Aude COUTY

Doctor, Lecturer
Speciality: Entomology, chemical ecology, tritrophic interactions
Team: BIPE
aude.couty@u-picardie.fr

 

 

Research topics

Sustainable management of agroecosystems requires the development of Integrated Pest Management (IPM) strategies against crop pests. However the development of such alternative strategies requires a better understanding of the interactions established between the different protagonists: plants (trophic level I) – phytophagous insects (trophic level II) – entomophagous insects (trophic level III). My research in the BIPE laboratory primarily revolves around the study of these interactions between different trophic levels. More recently, I have also been involved in the development of projects on the impact of exotic organisms in local ecosystems and agroecosystems.

Key words

parasitoid, aphid, drosophila, chemical ecology, tritrophic relations, behaviour, olfaction, electro-penetrography (EPG), olfactometer.

Recent or current projects

Host-parasitoid immune interactions
In insects, parasitic infestation results in the establishment of an immune defense reaction by the host involving cellular and humoral mediators. The parasites have developed virulence strategies to hijack the defenses of their host, and the degree of virulence can vary within a species. Parasites may also encounter different degrees of « immune resistance » in their hosts, particularly in hosts of related species. To address this issue, the system used in our laboratory is composed of endoparasitoid insects of the genus Asobara (Hymenoptera, braconid), and their hosts, the larvae of Drosophila.

We study the various mechanisms of virulence used by parasitoids and of resistance developed by their host (s), by analyzing the factors produced and injected by the parasitoids and the factors with which they interact in the host, whether resistant or susceptible. I was involved in an ANR project (« Evparasitoid » No. NT05-4_42192, 2005-2008) which aimed at a comparative approach by analyzing the host / parasitoid interactions at the molecular and cellular mechanisms but also at an evolutionary scale. Currently, I am involved in a study designed to examine the physiological cost of a particular virulence strategy developed by females of A. tabida (« camouflage » of eggs within host tissues).

Impact of temperature increase on host/parasitoid interactions
Climate change will primarily affect species unable to regulate their internal temperature and especially insects. We participate in a wide ANR project (CLIMEVOL 2009-2012) which focuses on the effect of climate change on the evolution of host-parasitoid interactions, from the molecular level to the level of insect communities. In this context, I have participated in a study on the effects of elevated temperature on the « resistance / virulence » interaction in the system Drosophila melanogaster / Asobara tabida.

On the other hand, we have also undertaken to investigate the effect of moderate heat stress on a host / parasitoid system of agronomic interest. I co-supervised a PhD thesis (2007-2011) which aimed to investigate the consequences of such heat stresses on the life history traits of the biological control agent  Aphidius ervi, a parasitoid of the  potato aphid Macrosiphum euphorbiae.

Pesticide treatments: effect on pests and their natural enemies
Effect of mineral oil on potato aphids
Potato aphids (Macrosiphum euphorbiae and Myzus persicae) pose many problems for farmers including the transmission of phytoviruses to their host plant. To limit these viral infections, the only preventive measure is a weekly application of mineral oil on plants. The objectives of this project are to characterise the nature (mechanical, antibiosis or antixenosis) and modes of action (direct effects on aphids or indirect effects via a change in the physiology of the plant) of these distillates.
I participated in the supervision of a thesis (2006-2009) on this subject (CIFRE, No. 840/2006, in partnership with the Research Station of the GIE Comité Nord « HUMIPOM: Mineral oils and the protection of potato crops « )

Effect of a specific systemic insecticide against aphids on beneficial insects
The Plenum (active ingredient, pymetrozine from the chemical family of azomethine pyridines), a relatively new insecticide, allows to specifically targets plant sucking insects by acting on their feeding behaviour and thus supposingly limits its potential impact on natural enemies.
The work done in the laboratory was to study the effect of the Plenum of the aphid parasitoid Aphidius ervi and the honeybee Apis mellifera via a behavioral and toxicological approach.

Impact of exotic organisms on french agroecosystems and ecosystems
Impact of the introduction of miscanthus on local agroecosystems
This project aims to study the impact of the introduction of miscanthus, a perennial biomass crop of interest, on the insect fauna and especially on aphid vectors of pathogens in field crops in the North of France, and on their associated natural enemies. This work will extend our knowledge of the interactions and biological flows of potential crop pests and beneficial insects between the introduced plant, miscanthus, and local crops (potato, wheat, sugar beet). In addition, several works in genetic improvement showed a variability of biomass production depending on the species studied, the clone, but also according to the ploidy level. The selection of a plant variety also requires the characterisation of resistance towards crop pests. We will consider the effect of inter-and intraspecific variability, within the genus Miscanthus, on the key steps of aphid colonisation:

Drosophila Suzukii, a new crop pest in France
Drosophila Suzukii is a polyphagous pest that attacks many plant species and especially cherries, apricots, peaches, berries and strawberries. This drosophila species of Asian origin was detected in France in 2010 and has been listed on the warning EPPO list (European Plant Protection). D. suzukii exhibits the particularity of infesting preferentially unmature fruits before harvest. I am particularly interested in studying how this fruit fly researches its hosts  (wild or cultivated fruits) through olfactometer studies.

Teaching courses

I teach in all years from the first year until the master’s degree. Currently, I am responsible for two modules of the third license year (zoology and behavioral ecology), one EADD Master module (chemical and behavioral ecology) and a module from the MASTER SVTU preparing the Biology CAPES (Evolution and phylogeny). 

PhD supervision or co-supervision

2007-2011 Ibrahim Ismaïl Effects of heat stress on the life history traits of Aphidius ervi (Aphidiidae), an aphid parasitoid used as a biological agent.

Selected publications

Couty A., van Emden H., Wadhams L.J., Perry J., Hardie J. and J.A. Pickett. (2006). Comparisons between roles of vision and olfaction in host-plant finding by Plutella xylostella (Lepidoptera: Plutellidae). Physiological Entomology. 31 (2): 134-145.
Kaiser L., Couty A. and Perez-Maluf R. (2009). Dynamic use of fruit odours to locate host larvae: individual learning, physiological state and genetic variability as adaptative mechanisms. In G. Prévost (editor): Advances in parasitology, Academic Press, Burlington. 70: 68-95.
Joseph J.-R., Ameline A. et  Couty A. (2010). Effects on the aphid parasitoid Aphidius ervi of an insecticide (Plenum®, pymetrozine) specific to plant-sucking insects. Phytoparasitica, 39: 35-41.
Martoub M., Couty A., Giordanengo P. et Ameline A. (2011). Opposite effects of different mineral oil treatments on Macrosiphum euphorbiae survival and fecundity. Journal of Pest Science, 84: 229-233.
Boquel S., Delayen C., Couty A., Giordanengo P. et Ameline A. (2012). Modulation of aphid vector activity by potato virus Y on in vitro potato plants. Plant disease, 96: 82-86.