Biodiversity conservation is key

Dominique Dumet,

Researcher sorting bambara groundnut seeds, IITA genebank. Photo by J. Oliver.
Researcher sorting bambara groundnut seeds, IITA genebank. Photo by J. Oliver.

Biodiversity or biological diversity is the variety of life on earth; it includes all living forms, animal, plant, or microbial. It is accessible at three levels: ecosystems, species within the ecosystem, and genes within the species. Today, 65 million years after the fifth and largest notable extinction of species (that wiped away the dinosaurs), alarming reports state an unprecedented rate of biodiversity loss—maybe the sixth extinction (Eldregde 1999).

The loss of spectacular trees in the rainforests or of polar bears at the North Pole is well-publicized and of great concern. However, equally worrying but so much less acknowledged is the loss of agricultural biodiversity. Agrobiodiversity refers to the part of biodiversity that feeds and nurtures people—whether derived from the genetic resources of plants, animals, fish, or forests. The diversity of these genetic resources is the foundation for sustainable agriculture and global food security. It enables plants to adapt to new pests and diseases as well as to climatic and environmental changes.

There are two complementary methods to conserve plant genetic resources: ex situ (in an artificial environment) and in situ (in a natural environment). Both approaches have pros and cons. In situ conservation allows further evolution of germplasm in natural conditions, but ex situ conservation allows ready access to clean germplasm.

Since its establishment in 1967, IITA has devoted considerable resources to ex situ conservation. In 1975, the Genetic Resources Unit was created to collect, conserve, and study food legumes, roots and tubers, and their wild relatives. Today, IITA’s Genetic Resources Center (GRC) maintains over 28,000 accessions of six main staple crop collections: black-eyed pea (cowpea), maize, soybean, cassava, yam, and banana. The biggest collection is of cowpea, with over 15,000 accessions collected or acquired in or from 89 countries, mainly in Africa. This biodiversity is very valuable for further genetic improvement and food security. It is maintained in trust for the international community and is available to all.

Any new sample entering the genebank is given a “passport” and a unique accession number. The passport holds important information related to the background of the accession. Such data, and in particular the georeference, i.e., the exact location where the sample was collected, provide valuable information. Indeed, when searching for drought tolerance traits, breeders may want to give priority to samples collected in dry areas. The analysis of georeferences of accessions also shows any potential ecogeographical gaps in the collection. Finally, the genetic erosion of a crop can be assessed during recollecting missions based on vernacular names and georeferences of already collected accessions. Unfortunately, for most collections, passport data are far from complete; the country of origin may be known, but the georeferences are missing. This lack of information is partly because the importance of passport data was underestimated in the past.

Diversity of crop genetic resources in the IITA genebank. Photo by IITA.
Diversity of crop genetic resources in the IITA genebank. Photo by IITA.

A collection of biodiversity is traditionally measured at the accession level using phenotypic characterization and evaluation descriptors. The former category generally refers to highly heritable, easily seen, measured, and expressed descriptors. The second includes descriptors that are more sensitive to the environment, such as yield or pest and disease resistance. Among the 52 international descriptors used to describe cowpea diversity, some quantitative traits show a high rate of diversity. Cowpea pod length varies from as little as 5.6 cm up to 49.9 cm, depending on the accession.

Vegetative trait diversity can be equally spectacular. Depending on the accession, the number of days required to harvest the first mature pod varies from 49 to 129 days after planting. In the context of global climate change and the shortening of the rainy season, such a descriptor is of high interest to the breeding community. Although it is important to capture diversity for today’s breeding interests, it is equally important to capture “neutral” diversity. Something that has no direct use for improvement today may become valuable in the future.

Since the 1980s, the development of molecular tools has had a substantial impact on biodiversity characterization. This fast-evolving tool provides increasingly efficient, precise, and cost-effective methods of managing collections. Where the combination of passport and phenotypic descriptors fails to identify duplicates, molecular methods provide a new tool for discriminating and identifying. It is also used to detect the potential loss of genetic integrity, whether associated to conservation or regeneration. IITA is presently fingerprinting the international collections of yam and cassava.

The genetic resources of one given crop are classified in three gene pools based on their respective compatibility/incompatibility to produce viable and fertile progeny (Harlan and de Wet 1971). Gene pool I includes the crop species itself and its wild progenitor. Gene pools II and III include other species that are related to yet different from the crop species of interest (Gepts 2006). Gene pool I is generally well represented in ex situ collections but gene pools II and III have often been neglected, although they represent a valuable reservoir of untapped genes as they evolved independently of human preferences.

