Efficiency of insect biodiversity monitoring via Malaise trap samples and DNA barcoding

The massive decline of over 75% insect biomass reported from Germany between 1989 and 2013 by expert citizen scientists proves the urgent need for new methods and standards for fast and wide-scale biodiversity assessments. If we cannot understand species composition, as well as their diversity patterns and reasons behind them, we will fail not only to predict changes, but also to take timely and adequate measures before species go extinct.

An international team of scientists belonging to the largest and connected DNA barcoding initiatives (iBOL, GBOL, BFB), evaluated the use of DNA barcode analysis applied to large samples collected with Malaise traps as a method to rapidly assess the arthropod fauna at two sites in Germany between May and September.

One Malaise trap (tent-like structure designed to catch flying insects by attracting them to its walls and then funneling them into a collecting bottle) was set in Germany’s largest terrestrial protected natural reserve Nationalpark Bayerischer Wald in Bavaria. Located in southeast Germany, from a habitat perspective, the park is basically a natural forest. The second trap was set up in western Germany adjacent to the Middle River Rhine Valley, located some 485 kilometers away from the first location. Here, the vegetation is eradicated annually due to St. Martin’s fires, which occur every November. Their findings are published in the open access Biodiversity Data Journal.

DNA barcoding enables the identification of a collected specimen by comparing its BIN (Barcode Index Number) against the BOLD database. In contrast to evaluation using traditional morphological approaches, this method takes significantly less experience, time and effort, so that science can easily save up on decades of professional work.

However, having analyzed DNA barcodes for 37,274 specimens equal to 5,301 different BINs (i.e., species hypotheses), the entomologists managed to assign unambiguous species names to 35% of the BINs, which pointed to the biggest problem with DNA barcoding for large-scale insect inventories today, namely insufficient coverage of DNA barcodes for Diptera (flies and gnats) and Hymenoptera (bees and wasps) and allied groups. As the coverage of the reference database for butterflies and beetles is good, the authors showcase how efficient the workflow for the semi-automated identification of large sample sizes to species and genus level could be.

In conclusion, the scientists note that DNA barcoding approaches applied to large-scale samplings collected with Malaise traps could help in providing crucial knowledge of the insect biodiversity and its dynamics. They also invite their fellow entomologists to take part and help filling the gaps in the reference library. The authors also welcome taxonomic experts to make use of the unidentified specimens they collected in the study, but also point out that taxonomic decisions based on BIN membership need to be made within a comparative context, “ideally including morphological data and also additional, independent genetic markers”. Otherwise, the grounds for the decision have to be clearly indicated.

The study is conducted as part of the collaborative Global Malaise Trap Program (GMTP), which involves more than 30 international partners. The aim is to provide an overview of arthropod diversity by coupling the large-scale deployment of Malaise traps with the use of specimen-based DNA barcoding to assess species diversity.

Sequence analyses were partially defrayed by funding from the government of Canada through Genome Canada and the Ontario Genomics Institute in support of the International Barcode of Life project. The German Barcode of Life project (GBOL) is generously supported by a grant from the German Federal Ministry of Education and Research (FKZ 01LI1101 and 01LI1501) and the Barcoding Fauna Bavarica project (BFB) was supported by a 10-year grant from the Bavarian Ministry of Education, Culture, Research and Art.

 

 

Original source:

Geiger M, Moriniere J, Hausmann A, Haszprunar G, Wägele W, Hebert P, Rulik B (2016) Testing the Global Malaise Trap Program – How well does the current barcode reference library identify flying insects in Germany? Biodiversity Data Journal 4: e10671. https://doi.org/10.3897/BDJ.4.e10671

Underwater mushrooms: Curious lake fungi under every turned over stone

While fungi are well known for being essential in cycling carbon and nutrients, there are only about 100,000 described species in contrast to the 1.5 to 3 millions, assumed to exist on Earth. Of these, barely 3000 fungi belong to aquatic habitats. In fact, freshwater fungi have been researched so little, it is only now that an international research team provide the first lake-wide fungal diversity estimate in the open access journal MycoKeys.

