The first serious freezing of the year will kill the adult dragonflies.
Translated from Dutch Vroege Vogels radio:
Dragonflies on watercolors
Friday, December 1, 2017
At the end of the nineteenth century, the Belgian Baron Edmond de Sélys Longchamps drew and painted many hundreds of dragonflies. Not for fun, but for science.
An important and valuable collection. Still, the folders with dragonfly aquarelles fell into oblivion. But in 2002 they were found again, almost literally under a layer of dust in a cabinet at the Royal Belgian Institute of Natural Sciences in Brussels.
Since then the Dutch dragonfly researchers Karin Verspui and Marcel Wasscher have studied the drawings. ‘We are talking about a time when there was obviously no good photography yet. This kind of drawings and watercolors were the gold standard for describing species”, says Verspui. ‘There are very special examples, including many so-called holotype specimens. These are the original individuals used to describe a new species. Where most of the type specimens themselves have completely lost their color, these watercolors are still of exceptional quality. These drawings deserve a larger audience”, says Verspui.
The digitized watercolors can be found on the RBINS site.
Ms Verspui said today on radio that Baron Edmond de Sélys Longchamps was an amateur entomologist. Nevertheless, he wrote scientific descriptions of about 700 dragonfly and damselfly species; about a third of the 2000 species known to science then.
This video says about itself:
The Secret World of Dragonflies | Short Film Showcase
17 December 2014
The colorful, acrobatic dragonfly may seem familiar, but this stunning macro film reveals the mysteries behind its metamorphic life cycle—and some surprising adaptations.
See more from filmmaker Andy Holt here.
Learn about the making of this film here.
From the University of Turku in Finland:
What is on the menu for dragonflies
October 3, 2017
Researchers from the Universities of Turku and Helsinki, Finland, are the first in the world to discover which species adult dragonflies and damselflies prey upon, as modern laboratory techniques enabled the study of the insects’ diet. In the study, prey DNA was extracted from the tiny dragonfly droppings and the researchers managed to identify dozens of prey species from the samples. The results shed light on dragonflies’ position in natural food webs with an unprecedented specificity.
Dragonflies and damselflies, i.e. the odonates, are numerous and quite large insects. As adults, they control the air space as the apex predators of invertebrates. However, the diet of dragonflies has never been resolved comprehensively as it is difficult to observe them catching or eating their prey. Now for the first time, a research group led by Finnish scientists has established which insects the adult dragonflies prey on.
The dragonflies’ menu was studied by extracting and identifying the DNA of prey species from faecal samples. With this method, the researchers were able to identify in detail which insects the three studied dragonfly species had eaten and a large group of different prey species was identified as their prey. At the same time, the researchers discovered that the three dragonfly species prey upon practically the same species — and that they share their diet with birds and bats which are the dominant vertebrate predators.
The research group included researchers from the Biodiversity Unit of the University of Turku, the Department of Agricultural Sciences of the University of Helsinki, and Swedish University of Agricultural Sciences.
This study is very significant as dragonflies are at the top of the insect food webs all over the world and regulate the number of many other insect species. Therefore, it is important to know exactly which species they eat. From there, we can, for example, assess the dragonflies’ impact on the populations of those insects that are harmful to humans. Yet so far, the information on the diet of adult dragonflies has practically been based on individual visual observations of their prey, says Researcher and leader of the research group Kari Kaunisto from the Biodiversity Unit of the University of Turku.
In the study, the researchers also tested the applicability of different methods for extracting DNA, and their results can be utilised in future research.
When Kari told me of his idea, I was immediately interested. It was surprising that no one had done this before and I accepted the challenge at once. Often in research, earlier studies provide a starting point for laboratory work, but in this case we had to start from the beginning. In a new project, it’s a good idea to test different methods and we wanted to lay a good foundation for future studies, says researcher Eero Vesterinen from the University of Helsinki, who in his earlier research has specialised in the research of feeding biology, especially by applying molecular research methods based on DNA.
As dragonflies are large insects, they have long interested researchers as well as nature lovers. The number of the odonate species is relatively small and identifying different species is easier than with other insect groups. Dragonflies are excellent model species for biological research also because they give indications of the state of both terrestrial and aquatic environments. Dragonflies spend their larval phase in water, after which they control the air space as the flying apex predators of invertebrates. The new study sheds additional light on dragonflies‘ role in the aerial food web, notes Professor of Insect Ecology Tomas Roslin from the Swedish University of Agricultural Sciences, who also participated in the study.
The study was recently published in the international Ecology and Evolution journal.
This is a darter (Sympetrum) dragonfly, morning dew and sunrise video.
Harry Heuven in the Netherlands made this 31 August 2017 video.
This 17 August 2017 video is about a banded darter dragonfly cleaning itself.
Chris Ruijter in the Netherlands made this video.