Le journal de l'IRD
n° 34 March-April 2006
Translator: Nicholas Flay
Abstracts for the international issue
p. 13 IRD World
Patagonia
p.8-9 Research
The Senegal Valley
Mosquito
Aedes albopictus
tours the world
Between polar
climate and
tropical climate…
A well-shared resource
S
S
A new life
for fossil rice!
p. 1 Interview
© IRD/M. Dukhan
Feeding the planet:
no miracle solutions!
Interview with Francis Delpeuch, IRD nutritionist,
joint organiser of the exhibition “Feeding 9 billion humans”1
“
The substantial development of technology and trade over the second half of the
20th century has allowed the production of enough food to feed decently the Earth’s
6 billion inhabitants, at least in theory… The paradox is that, in spite of this success,
human beings are still dying of hunger. Yet this problem has been high on the international political agenda for the past few decades… Increasing the volume of foodstuffs
available, essential as such a condition may be, will not suffice. Indeed, consumers have
to have the means available to obtain them, the food must there when needed, and
people have to have the money necessary to buy it. But beyond these considerations,
the world food system is at a crossroads. In a context of globalization and urbanization,
it is confronted with major changes occurring at an unprecedented speed and scale:
questioning of the priority given to local food-crop production and therefore of peasant
farming, industrialization of food provision with ever longer and more complex food
supply chains, concentration of food industry companies, increasing free trade and globalization of markets, emergence of supermarkets in the developing world, changes in
ways of life and tastes, etc. And finally, there are dominant modes of production and
consumption that raise sharply the question of respect of environmental objectives like
sustainability and biodiversity in food systems. The great variety of food and nutritional
problems, the diversity of situations and the complexity of the causes show well that
these questions cannot be solved merely by producing more foodstuffs, even if it
remains essential to increase production in the poor countries in the long term. Today
the question is no longer one of just food security, but of the implementation of policies not only on food itself but also on nutrition.”
R
eunion Island, aiming to stimulate its agriculture which
is currently relatively uncompetitive, is seeking to develop
a product with high added-value. The idea has been found of restoring the
value and reputation of the coffee variety ‘Bourbon Pointu’, which was grown traditionally
on the island until the end of the XIXth century and which yielded a high-quality coffee.
p. 10 Research
What kind of sustainable development
for the Aïr-Tenere?
© ETH/Urs Gerber
P
Close enemies
tance can take several generations for
plants to acquire. Research is focusing on
this very aspect. The research team
‘Résistances des plantes’ (UMR DGPC, IRDCirad-University of Montpellier II) has
been studying these mechanisms in detail
since the 1990s. Its research deals with
plants that are economically highly important for the countries of the South, like
banana, coffee, cotton or rice. Identification of the most effective defence
strategies for each plant-parasite couple
is enabling the team to identify varieties
having the best resistance in order to suggest them as crop plants.
© IRD/F. Anthelme
© IRD/D. Fernandez
I
n order to survive environmental stress, plants
have developed a variety of
defence mechanisms. Chemical or mechanical barriers, or metabolic changes
can disturb, or even block
completely, the spread of a parasitic disease within the organism. Sometimes,
however, it proves necessary to set more
sophisticated strategies to work. These
involve activation of specific resistance
genes. The plant can adjust its metabolism to favour localized or more generalized resistance in different ways according
to the type of parasite that attacks (fungus, bacterium, virus, nematode, insect).
However, by means of mutations, microorganisms manage to adapt to such
strategies and regain their virulence. The
plant then just has to find another
riposte. In natural conditions, new resis-
1. Gestion de l’Eau, acteurs, usages, Cemagref/
Cirad/Engref/IRD.
a Reunion Island coffee
in search of excellence
p. 7 Research
Plants and parasites
specimen of the fossil rice Oryza has
been found, thanks to the tenacity
of Gérard Second, in a collection of the
Zurich Federal École polytechnique. First
described by the Swiss palaeontologist
Oswald Heer in 1855, it is the only rice
fossil known to this day. It stands as
evidence to confirm the origin of presentday rice. Why is this old specimen attracting so much interest? “At a time when
rice and its main related wild varieties are
among those plants whose genome has
been deciphered the most, this fossil can
bring new proof enabling us to place the
origins of rice in time and space. It allows
us to trace the origin of the Oryzeae tribe
back nearly fifty million years; consistent
with all the recent discoveries in India of
traces of Oryzoideae – the ancestor of
Oryzeae – in fossilized dinosaur droppings, this fossil can lead to a calibration
of the molecular chronology deduced
from DNA sequences.“
use of seasonal rain forecasts made at the
end of July for the following 4 months
by Météo France’s ‘Arpège Climat’
model. A specific knowledge transfer
programme began in 2005 and is continuing in 2006 with the OMVS in order to
strengthen skills of this partner’s staff in
using the tools transferred (4 software
packages for simulation and for water
data management).
p. 11 Valorization
“Bourbon Pointu”
1. Can be consulted on the website www.adpf.asso.fr - heading “adpf publications”.
A
which keep a suitable balance between
the different objectives of the dam: electricity generation, irrigation, regulation of
low water levels.