Africa is a center of diversity for two of the crops maintained at IITA: cowpea (Vigna unguiculata) and yam (Dioscorea spp.) (Padulosi 1993, Orkwor et al 1998). IITA has devoted considerable resources for conserving the wild relatives of Vigna. However, efforts are still needed to further collect more wild relatives and cultivated cowpea. Although generally African biodiversity remains rich, various threats exist. Climate change attracts most attention in this matter but agriculture intensification should not be overlooked. The paradox is that research in agriculture requires diversity to build on existing traits but is one of the main threats to that vital biodiversity.

IITA is planning a collecting mission for cowpea in 2010 in regions of Nigeria where collecting had not been done and will focus on two species: V. unguiculata var. spontanea (gene pool I) and V. unguiculata subsp. baoulensis (gene pool II). Remi Pasquet, a taxonomist expert for cowpea from the International Centre of Insect Physiology and Ecology (icipe), will lead the expedition.

Researcher checks tissue culture-grown cassava. Photo by Jeffrey Oliver, IITA.
Researcher checks tissue culture-grown cassava. Photo by Jeffrey Oliver, IITA.

Over the last 30 years, there has been a profound change in the legal landscape with regard to ownership of biodiversity in general and crop genetic resources in particular (Gepts 2006). In the past, biodiversity was considered a common heritage of humanity, but in 1992, the Convention on Biological Diversity (CBD) assigned sovereignty over biodiversity to national governments. CBD is the first legally binding framework for the conservation of biodiversity that recognizes the “knowledge, innovations, and practices of indigenous and local communities and encourages the equitable sharing of benefits arising for the utilization of such knowledge, practices, innovation, and knowledge” (Shand 1997).

More recently, the International Treaty on Plant Genetic Resource for Food and Agriculture reconsidered the question of sovereignty over plant genetic resources. It promotes the exchange of germplasm for 64 crops in a multilateral agreement (multilateral system, MLS). Within this frame, the conservation of plant genetic resources, i.e., the future of food security, relies on shared initiatives and responsibility and the construction of a global system. Within this system, each stakeholder has a role based on comparative advantage—whether it is access to germplasm, technology, human resources, or capacity development.

The opening of the Svalbard seed vault in Norway, in 2008 is one of the building blocks of the global system. Such an initiative caught the attention of the media and, consequently, directed the attention of the world on the erosion of plant diversity. It is somehow reassuring to know that part (even a little) of plant diversity is now kept in a place that is naturally clean, cool (energy efficient), isolated (as the North Pole), and protected (by polar bears). However, not all plant diversity can be conserved in Svalbard. In fact, many species producing so-called recalcitrant seeds as well as those clonally propagated cannot be maintained at low temperatures for various physiological reasons. These problematic species, which in IITA’s collections include yam, cassava, and banana/plantain, are generally banked in the field or in vitro slow-growth conditions. The latter approach is preferred as it protects germplasm from field biotic and abiotic risks and allows easy access to distribution of clean material.

The ultimate in vitro conservation approach is cryopreservation (conservation at very low temperatures, generally at –196 °C). At such a temperature, all biochemical and biological processes are stopped. Thus, plant tissue can, in theory, be stored forever. IITA has recently developed such a process for cassava (Dumet et al. accepted).

Whatever the ex situ conservation approach, it will never be preferable to in situ conservation. However, whenever biodiversity preservation poses a threat to human livelihoods, comfort, or convenience, the politically expedient choice is usually to “liquidate” the natural capital (Ehrlich and Pringle 2008). It seems unlikely that more natural space will be available to ensure the safety of biodiversity in the future…This is not impossible, however, if the schools are involved in teaching the value of biodiversity to the younger generations.

Dumet, D., S. Korie, and A. Adeyemi. (accepted by Acta Horticulturae) Cryobanking cassava germplasm at IITA.

Ehrlich, P.R. and R.M. Pringle. 2008. Where does biodiversity go from here? A grim business-as-usual forecast and a hopeful portfolio of partial solutions. PNAS. Vol. 105, suppl. 1.

Eldregde, N. 1999. An original article.

Gepts, P. 2006. Plant genetic conservation and utilization: the accomplishments and future of a societal insurance policy. Crop Science 46:2278–2292.

Harlan, J.R. and J.M.J. de Wet. 1971. Towards a rational classification of cultivated plants. Taxon. 20:509–517.

