Title: Modelling crop-pest functional interactions under influence of plant genotype and cultural Practices

Host research unit : UR 1115 PSH (Plants and Cropping systems in Horticulture), INRA,
Domaine Saint-Paul, site Agroparc, 84914 Avignon cedex 9, France (http://www4.paca.inra.fr/psh)

Contact : Françoise Lescourret, + 33 4 32 72 24 53, [log in to unmask]<mailto:[log in to unmask]>

Education :
PhD or equivalent. Training in functional ecology and/or agronomy. Experienced in
mathematical modelling and statistics. Skills in community ecology will be appreciated. Ability
and inclination for team-work in a pluridisciplinary framework.

Description of the position :
The context is that of the ecological intensification of horticultural systems (fruit and vegetable
crops) to reduce their reliance on pesticides.

The scientific objective is, to use process-based modelling to develop an integrative view of
functional interactions between cultivated plants and pests under the influence of the plant
genetic characteristics, the pedoclimatic conditions, and the cultural practices. Beyond a single
pest, pest complexes and successions are to be considered. This integrative approach aims at
identifying ways to control pest through plant management, without disconnecting them from
production (quantity and quality) functions. Whilst applied to horticultural crops, this integrated
view will have a broader value by using appropriate case studies and theoretical backgrounds for
modelling.

The idea is to represent in dynamic models (i) how the plant develops characteristics involved in
its sensitivity to/defence against - pest attacks, and how genotype and cultural practices control
this development; (ii) the effect of those characteristics on pest life-history traits; (iii) how these
traits modify the plant functions; (iv) the consequences of those modifications on plant
production and quality.

The work is based on ecological and eco-physiological theories and on results obtained in the
host research unit - i.e. knowledge and already available or newly developed models. Based on
these elements, the junior research scientist will progressively set up a modelling framework using
the principle of parsimony and aiming at an operational generic value (i.e. allowing adaptations to
concrete patho-systems).

Regarding the applications, the project contributes to a cognitive prediction of genetic, cultivation
and environmental effects on horticultural performances. Such prediction is a sound basis for the
model-based design (using skills already present in the host research unit) of innovative cropping
systems combining varieties and cultivation techniques and meeting the requirements of
integrated production.

The position in the host research unit :
The host research unit comprises 11 eco-physiologists working on the whole plant (under
constraints) and the fruit, and a team entitled « Ecology of Integrated Production » comprising 11
agronomists and ecologists working on pest control. The junior research scientist will join this
latter, but he/she will also work with the other scientists to elaborate the models. Modelling is a
major activity in PSH. The unit has experimental facilities, observational devices, technical
partners, and solid networks of scientific partners at the local ("Integrated Horticultural
Production pole"1 with geneticists, pathologists, statisticians, ...), national (especially by means of
its two reference Research Divisions, « Environment and Agronomy2 » and « Plant Health and
Environment3 ») and international levels.

Reference papers of the host research unit in relation with the proposed position :
Gibert, C., Chadoeuf, J., Nicot, P., Vercambre, G., Génard, M., Lescourret, F., 2009. Modelling
the effect of cuticular crack surface area and inoculum density on the probability of nectarine
fruit infection by Monilinia laxa. Plant Pathology 58, 1021-1031.

Grechi, I., Hilgert, N., Sauphanor, B., Senoussi, R., Lescourret, F., 2010. Modelling coupled
peach tree-aphid population dynamics and their control by winter pruning and nitrogen
fertilization. Ecological modelling 19, 2363-2373.

Le Bot, J., Bénard, C., Robin, C., Bourgaud, F, Adamowicz, S., 2009. The 'trade-off' between
synthesis of primary and secondary compounds in young tomato leaves is altered by nitrate
nutrition: experimental evidence and model consistency. Journal of Experimental Botany
60, 4301-4314.

Lescourret F., Génard M., 2005. A virtual peach fruit model simulating changes in fruit quality
during the final stage of fruit growth. Tree Physiology, 25, 1303-1315.

Lescourret, F., Moitrier, N., Valsesia, P., Génard, M., 2010. QualiTree, a virtual fruit tree to study
the management of fruit quality. I. Model development. Trees - Structure and Function
doi : 10.1007/s00468-010-0531-9.