Dr hab. Agnieszka Soszyńska-Maj from the Department of Invertebrate Zoology and Hydrobiology has been studying insect inclusions in amber dating back even 100 million years. The subject of research are mecopterans, an evolutionary old group of insects. About 800 species classified into 9 families live in the world nowadays, and almost 350 extinct species are known from palaeontological discoveries. Most of the mecopterans species live in the moderate or subtropical climate zones. There are 21 species found in Europe, including 10 in Poland. These insects most commonly live in humid environments, among thickets, trees and bushes.
Mecopterans, are a row of insects with very interesting mating habits. The research I am conducting concerns the diversity of male mecopterans in the Mesozoic and Eocene. So far, scientists' research has focused on discovering new species, and I have made an interpretation of their mating habits based on their body structure.
– explains prof. Agnieszka Soszyńska-Maj.
Mecopterans – violence and wedding gifts
Mecopterans have very interesting mating behaviour. There is no other group of insects that would be so diverse in this respect. Males have a very wide range of sexual behaviours, they can, for example, force females to reproduce. They use a special body part to do this, namely the scorpion-like tail (appendix on the abdomen of various lengths).
This organ is used to capture and immobilize female's wings to force her into copulating. This is the most oppressive way to reproduce but there are also gentler strategies, where a male does not coerce but offers a female a "wedding gift." Most often it is just food, a male offers food to a female and the copulation takes place while she is busy eating the "gift".
– explains prof. Soszyńska-Maj.
On the other hand, the mildest form that occurs with some mecopterans nowadays is the method used by males which have highly developed salivary glands, thanks to which they can produce large amounts of nutritional secretion. Of course, it is used to feed the female during the mating which may last up to several hours.
Research on Baltic amber shows that 40 million years ago even more oppressive "methods of seduction" were present. The structure of insects from that period indicates not only that the females could not break free during copulation, but they could also suffer body injuries. At that time, the scorpion-like tail was built of two very long appendages acting like tongs armed with bristles. These behaviours appeared in the Eocene but thanks to our research we also know that this strategy did not survive, since such behaviours are no longer observed.
– explains prof. Soszyńska-Maj.
Burma, Spain, the Baltic Sea
The studied amber comes from 100 million years ago, i.e. from the Cretaceous period, when dinosaurs still existed. It is mined in Burma and thanks to researchers from China, scientists from Lodz have access to it. In turn, the oldest known mecopterans inclusion in the fossil resin in the world comes from amber mined in Cantabria, Spain, which was tested in Lodz thanks to dr Ricardo Pérez-de la Fuente from the Museum of Natural History in Oxford. Scientists are also studying "much younger" specimens (40 million years old!) recovered from the Baltic region. Thanks to this variety of objects, it is possible to indicate how these insects, their structure, and thus their habits, changed over time.
The specimens trapped in amber are not only amazing, three-dimensional research objects. The insects we focus on have survived in the resin for hundreds or tens of millions of years. It is an amazing source of knowledge for researchers on times that are long gone. Fossil research is used to track evolution and thanks to that we can see how a given group has evolved. The climate on earth was completely different then, the continents were different, and the land was inhabited by completely different fauna.
– says prof. Soszyńska-Maj.
However, the research is not just about studying history. Adds Soszyńska-Maj:
We also learn a lot about how fauna has changed under the influence of climate change. On this basis, we can try to predict how such changes will unfold in the future. Observing climate change, we can design how it will affect the ecosystems that exist today.
Source: Faculty of Biology and Environmental Protection, University of Lodz