Karp, A. 2002. The new genetic era: Will it help us in managing genetic diversity. In: Engels, J.M.M., V. Ramanatha Rao, A.H.D. Brown, and M.T. Jackson, eds. Managing Plant Genetic Diversity. Wallingford and Rome, CAB International and IPGRI, pp. 43–56.

Orkwor, G.C., R. Asiedu, and I.J. Ekanayake. 1998. Food yams: Advances in research, IITA and NRCRI, Nigeria.

Padulosi, S. 1993. Genetic diversity, taxonomy and ecogeographic survey of the wild relatives of cowpea (V. unguiculata). Ph.D. thesis, University of Louvain la Neuve, Belgium.

Shand, H. 1997.

Insect biodiversity for sustainable management of natural resources

Georg Goergen,

Insect diversity: Tenebrionidae family checklist. Photo by G. Goergen, IITA.
Insect diversity: Tenebrionidae family checklist. Photo by G. Goergen, IITA.

The conservation of biodiversity and the sustainable use of natural resources are guiding principles of the CGIAR and a recognized thematic priority area. The CGIAR is a major player in the collection, characterization, and unrestricted distribution of agrobiodiversity resources and related information on a global scale. Currently, out of 15 centers, 11 house important genebanks amounting to some 650,000 accessions. These provide scientists with the genetic material needed to significantly increase agricultural productivity.

The conservation of genetic resources at IITA is particularly broad in coverage. Thus, collections encompass a wide range of organisms including plants but also associated nonplant biodiversity. Emphasis is placed on the ex situ preservation of plant genetic material. This is reflected in the maintenance of roughly 28,000 germplasm accessions from 19 agricultural crops and their wild relatives. More than half of the genebank’s holdings represent in-trust collections of cowpea for which IITA has received the world conservation mandate. Free and unrestricted public access to this genetic material is ensured through institutional compliance with the international seed treaty developed through the Food and Agriculture Organization with the strong involvement of the CGIAR centers.

Apart from the use of genetically improved crops, agricultural productivity is also strongly influenced by a rich in-field biodiversity comprising organisms such as fungi, bacteria, viruses, nematodes, mites, and insects. Their beneficial or deleterious impact on crops is relatively well understood when interactions are based on simple associations of organisms. However, when many players are acting sometimes across several trophic (nutrition or feeding) levels, the study of ecosystems becomes complicated and knowledge-intensive.

Immature of the whitefly Paraleyrodes minei. Photo by G. Goergen.
Immature of the whitefly Paraleyrodes minei. Photo by G. Goergen.

Generally, a thorough inventory and characterization process is the requisite condition for the sustainable management of this nonplant biodiversity. Related information is primarily stored in research collections to which IITA has been giving growing attention over the last decade. Today, important nonplant collections allow safe diagnostics of plant pathogenic microorganisms used for resistance screening in breeding programs and arthropods/fungi used for biological control (see Korkaric and Beed, this issue).

A collection that has particularly expanded over the last 15 years is the arthropod reference collection at IITA-Bénin, the largest within the whole CGIAR. It encompasses currently more than 350,000 specimens collected in a wide range of agricultural and natural environments throughout West Africa. More than 5,000 species from 330 arthropod families have been identified from the sampled material, but it is estimated that about 40−50% of all known insect biodiversity of the subregion is preserved in this collection, awaiting further study. Serving as the coordination center for the West African node of the global taxonomic network BioNET-INTERNATIONAL, this biodiversity collection is well placed to provide essential services for sustainable natural resource management at the regional level.

The most important service has been the assistance in arthropod identification. Similar to the safe characterization of germplasm when plant material is transferred under the International Treaty on Plant Genetic Resources for FAO, users need reliable and valid entity names for biodiversity monitoring, pest management, biological control, conservation, and compliance with trade-related controls under the prevailing Sanitary and Phytosanitary regulations of the World Trade Organization.

For scientists, farmers, extension and biosecurity agents, quarantine authorities, and any other user throughout the globe, accurate and timely identification is vital. It represents the unique entry point for access to existing information about any organism. Opportunities in West Africa similar to diagnostics services for plant diseases for identifying arthropods are scarce or nonexistent and fees requested by overseas centers of expertise are not affordable for most local users. Thus, by providing the names of, on average, 1,500 submitted arthropod specimens per year, IITA has been instrumental in responding to the regional need for over a decade.

Adult female of Sri Lanka fruitfly Bactrocera invadens. Photo by G. Goergen, IITA.
Adult female of Sri Lanka fruitfly Bactrocera invadens. Photo by G. Goergen, IITA.