Over the spring and the early summer of 2010, a large team of scientists, led by Dr Christian Wurzbacher and Dr Norman Warthmann, affiliated with the Leibniz-Institute of Freshwater Ecology and Inland Fisheries and the Berlin Center for Genomics in Biodiversity Research, Germany (currently at University of Gothenburg, Sweden, and the Australian National University, Australia, respectively), collected a total of 216 samples from 54 locations, encompassing eight different habitats within Lake Stechlin in North-East Germany.image-1

Having recovered samples on three occasions over the course of the study, their aim was to test how habitat specificity affects the fungal community and whether fungal groups would reflect the availability of particulate organic matter as substrate. Unlike previous studies of aquatic fungi that compared water samples among different lakes or seasons, theirs would compare the diversity among habitats within a single lake. This included the study of fungi living in the water and the sediments, as well as fungi living on the surfaces of plants and other animals.

As a result, the scientists concluded that every type of habitat, i.e. sediments, biofilms, and submerged macrophytes (large aquatic plants), has a specific fungal community that varies more than initially expected. Of these, lake biofilms, representing a group of microorganisms, whose cells stick to each other, and cling together to a surface, turned out to be the hotspots for aquatic fungi.

“Our study provides the first estimate of lake-wide fungal diversity and highlights the important contribution of habitat heterogeneity to overall diversity and community composition,” the scientists summarise. “Habitat diversity should be considered in any sampling strategy aiming to assess the fungal diversity of a water body.”

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Original source:

Wurzbacher C, Warthmann N, Bourne EC, Attermeyer K, Allgaier M, Powell JR, Detering H, Mbedi S, Grossart H-P, Monaghan MT (2016) High habitat-specificity in fungal communities in oligo-mesotrophic, temperate Lake Stechlin (North-East Germany). MycoKeys 16: 17-44. https://doi.org/10.3897/mycokeys.16.9646

Cost-benefit analysis of strategies against severely harmful giant hogweed in Germany

While invasive species are considered to be a primary driver of biodiversity loss across the globe, species such as the alien for Germany giant hogweed pose even greater risks, including health hazards to humans, limited accessibility to sites, trails and amenity areas, as well as ecological damages.

Since 1st January 2015, EU member states are obligated to develop concrete action plans against (further) spread of invasive alien species. In order to do so, however, policymakers need adequate knowledge about data of the current spread situation as well as information about costs and benefits of control measures. Therefore, German researchers analyse the present situation and control measures, as well as the cost-effectiveness of the possible eradication strategies. Their analysis is published in the open access journal NeoBiota.

Largely spread across Germany, the giant hogweed (H. mantegazzianum) grows in a wide range of habitats, including roadsides, grasslands, riparian habitats and woodland margins. The highest invasion percentage (18.5%) was found for abandoned grasslands, field and grassland margins, and tall-forb stands.

While the species poses a serious threat on native biodiversity through competitive displacement of native plants, it is particularly dangerous to human health. Its watery sap contains several chemical agents. In contact with the skin, this sap can cause severe blistering if the person is simultaneously exposed to sunlight. Furthermore, the hypersensitivity of the skin towards sunlight may persist for a number of years. Additionally, the giant hogweed can limit public accessibility to sites, trails and amenity areas, as well as inflict ecological damages, such as erosion at riverbanks.

In order to provide policymakers with the information needed for adequate control measures, Dr. Sandra Rajmis from the Julius Kühn-Institute, Dr. Jan Thiele from the University of Münster, and Prof. Dr. Rainer Marggraf from Georg-August-Universität Göttingen examine costs and benefits of controlling giant hogweed in Germany.

To address these challenges, the scientists firstly study the present state and costs of control measures, based on survey data received from German nature authorities. Then, they analyse the identified control options in terms of cost effectiveness with regard to the invaded area types and sizes in the infested German districts. To estimate the benefits of the eradication strategies, they turn to a choice experiment survey conducted in German households.

“Only in light of these findings, policymakers can properly understand about the societal costs and benefits of alternatives and decide about societal favored control options in Germany,” point out the researchers.

The team also notes that cost-effectiveness of eradication strategies depends on the length of the period over which they are implemented and observed.

“As this is the first cost-benefit analysis estimating welfare effects and societal importance of giant hogweed invasion control, it could serve as guideline for assessments of eradication control in other European countries and support the implementation of the EU directive 1143/2014,” they conclude.

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Original source: Rajmis S, Thiele J, Marggraf R (2016) A cost-benefit analysis of controlling giant hogweed (Heracleum mantegazzianum) in Germany using a choice experiment approach.NeoBiota 31: 19-41. doi: 10.3897/neobiota.31.8103