Bertanne Visser

Research interests

The main aim of my PhD-research has been to unravel how and why parasitic insects have lost the ability to synthesize lipids in their adult life-stage. Using an evolutionary and genomic approach, I have shown that the loss of lipogenesis is restricted to parasitic insects through lack of transcription of the key gene involved in lipid synthesis. I have further looked at the role of host manipulation in driving the loss of this essential metabolic trait and how nutrient intake affects important life history traits, such as reproduction and survival.

Selected Publications

Visser, B. and J. Ellers (2012). Effects of a lipid-rich diet on adult parasitoid income resources and survival. Biol. Control 60: 119-122.

Le Lann, C., B. Visser, J. van Baaren, J.J.M. van Alphen and J. Ellers (2012). Comparing resource exploitation and allocation of two closely related aphid parasitoids sharing the same host. Evolutionary Ecology 26: 79-94. PDF file

Ellers, J., B. Ruhé and B. Visser (2011).Discriminating between energetic content and dietary composition as an explanation for dietary restriction effects.In press Journal of Insect Physiology, 57: 1670-1676.PDF file

Visser, B., C. Le Lann, F.J. den Blanken, J.A. Harvey, J.J.M. van Alphen and J. Ellers (2010).Loss of lipid synthesis as an evolutionary consequence of a parasitic lifestyle. Proceedings of the National Academy of Sciences of the United States of America, 107: 8677-8682.PDF-file

Research project

Parasitism and the evolutionary loss of lipogenesis

Animals can adapt to fluctuating food conditions by accumulating energy reserves and so reduce unfavorable effects of a low food supply on their growth and survival. However, within the Hymenoptera, several parasitoid species have been shown not to accumulate excess energy in the form of lipid reserves. We hypothesized that the lack of lipogenesis in parasitoids is not confined to adults, but has resulted from selection for lack of lipogenesis in the larval stage. Lipogenesis is costly in energetic terms and parasitoid larvae could benefit directly or through manipulation of the host’s metabolism, which is not possible for herbivorous or carnivorous larvae. To test the idea that lack of lipogenesis is unique to parasitoids because of their parasitic larval life style and to understand how parasitoids avoid detrimental effects on basic cell processes, this research aimed at answering two main research questions:

• How common is the lack of lipogenesis and what is its relation with the parasitic life style?

• What are the underlying physiological and genetic mechanisms explaining the loss of this trait in parasitoids?

This project was the first to investigate the novel hypothesis that there is a link between parasitism and nutrient metabolism on an evolutionary, physiological and genomic level. Using this approach, we were able to unravel important evolutionary transitions in basic mechanisms controlling metabolism and the loss of traits.

Participants: Bertanne Visser, Dan Hahn, Dick Roelofs, Jacques van Alphen and Jacintha Ellers