Refinement of this programming requires
taking into account the potential for
water stock replenishment. The IRD, in
association with Météo France, is for this
reason investigating the problem of seasonal provision of adequate flow levels in
the Senegal. This measure involves the
© IRD/M. Dukhan
p. 1 News
he 1,800-km long River Senegal suffers from the whims of the climate.
Firstly, its natural discharge is highly variable from one year to the next. Secondly,
the overall low level of discharge occurring from the 1970s on and especially a
series of excessively low flooding events
in the 1980s have had disastrous consequences.
The Manantali Dam (Mali) was brought
into service in 1987 as a means of alleviating such a haphazard situation.
It controls about half of the
river’s flow, generates an annual
800 GWh of electricity and allows
the irrigation of 120,000 hectares
of land in the valley. This water
management structure has to
serve several objectives. How can
these be reconciled? Much of the
IRD’s
Reservoir Management
Optimization Programme, conducted between 1997 and 2002,
was devoted to this question. The
Institute set it up at the request of the
‘Organization for the Development of the
Senegal River’ (Organisation pour la mise
en valeur du fleuve Sénégal (OMVS)) which
brings together four West-African countries
(Guinea, Mali, Mauritania, and Senegal).
The Research Unit Gestion de l'eau,
acteurs et usages (UR183-UMR G-EAU1) a set
of analytical methods aiming to optimize
the management of the dam at Manantali (Mali). The software Simulsen can create simulations of reservoir management,
which helps choose management policies
© IRD/B. Pouyau
cientists from the IRD
Research Unit Great
ice (UR032) and from the
Centre for Scientific
research of Santiago
(CECS) in Chile researches
into traces of our past climate that might be held
in the icepacks of the
Southern Hemisphere. In March 2006 they are launching a deep drilling programme on
the border between Argentina and Chile, on the ice that tops the two highest peaks of
Patagonia, San Valentin and San Lorenzo (3,900 and 3,500 m respectively).
A short test drilling exercise was performed in March 2005 on San Valentin in order to
estimate the amount of snow accumulation at its summit. The first results analysed confirm that this site shows all the characteristics expected of a deep-drill emplacement,
except perhaps that of accessibility. Indeed, the mountains of Patagonia are not very
high but the nature of their escarpment, plus the appalling weather conditions that prevail for most of the year, present a real challenge for the most experienced mountaineers.
© Susan Ellis
cientists from the IRD
Research Unit
‘Caractérisation et
contrôle des populations de vecteur’ and
from EID Méditerranée have been investigating the world-wide expansion of a
mosquito that transmits the Chikungunya and dengue viruses, responsible
for epidemics on Reunion Island.
Aedes albopictus is a vector of
arboviruses and is on the way to colonizing the world. It originates from
Asia but has already crossed oceans
and has succeeded in conquering parts
of every continent. The mosquito does
this by colonizing quickly the favourable ecological niches available.
The consequences of these changes
could be two-fold. First, the establishment of an additional vector species
exploiting ecological niches available
could create the risk of circulation of
viruses pathogenic for humans, such as
those behind Chikungunya or dengue
fever, even though it has been demonstrated that Ae. albopictus is not a
good vector of dengue. Secondly, in
the tropical zones, the substitution of
Ae. aegypti by Ae. albopictus could
bring changes in the epidemiology of
arboviral diseases, decreasing the risk
of transmission of yellow fever (for
which a vaccine exists) and modifying
the risk of dengue transmission (for
which no preventive medicine is available).
T
© IRD/J.P. Lamagat
p. 3 News
opulation pressure, agriculture intensification and drought are threatening the fragile biodiversity of the Aïr-Ténéré nature reserve. Research scientists from the
University of Niamey and from the IRD are studying the ecosystems of this protected area.
They are assessing the impact of current changes so that, over the long term, conservation and development can be reconciled in this region designated by Unesco as part of
World Heritage. Successive droughts have aggravated the effects of overexploitation of
the area’s environment by people and their livestock, resulting in severe deterioration
of plant cover, especially in the savannahs which, in terms of resources, are the most
important ecosystems. As Fabien Anthelme, IRD research officer, stresses, “We have found
evidence that many plant species use tufts of Panicum turgidum (of the Poaceae family)
as refuges from a hostile environment”. P. turgidum favours the development of Acacia,
in one way by protecting it effectively from herbivorous animals; and in another, by
decreasing the daily amplitude of temperature differences and reducing water loss in
plants living in association with it, during the hottest parts of the day. In the centre and
the south of the Aïr region, on the banks of koris (temporary rivers), gardens, small irrigated areas of cultivation (1 to 2 hectares),
have been growing in number over the
past ten or so years. The people living in
the reserve and around its edges are faced
with a choice: either a production-oriented
approach taken to the extreme which
could have disastrous consequences for
this fragile ecosystem; or, conversely, a reasoned agriculture, less profitable in the
short term, but which could be the key to
a sustainable form of socio-economic
development in the Aïr.
Consult the articles in full on the IRD Internet site : http://www.ird.fr