Arthropods form the bulk of the roughly 1.8 million species that have been described until today. It is estimated that this number actually represents only a small fraction of all living organisms, the number of yet unnamed species being particularly large in tropical countries. Thanks to regular faunistic activities, IITA has contributed to the discovery and description of more than 120 arthropod species previously unknown to science. Among them are important pests and their natural enemies.

Following climate change, invasive alien species (IAS) are widely regarded as the second-greatest threat to biodiversity worldwide. They represent a growing concern for biosecurity and quarantine services, especially since increased trade and travel are expected to accelerate the rate of pest introductions. For tropical Africa, data sampled over 100 years show a rate of three introductions every two years. The failure to recognize IAS may have dire economic or ecological consequences. Prevention or early detection of such IAS requires considerable knowledge of native and exotic fauna.

For West Africa, IITA-Bénin is at the forefront of IAS surveillance with the detection of the whitefly Paraleyrodes minei Iaccarino, the Sri Lanka fruitfly Bactrocera invadens Drew et al., and lately the papaya mealybug Paracoccus marginatus Williams & Granara de Willink. Such monitoring also led to the recent detection of a new cashew pest, now awaiting description.

Infestation of the papaya mealybug Paracoccus marginatus. Photo by Manuele Tamo, IITA.
Infestation of the papaya mealybug Paracoccus marginatus. Photo by Manuele Tamo, IITA.

Despite the need to maintain the present services and the opportunities arising to work in new fields, the future of the collection remains unsure because of the lack of external funding. This is all the more surprising since new opportunities for the delivery of public goods are now appearing in various areas with significant impact for the sustainable use of natural resources. Thus, the comparatively young age of the collection makes it particularly well suited for the application of novel identification methods such as DNA barcoding.

IITA’s participation could thereby provide important additions to this publicly accessible DNA database thus advancing the goals set by the Consortium for the Barcode of Life (CBOL). Besides agricultural pests and their natural enemies, this technology will also target crop pollinators because of their vital services to ecosystems and the particular concern raised by their global decline. Thus, a full return from past collection efforts will be achieved by applying molecular techniques.

Opportunities to extend biosystematics services at IITA are manifold and crucial for the region that is known to suffer from scanty local capabilities. These include the development of web-based products, the integration of Geographical Information Systems, the provision of online identification tools using high resolution images of important West African arthropod species, and capacity building in the identification of agriculturally relevant groups at various academic levels.

IITA has already an undeniable comparative advantage in biosystematics. This advantage should be preserved in view of its vital support to the successful deployment of plant genetic material for improving food security and reducing poverty in developing countries.

Why manage noncrop biodiversity

Muris Korkaric, and Fen Beed,

When it comes to the diversity of nonplant taxa, the numbers alone are highly impressive. There are an estimated 5–30 million species of microorganisms globally but only two million have been formally described. In 1 g of soil, over a billion bacteria cells can be found, but fewer than 5% of the species have been named or can be grown on artificial media. For fungi, about 1.5 million species are estimated to exist and yet only 5% have been characterized taxonomically.

Disease symptom caused by Colletotrichum fuscum on lettuce leaf. Photo by F. Beed, IITA.
Disease symptom caused by Colletotrichum fuscum on lettuce leaf. Photo by F. Beed, IITA.

Nematodes remain particularly poorly described with only a fraction of the suspected half million found in nature known to man. For insects, arachnids, and myriapods only 1.1 million have been named from a potential 9 million. These numbers compare with an estimated 420,000 seed plants of which most have been described.

Knowledge of biodiversity is uneven, with strong biases towards the species level, large animals, temperate systems, and the components of biodiversity used by people. Although biodiversity underlies all ecosystem processes, modern agriculture is based on a very limited genetic pool of crops and an even more limited exploitation of the genetic resources of nonplant taxa.

This is surprising, considering that as a consequence of their diversity microorganisms and insects play pivotal roles across ecosystems that far exceed those of plants. They provide critical functions and services for food and agriculture. They are indivisibly connected with ecosystem resilience, crop health, soil fertility, and the productivity and quality of food. Modern agriculture in the developed and especially the developing world uses only a small fraction from this rich pool of genetic resources.

Conserving and using nonplant taxa
One of the vital pillars in the work of the Consultative Group on International Agricultural Research (CGIAR) is the conservation and use of agrobiodiversity and related knowledge. Over 650,000 accessions of crop, forage, and agroforestry genetic resources are stored and maintained through the centers’ genebank system and distributed to researchers and breeders throughout the world.

