Dr Julia Ferrari

Senior Lecturer

Research overview


PURE Staff link York Research Database

My research lies at the interface of evolutionary biology, ecology and genetics and concentrates on the ecology and evolution of interspecific interactions. I am particularly interested in symbiotic interactions, and in how symbionts shape interactions with other species.  Microbial symbionts are ubiquitous in eukaryotic hosts, and it is now clear that many of these microbes play key roles in their host’s biology. Symbionts can, for example, allow hosts to thrive on imbalanced food sources, or protect their hosts from environmental challenges such as natural enemy attack or extreme temperatures.

We use aphids, usually the pea aphid Acyrthosiphon pisum, as a model system to study these symbionts. Aphids are known to harbour at least seven species of facultative symbionts with often several symbionts in the same aphid individual.  The pea aphid is a fascinating species that consists of many genetically differentiated host races that are specialised on different host plant species.  This system thus allows investigating complex multitrophic interactions from microbe-plant interactions below ground to aboveground aphid-natural enemy interactions, but remains tractable as it is possible to concentrate on more manageable subsets of this food web at any one time.

For example, we have shown that facultative bacterial symbionts can increase their host’s resistance to parasitoid wasps and fungal pathogens, both natural enemies that would normally kill the aphid.  More recently, we have been particularly interested in co-infections of symbionts.  It is currently unclear how these symbionts affect each other, how stable co-infections can be, but also whether symbionts continue to provide the same benefits to the host while they are coexisting with another microbe species.


Pea aphids on a broad bean leaf.


The parasitoid Aphidius ervi attacking a pea aphid.

Teaching and scholarship

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The main aim of my teaching is to help students acquire skills, knowledge and a good understanding of the scientific process. The focus of my teaching is on facilitating active learning by the students rather than on transmitting factual knowledge. While knowledge is important, I believe that it is crucial to enable students to find information themselves and to be able to identify good quality information. I cover a variety of topics in ecology, evolutionary biology and genetics, and across these disciplines students will have the opportunity to practise field work skills, numerical and problem solving skills as writing and presentation skills.

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My lectures cover a number of topics in evolutionary biology, population and ecological genetics. They are underpinned by a desire to understand ecological and evolutionary dynamics in ecosystems. This often requires learning about conceptual and mathematical models, but with an aim to support learning about biological processes. I encourage students to participate actively in lectures, by using polls, brief discussions and problem solving exercises.

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The topics I offer in tutorials are closely linked to my research interests and a typical tutorial series will be on the evolutionary ecology of insect symbionts. Microbial symbionts in insects have a fascinating biology, affecting many aspects of their hosts’ lifestyles, from nutrition to their interactions with natural enemies. Using this broad theme, students will develop their presentation, essay and report writing skills, as well as the ability to comprehend and analyse the literature, and analyse data. 

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The projects that I offer are usually related to ongoing research, and are typically on evolutionary and ecological questions using aphids as a model system. I encourage students to develop their own ideas and hypotheses, followed by the experimental design. Lab projects will normally involve live insects, entomological techniques and can include molecular approaches. 

Contact details

Dr Julia Ferrari
Senior Lecturer
Department of Biology (Area 2)
University of York
York
YO10 5DD

Tel: 01904 328550