Understanding the factors of invasion of leafy spurge in the floodplains of
the Val de Saône and invasive plant interactions / natural regulators,
in a context of integrated management and biological control by conservation
Matthew Augé
(3); Jean-Marc Contet
(1); Thomas Le Bourgeois
(2); René Sforza
(3) (1)01003 Bourg en Bresse CedexChambre d’agriculture de l’Ain, 4 avenue du Champ de Foire BP 84-(2) Cirad, UMR AMAP 51, TA A51 / PS2, Boulevard de la Lironde 34398 Montpellier Cedex 5
(3) USDA-ARS-EBCL Campus International de Baillarguet CS 90013 Montferrier-sur-Lez
34988 Saint-Gely-du-Fesc
Floodplain in the Val de Saône during flood period
Euphorbia esula in patch Poplars and maize
Agricultural practices in Val de Saone
Leafy spurge root system
Larvae of Oberea erythrocephala Spurgia sp. (Dipt., Cecidomyidae) Gall induced by Spurgia sp. Oberea erythrocephala (Col., Cerambycidae)
The floodplains of the Val de Saône (VDS) are one of the last large flood meadow areas in Europe. Annual floods, and various cultural practices such as mowing and grazing are
the source of a rich floral and faunal diversity protected under the Natura 2000 network. Nevertheless, since the 90s, the native Euphorbia esula (Euphorbiaceae), became
invasive in these particular grasslands.
Leafy spurge grows in dense patches and produce a
latex, toxic to livestock. From 10 to 20% coverage, it
refuses to eat, and all hay containing spurge becomes
unfit for consumption, which causes a loss of
profitability. The economic loss in turn leads to an
ecological risk: the abandonment of meadows or their
conversion into intensive agriculture (maize, poplar)
The innovative aspect of this project is
the sharing of multidisciplinary data for
the study of invasive plant interactions /
natural regulatory / agricultural practices /
abiotic factors. In addition, no biological
control program against invasive plants
have been, to date, made in mainland
France.
The purpose of this
study is to determine the geographical origin of
invasive populations
considered to rule out or confirm the hypothesis that invasive populations would be exogenous to the region or at least
would have a different genetic signature as a result of a process of introduction or
hybridation. For this,
genetic characterization, through adapted
chloroplastic neutral molecular markers
(Weller et al. 2001), will be implemented
Two natural regulators of leafy spurge have been highlighted in the Val de Saône. These biocontrol-agents, used in synergy or not (Guetsky et al. 2002),
could allow the establishment of a program of biological
control by conservation
The hypothesis is that annual mowing in
grasslands prevent the maintenance of high
population densities of insects. Thus, the
purpose of the program is the establishment of refuge areas allowing natural multiplication of biocontrol-agents
(Ruamps-simon 2007). Breeding tests for these two insects will also be lead to achieve
biological control by increasing
Spatio-temporal mechanisms, abiotics, biotics and anthropics factors :
Invasion structure study using all data available (bibliography, field investigation, teledetection)
- Climatic parameters analyse (temperature, flood intensity)
Study of the ante and
post-invasion agricultural practices, in order to know if they are playing a direct role due to a wrong calendar for those practices, or an indirect role on arthropod populations.
Improving knowledges about the invasive species by studying
phenlogy (germination, flowering, fruiting, quantity of seed, plant and roots architecture)
Flowered leafy spurge
Distribution map of leafy spurge samples harvested
2. Understanding the
factors of invasion
3. Natural regulators &
conservation biocontrol
4. Genetic and phylogeography
1. Context
Plots studied in 2006 for biological control
- Oberea erythrocephala (Col., Cerambycidae) a
longhorned beetle. The adult is a defoliator, and larvae are root feeders over winter time.
- Spurgia sp. (Dipt., Cecidomyidae), a gall maker fly, that prevent seed
production (Pecora et al. 1991; Sobhian et al. 2000).
A sample of 11 populations in France, and 17 exotics populations (Italy, Slovenia,
Hungary, Serbia, Poland, Ukraine, Russia,
Czech Republic, USA) has already been done
Several chemical control
programs have been conducted since 2001 by the Chambre
d’Agriculture de l’Ain and the ONCFS, without conclusive
results (Curtet et al. 2008), and a biological control program by raising was conducted in
collaboration with EBCL
between 2004 and 2008 giving random results (Sforza 2009).
Selected littérature: Curtet, L., J. Broyer, J.-M. Contet, and R. Sforza. 2008. La prolifération de l'euphorbe ésule : Une menace pour l'ecosystème prairial du Val de Saône. Faune sauvage 280:8-15. ; Guetsky, R., D. Shitienberg, Y. Elad, E. Fisher, and A. Dinoor. 2002. Improving biological Control by Combining Biocontrol Agents Each with Several Mechanisms of Disease Suppression. The American Phytopathological Society 92:976-985. ; Pecora, P., R. W. Pemberton, M. Stazi, and G. R. Johnson. 1991. Host specificity of spurgia esulae Gagné (Diptera: Cecidomyiidae), a gall midge introduced into the United States for control of leafy spurge (Euphorbia esula L. "complex"). Environmental ecology 20:282-287. ; Ruamps-simon, L. 2007. Optimisation de l'élevage et des lâchers d'Oberea erythrocephala (Col. Cerambycidae) en vue d'une lutte biologique contre l'euphorbe ésule en Val de Saône, Paris-sud 11, Paris. ; Sforza, R. 2009. Projet de lutte biologique contre l’euphorbe ésule (Euphorbia esula L.) en Val de Saône : résultats, bilan et perspectives., Pages 29, Rapport final (2005-08). USDA-ARS. ; Sobhian, R., J. Littlefield, M. Cristofaro, and K. Mann. 2000. Biology and host specificity of Spurgia capitigena (Bremi) (Dipt., Cecidomyiidae), for the biological control of Euphorbia esula L. in North America. Journal of Applied Entomology 124:333-338. ; Weller, S. C., R. A. Bressan, P. B. Goldsbrough, T. B. Fredenburg, and P. M. Hasegawa. 2001. The effect of genomics on weed management in the 21st century. Weed Science 49:282-289.