However, scientists from different CGIAR centers are also involved in collection, conservation, and sustainable use of insects and mites, fungi, bacteria, viruses, and nematodes that are either beneficial or antagonistic to crops. These research collections are used in two main areas: (1) crop health and productivity, where the collection supports screening for resistance in breeding programs, pathogen diagnostics, and the development of biological control technologies, and (2) soil health, fertility and ecosystem resilience where for example, collections support the development of biofertilizers.

IITA’s main collections of nonplant taxa are housed at the stations in Ibadan (Nigeria) and Cotonou (Bénin). At the headquarters in Ibadan, the collection and study of plant pathogenic fungi, bacteria, and viruses of important crops are coordinated and collections are maintained. Examples are those for yam and cassava anthracnose, cassava bacterial blight, and soybean rust pathogens.

Aflatoxin-producing fungus Aspergillus flavus growing out of maize grains in a culture medium. Photo by J. Atehnkeng.
Aflatoxin-producing fungus Aspergillus flavus growing out of maize grains in a culture medium. Photo by J. Atehnkeng.

Some of the collections contain large numbers of isolates of the same species which are often unique, not being found elsewhere in the world. International repositories might hold many different species, but tend to store fewer isolates per species and rarely prospect across the developing world. A diverse range of isolates gives a more complete representation of the genetic diversity which can be crucial for understanding evolutionary patterns, pathogen variation, and population dynamics. It helps breeding programs to identify targets for resistance selection.

Collections of isolates of the same species can be used to develop appropriate biocontrol technologies. One such example is IITA’s collection of Aspergillus flavus, a fungus that normally produces aflatoxin, a compound that is toxic to humans and animals. Over 4,500 strains have been collected from Nigeria alone and screened for toxin production and their ability to outcompete other strains when found simultaneously on foodstuffs. The atoxigenic and most competitive strains have been used to formulate aflasafe®, a biocontrol product (see R4D Review September 2009 issue).

Also in Ibadan, collections of beneficial soil microorganisms are studied and maintained. These organisms (such as Rhizobia spp. and mycorrhizae) enhance the nutrient uptake of leguminous crops and can be used as biofertilizers.

At IITA-Bénin, microorganisms and arthropods have been characterized and preserved for use in biological control programs to manage invasive crop pests and weeds. Plant pathogens have been identified and stored since the deployment of appropriate control measures first requires definitive identification of the causal agent of the disease. The biodiversity center maintains over 360,000 insect and mite specimens and is one of the largest reference collections in West Africa (see R4D Review September 2009).

Other IITA stations keep smaller working collections of nonplant taxa. At IITA-Uganda, collections of nematodes, bacteria, and fungi are maintained—mainly those associated with banana production. Certain Fusarium strains, for example, are used for endophyte-improved banana tissue culture for enhanced pest and disease resistance.

Looking like strung beads, these are part of a sample of insects received by the IITA biodiversity center in 12 months. Photo by G. Goergen, IITA.
Looking like strung beads, these are part of a sample of insects received by the IITA biodiversity center in 12 months. Photo by G. Goergen, IITA.

IITA is a lead organization for the conservation and use of nonplant taxa across sub-Saharan Africa. It is now characterizing nonplant taxa collections across the CGIAR as part of the World Bank-funded GPG2 project (Phase II of the Collective Action for the Rehabilitation of Global Public Goods in the CGIAR Genetic Resources System). This is the first system-wide inventory and collation of the existing global, nonplant taxa collections. The aim is to provide a coordinated and harmonized service for research and use of noncrop taxa to support durable farming systems in the developing world.

Future challenges and opportunities
There is a growing appreciation of the fact that farming occurs in an ecological context with complex interactions between crop and nonplant taxa that can be beneficial or antagonistic. There is also increasing demand for sustainable and environment-friendly solutions to manage pests and diseases, with the expectation that the biopesticide market share will increase to over 4.2% by 2010 and, for the first time, reach a market of over US$1 billion. Due to the rate of population increase the World Bank estimates that the global demand for food will double within the next 50 years. At the same time, the amount of arable land is decreasing from pressure from nonfarming activities and the unsustainable farming practices that are causing losses in soil fertility. This scenario is exacerbated by the fact that 40% of what is grown in the world is lost to weeds, pests, and diseases. In developing countries it is common for up to 70% of the yield to be lost due to attacks from insects and microbial diseases.

