Caroline ANSELME

Doctor in molecular biology, Associate professor
Speciality: Evolution and molecular analysis of host–parasitoid interactions
Team: BIPE
caroline.anselme@u-picardie.fr

Research topics

Endoparasitoid wasps are species whose larvae develop by feeding inside the body of insect hosts, leading to their death. Parasitic wasps are the most important natural enemies of arthropods, including those that impair human activities (agricultural pests, invasive species). They are thus major biological control agent and biocontrol efficiency relies to a large extent on the knowledge of the mechanisms leading to successful parasitism and of the agents adaptive abilities. Data on molecules involved in successful host parasitism and host specificity might be very helpful to choose efficient parasitoid strains towards a particular host or even select strains for increased efficiency.

Insect hosts respond to endoparasitism by forming a multicellular melanized capsule around the injected egg. Thus, parasitoid development primarily depends on its ability to evade the host immune responses and also to regulate its physiology. This gave rise to extremely diverse mechanisms to avoid or suppress the host immune response. These most often rely on the co-injection, together with the egg, of maternal factors, also called “virulence factors” (venom or ovarian proteins, particles of viral origin or Virus-like particles devoid of DNA). The outcome of host-parasitoid interactions is thus basically determined by variation for host resistance and parasite virulence. In addition, from the evolution point of view, parasitoid-host interactions impose extreme selection pressures since one of the two insects will invariably perish.

My research interests focus on the evolution of resistance and virulence in host-parasitoid interactions, particularly in Drosophila– Asobara interactions. Parasitoids have developed an astonishing diversity of strategies to manipulate host defenses. Some of these strategies coexist within the same genus of the Asobara braconids, endoparasitoids of Drosophila larvae. Asobara species are a particularly interesting model to highlight the evolution of virulence strategies developed by close relative species.

In the BIPE team, I develop molecular approaches to: 1. identify parasitoid virulence factors; 2. characterize their role in virulence (target(s) in the host, interactions between virulence factors); 3. study their variability within natural populations; 4. compare virulence factors between close relative species (within the Asobara genus) as well as in phylogenetically distant species in collaboration with teams working on virulence of diverse parasitoid species.

Key words

Asobara parasitoid, Drosophila host, Resistance, Virulence, Evolution, Venom and ovarian secretions.

Recent or current projects

Before joining the BIPE lab, I conducted my research in the ESIM team in IBSV UMR INRA in Sophia-Antipolis. This research focuses on the resistance and virulence in host-endoparasitoid interactions on Drosophila (Drosophila – Leptopilina) and aphid (Acyrthosiphon pisum – Aphidius ervi) models. I participated in two research programs funded by the ANR on the characterization of virulence factors of endoparasitoids: first, « Evparasitoid » (2005-2008) and then « Paratoxose » (2009-2012) in which I continue to work within the BIPE team. I am currently working in collaboration with a post-doctoral student, on the characterization of two virulence factors and I initiated a project to sequence the transcriptomes of venom glands and ovaries of three species of Asobara to identify new candidate genes. This transcriptomic approach, combined with physiological, proteomics and population approaches, will identify virulence factors of the three Asobara species. The characterization of these factors and, ultimately,of their target in the host, is essential to understand the variability of virulence strategies in Asobara sp. and the evolutionary origin of this variability.

Provided courses

Cellular and molecular biology
Embryology
Immunology
Animal reproduction.

Recent publications

Le Ralec A., Anselme C., Outreman Y., Poirié M., van Baaren J., Le Lann C., van Alphen JJM. (2010). Evolutionary ecology of the interactions between aphids and their parasitoids. C R Biol. 333(6-7):554-65.
Gerardo NM., Altincicek B., Anselme C., Atamian H., Barribeau S., et al. (2010). Immunity and other defenses in pea aphids, Acyrthosiphon pisum. Genome Biology 11(2):R21. The International Aphid Genomics Consortium (2010) Genome Sequence of the Pea Aphid Acyrthosiphon pisum. PLoS Biol. 8(2): e1000313.
Dubuffet A., Colinet D., Anselme C., Dupas S., Carton Y., Poirié M. (2009). Variation of Leptopilina boulardi success in Drosophila hosts: what is inside the black box? Adv. Parasitol. 70:147-88.
Anselme C., Pérez-Brocal V., Vallier A., Vincent-Monegat C., Charif D., Latorre A., Moya A., Heddi A. (2008). Identification of the weevil immune genes and their expression in the bacteriome tissue. BMC Biol. 6:43.