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December 4, 2012
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Department of Life Sciences seminar

 

Insect diversity and pest control in the anthropogenic habitats of NE China

 

Jan Axmacher

Department of Geography, University College London

 

Friday 7 December 11:00
Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)

 

 

The natural environment of NE China has been altered by humans for thousands of years. Nonetheless, both intensity and spatial extend of these alterations have greatly increased since the middle of the last century. Agricultural production was greatly intensified, while the remaining natural forest cover was widely cleared. The severe environmental degradation which followed has led to an increased awareness of the importance of environmental issues in the last few decades, with re- and afforestation projects being currently established throughout China at an unprecedented scale. At the same time, agricultural practices following the maxim ‘the more, the better’ are also increasingly questioned, with the importance of biological pest control recognized as a potential cheap and less environmentally detrimental alternative to chemical pesticides.

 

Given these recent developments, I have started a number of collaborative research projects with the Chinese Agricultural University and the Institute of Botany, Chinese Academy of Sciences to investigate diversity and species composition of ground beetle assemblages in reforested habitats and the agricultural landscapes of the Hebei province, looking at both the diversity and potential pest control function of these mostly predatory beetles. Our research shows that the diversity of ground beetles varies strongly between different types of forest ecosystems, with naturally regenerating birch forests and open larch plantations showing a high abundance, but low diversity in carabids. Plantations of native oak and pine monocultures, as well as forests composed of a mixture of planted and naturally regenerating trees harbour distinctly higher diversity levels.

 

In the agricultural landscape, even very intensively managed double-cropping systems comprising of summer maize and winter wheat monocultures can support surprisingly high levels of ground beetle diversity, while cotton monocultures were found to harbour distinctly lower levels of carabid diversity. Landscape elements like the diversity of land-use types were found to have only a limited effect on the diversity of the ground beetle community at least in some of our study areas. A comparison of diversity patterns in ground beetles and geometrid moths finally showed that links between these highly diverse herbivore and insectivore taxa are highly complex, with distinctly different spatial patterns observed in these two families.

 

 

 

For additional details on attending this or other seminars see http://www.nhm.ac.uk/research-curation/seminars-events/index.html

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Thomas Simonsen has published an invited peer-reviewed paper in Arthropod Structure and Development in collaboration with co-workers from the Finnish Museum of Natural History and Naturalis (Dutch Museum of Natural History) on the continuing importance of morphology in Lepidoptera systematics.

 

Taxonomy and systematics are areas of science that are focused on description, naming, classification and evolutionary relationships of living things.  Such science is the fundamental reason for the existence of large natural history collections, and traditionally the focus has been on morphology - the use of combinations of physical characters such as number of legs, wing patterns or body form.  The differences in these characters between species can be compared and allow identification - so a fly will have one pair of wings but a bee will have two pairs, for example. Over time, different species and groups have diverged as a result of evolution and in general become progressively more different in form.

 

However, while morphology is a key tool in understanding diversity, evolutionary difference can be seen also in molecules, particularly DNA.  DNA of different species can be compared and the degree of difference used to assess patterns of evolution and relationships.  The use of DNA in taxonomy and systematics is of increasing importance and museum collections are of great value in this new science - a purpose never suspected by those who started to assemble them in the 18th and 19th Centuries.

 

Wallace birdwing NaturalHistoryMuseum_PictureLibrary_056153_IA.jpgOrnithoptera croesus, Wallace's golden birdwing butterfly - a member of the Paplionidae family

 

Some scientists have argued that DNA alone will be used in future to assess diversity and to identify species: it is after all DNA differences that are the root cause of morphological difference - so why use both?  There are in fact a number of reasons why morphological techniques will be of continuing importance - Thomas and colleagues explore the relative value of morphology and molecular information for large groups of butterflies in this paper.

 

They reviewed the morphological characters that are important for understanding butterfly phylogeny and evolution in the context of large-scale molecular phylogenies (evolutionary classifications) of the group. In particular, they were interested in what the molecular evidence was able to tell them about the evolution of morphological features - so for example, were characters that are used to separate distantly related groups actually caused by large genetic differences?

 

They looked in particular at the families Papilionidae, Nymphalidae and Hesperiidae which have all been studied with a combination of morphological and molecular data in recent years. What they found was that a  scientifically more valuable classification emerged not from using either molecular or morphological techniques, but from using both in combination. They argue that morphology still has an immensely important role to play in butterfly (and insect) phylogenetics - including its value in understanding how the whole organism is important in evolutionary changes, natural selection and diversity.  

 

Simonsen, T. J., de Jong, R., Heikkilä, M. & Kaila, L. (2012). Butterfly morphology in a molecular age – does it still matter in butterfly systematics? Arthropod Structure and Development. 41: pp. 307-322.