Therefore, agricultural production needs to be intensified and more marginal land used to produce sufficient food. This requires the deployment of improved land management techniques combined with the selection and distribution of appropriate crop and noncrop germplasm to exploit interactions with beneficial nonplant taxa and resist increased pressure from antagonistic nonplant taxa. Other factors such as climate change are likely to add new layers of complexity to these challenges. To predict risk and develop appropriate adaptation strategies, CGIAR and governments will become increasingly reliant on knowledge of and access to nonplant taxa genetic resources for food and agriculture. This will be used for research, training, or direct use in agriculture and originate, or be found, in a range of countries or centers.

Collections form the mechanism through which information and access to nonplant taxa can be obtained, but the survival of these collections is under threat from funding constraints. Appropriate policies, investments, and collaborations among CGIAR centers and with international collections are urgently needed to recognize noncrop taxa as global public goods. This would facilitate the conservation of collections, increase their visibility, and maximize their use for the benefit of sustainable farming systems. Especially in Africa, where the biodiversity is high, but the taxonomic and technological capacity is limited, work is needed to manage the full potential of nonplant taxa for food and agriculture.

A research park for Africa

John Peacock,

The IITA campus is a rich center of biodiversity. Because of the protection and nonexploitation of a patch of secondary forest, lakes, and other natural resources in the area, it represents a wealth of flora and fauna that are not common in other parts of Nigeria.

IITA campus, Ibadan, Nigeria. Image from Google Maps.
IITA campus, Ibadan, Nigeria. Image from Google Maps.

IITA was established in April 1967. Earlier in October 1965, approximately 1,000 ha of land were acquired, lying between Ojo in Ibadan town and Moniya villages. The land was covered mainly with oil palms, cassava, maize, cocoyam, and a variety of indigenous trees and climbers.

Today, 43 years on, the area is taken up by research, administration, and residential buildings, lakes, experimental plots, and 350 ha of valuable secondary forest. An arboretum was established in 1979 containing 152 different tree species; 81 of them are indigenous. In addition, the residential and administrative areas of IITA were extremely well landscaped with a diversity of both indigenous and exotic trees. Many of the original hardwood trees were left in situ.

Young Milicia excelsa (Iroko). Photo by J. Peacock.
Young Milicia excelsa (Iroko). Photo by J. Peacock.

Although protected, the forest is still a degraded secondary forest. It is basically four layered, made up of a discontinuous emergent canopy dominated by Milicia excelsa (Iroko), Celtis zenkeri, Terminalia superb, and Antiaris africana; a tree canopy made up of Blighia sapida, young Ceiba pentandra, Entandrophragma angolense, and Ricinodendron heudelotii as the more frequent woody plants. The shrub layer is composed mainly of Newbouldia laevis and Baphia nitida with seedlings and saplings of typical canopy emergents such as Mammea africana. The herb layer is highly diverse containing members of the family Orchdaceae and some Poaceae and Chromolaena sp. in the more open areas (Hall and Okali 1978, 1979).

The IITA forest provides a good habitat for a great number of different insects and birds. It is one of the Birdlife International Important Bird Areas (IBA) with 350 species, including the Ibadan Malimbe, Malimbus ibadanensis, which is endemic to this region.

Knowledge about the diversity of butterfly species at IITA is incomplete. A preliminary survey conducted by lepidopterist Robert Warren in 2002−2009 has confirmed the presence of 149 species (See Warren, this issue). This figure is considered low and could be as high as 400.

Pararistolochia goldieana. Photo by IITA.
Pararistolochia goldieana. Photo by IITA.

In December 1987, a group of enthusiastic volunteers from IITA embarked on carving out a nature trail in the forest. Many useful plant species including herbs, medicinal plants, fiber-producing plants, and fruit and timber trees can be seen from the trail. The most spectacular is a climber with a long name and a huge (40 cm diameter and 50 cm length) dark-red flower called Pararistolochia goldieana, which belongs to the family Aristolochiaceae.

The rich biodiversity of the campus is also influenced by its nine lakes. The largest is approximately 70 ha. A dam (The John Craig Dam) was constructed in 1969 and impounds water from the Awba River which runs through the Gunwin watershed. This lake is home to various varieties of fish, aquatic weeds, and birds.

