which requires expert entomologists and a great deal of time. The DNA metabarcoding method of species identification is very familiar to the Science Team at the Garden, as researchers here have been using this technique to identify species of plants from pollen samples collected by bees and other pollinators to learn more about their use of floral resources. Using this technique to identify insects will allow the ascertainment of species composition of mass collections with greater taxonomic resolution, giving information on species diversity and distribution.
This ambitious project aims to metabarcode assemblages from 2,000 sites, and will involve the analysis of at least 100 million specimens, with millions of new species expected to be discovered. Here at the Garden we are lucky to be a part of BIOSCAN, laying the foundations for a global biosurveillance system that will track biotic change across the world!
References
BIOSCAN, International Barcode of Life, Available: https://ibol.org/programs/bioscan/
Hallmann et al. (2017) More than 75 percent decline over 27 years in total flying insect biomass in protected areas, PLoS ONE, Available: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185809&_ga=2.42103269.1751527880.1531267200-635596102.1531267200
van der Slujis (2020) Insect decline, an emerging global environmental risk, Current Opinion in Environmental Sustainability, Available: https://www.sciencedirect.com/science/article/pii/S1877343520300671
Sánchez-Bayo & Wyckhuysbcd (2019) Worldwide decline of the entomofauna: A review of its drivers, Biological Conservation, Available: https://www.sciencedirect.com/science/article/pii/S0006320718313636