Currently there are many fish in the nine lakes and ponds. Records show that the largest lake was stocked with a wide variety of species. The dominant ones are the African Catfish (Clarias gariepinnus), Nile Perch (Lates niloticus), Slapwater (Heterotes niloticus), and various Tilapines (Oreochromis niloticus, Tilapia zilli, etc.). But a wide variety of other species are present, e.g., Gymnarchus niloticus, Hepsestes odoe, and Channa obscura. There is also a diversity of aquatic weeds, Nuphar spp. (water lily), Azolla sp. (water fern), Potomogeton sp., Typha sp. (bulrush), and Lagarosiphon cordofanus Caspry. L. cordofanus Caspry is uncommon and this may be the only known occurrence in Nigeria (Adeniyi Jayeola, personal communication).

Despite the water and forest habitat, the resident level of mammalian fauna is low. The cane rat or grass-cutter, duiker, mongoose, potto, tree hyrax, civet, and the giant Gambian rat can be seen. Others are the bush-tailed porcupine, squirrels, and small antelopes. Amphibians, lizards, and snakes are also common but have not been studied or documented.

Fruit bats flying over a Ceiba pentandra tree (Yoruba local name: osun papa), IITA. Photo by IITA.
Fruit bats flying over a Ceiba pentandra tree (Yoruba local name: osun papa), IITA. Photo by IITA.

However, there is a large population of straw-colored fruit bats. The flying foxes (Eidolon helvum) form large colonies in the IITA forest. They are the second largest West African bat with a wing span of up to 953 mm. Adults can weigh up to 350 g. They roost conspicuously in the open, covering hectares of treetop branches in the IITA forest and arboretum. An important food for these bats is the fruit of the Iroko tree (M. excelsa). The Iroko produce finger-sized fruits that resemble mulberries. Each fruit contains an average of 80 small, tomato-like seeds which are then transported away from the parent tree. Iroko ranks as one of Africa’s most valuable hardwood trees.

Why is IITA so concerned about its secondary rainforest, indigenous trees, and its rich biodiversity? Deforestation is a serious problem in Nigeria that currently has one of the highest rates of forest loss (3.5%) in the world, translating to an annual loss of 350,000–400,000 ha of forest land (See Ladipo, this issue). Since 1990, Nigeria has lost 6.1 million ha or 35.7% of its forest cover. These figures give Nigeria the dubious distinction of having the highest deforestation rate of natural forest on the planet, and the lowest percentage (2.4%) of rainforest remaining in any African country.

The IITA campus is one of the few reserves in Nigeria where valuable and rare indigenous trees, such as the Iroko, are safe from poachers. Today there is only one specimen of Parkia bicolor in southwestern Nigeria; this one tree is on the IITA campus.

Recently the Director General of IITA, Hartmann, announced that the IITA campus and all it contains will become an African Science Park. This decision is most timely, coming during the International Year of Biodiversity. This will create a more diverse scientific community which could include agriculturalists, ornithologists, lepidopterists, ecologists, foresters, botanists, invasion biologists, and conservationists.

In the future, the IITA campus could be used as a research site for reconciling increasing agricultural production in the tropics and the conservation of biodiversity. IITA has embarked on seed collecting and propagation of indigenous trees to develop an in-situ conservation program for indigenous trees of West Africa. It is also working with scientists at the A.P. Leventis Ornithological Research Institute (APLORI); Centre for Environmental, Renewable, Natural, Resources Management Research and Development (CENRAD); Forestry Research Institute of Nigeria (FRIN); the University of Ibadan; and the Royal Botanical Gardens, Kew to ensure that its rich biodiversity will be conserved for many generations to come. This new initiative at IITA will be used to educate and encourage others in Nigeria to preserve these valuable rainforests.

Hall, J.B. and D.U.U. Okali. 1978. Observer-bias of complex in a floristic survey of tropical vegetation. Journal of Ecology 66: 241–249.

Hall, J.B. and D.U.U. Okali. 1979. A structural and floristic analysis of woody fallow vegetation near Ibadan, Nigeria. Journal of Ecology 67: 321–346.

Unlocking the diversity of yam

IITA scientists inspect yam plants in the field gene bank. Photo by O. Adebayo, IITA.
IITA scientists inspect yam plants in the field gene bank. Photo by O. Adebayo, IITA.

The International Year of Biodiversity (IYB) has emphasized the need for global action that will unravel the genetic diversity of yam, a root crop that provides food security to 300 million people in sub-Saharan Africa.

Yam is grown in about 51 countries in the tropics and subtropics, with yields averaging about 11 t/ha in the major producing countries of West Africa (Nigeria, Cote d’Ivoire, Ghana, and Bénin). However, little is known about the tuber crop’s diversity.

“This aspect is important for yam improvement to meet the demand of people depending on this crop for food and livelihood,” says Ranjana Bhattacharjee, IITA Scientist working on fingerprinting the yam germplasm collection.

Yam provides calories and puts money in the pockets of farmers. The tuber-bearing climbing plant from the genus Dioscorea also plays a major role in sociocultural activities in West Africa including traditional marriages and the New Yam Festival.

Globally, there are over 600 species of yam but only a few are cultivated for food or medicine. Scientists fear that some species are threatened and might become extinct as a result of climate change and genetic erosion. This prompts the calls for conservation.

The major edible species of African origin are white Guinea yam (D. rotundata Poir.), yellow Guinea yam (D. cayenensis Lam.), and trifoliate or bitter yam (D. dumetorum Kunth). Edible species from Asia include water or greater yam (D. alata L.), and lesser yam (D. esculenta [Lour.] Burkill). Cush-cush yam (D. trifida L.) originated from the Americas. White Guinea yam and water yam are the most important in terms of cultivation and use.

Yam tuber. Photo by IITA.
Yam tubers. Photo by IITA.

This preferred staple is usually eaten with sauce directly after boiling, roasting, or frying. The tubers may also be mashed or pounded into dough after boiling, or cooked with sauces and oils. They can be processed into yam balls, chips, and flakes.

Fresh yam tubers are peeled, chipped, dried, and milled into flour that is used in preparing dough called amala (Nigeria) or telibowo (Bénin). Commercial products based on dry flakes or flours from the tuber are produced in Nigeria, Ghana, and Côte d‘Ivoire for export and sale in urban areas.

Though millions depend on the crop, especially in sub-Saharan Africa, not many outside of Africa know about the tuber’s potential for commercialization, and its role in enhancing food security in the region, according to Robert Asiedu, Director of the Program on Root and Tuber Systems at IITA.

“We talk about yam tubers as a food staple of millions of Africans to donors or investors who don’t even know what yam is, how it looks or tastes. So the question is: How would they even think of investing in research in a ‘little-known’ staple like yam?”

Perhaps yam’s low profile in the developed countries or in the West is the major limitation in attracting funding for research, but this hardy tuber is an important “part of man” especially in Africa, the Caribbean, Asia, and the South Pacific Islands where it is widely eaten. According to Asiedu, it is the “preferred and most appreciated staple food and calorie source” in areas where it is grown.

Yam faces constraints that include the high costs of planting material and of labor, decreasing soil fertility, the inadequate yield potential of varieties, and increasing levels of field and storage pests and diseases associated with intensive cultivation.

To tackle some of these constraints, work at IITA for the last few years has focused on improving the tuber, primarily white and yellow Guinea yam, and water yam.

Man with huge yam tuber. Photo by IITA.
Man with huge yam tuber. Photo by IITA.

The breeding program uses the 2,216 accessions of Guinea yam and 816 of water yam in IITA’s genebank to study resistance to anthracnose and virus diseases. Improved populations have been developed with partners in the national agricultural research and extension systems (NARES), who have released varieties in Nigeria (National Root Crops Research Institute, 7) and Ghana (Crops Research Institute, 3).

Despite the success in yam improvement, new challenges keep on coming, prompting researchers to use other tools, such as molecular characterization to unlock the genetic diversity of yam.

Recently, the Global Crop Diversity Trust funded a project in IITA to duplicate, document, and distribute the germplasm of yam to other partners in accordance with the International Treaty on Plant Genetic Resources for Food and Agriculture. Such support is indeed a milestone in yam research. The project also aims to fingerprint the entire germplasm collection at IITA. This will help in understanding the extent of genetic diversity present in the collection. From this, the genes for important traits can be determined through association mapping, a tool that could be used successfully to improve and sustain the crop.

As the world marks the IYB, serious attention from other donors is necessary to keep the crop as a “part of man.”

Safeguarding local varieties ensures food security

Cassava pile after harvest. Photo by IITA.
Cassava pile after harvest. Photo by IITA.

Cassava is a food security crop to more than 600 million people in the developing world, providing incomes to resource-poor farmers, improving their livelihoods, and serving as a buffer against food crises.

The strategic importance of cassava, however, is being threatened, especially in Africa, as local varieties are in danger of disappearing because of genetic erosion and other human and natural factors.

“In Guinea, for instance, about seven local cassava varieties are fast disappearing. This is risky, especially for cassava since it is a clonal crop,” according to Paul Ilona, IITA Senior International Trials Manager. Clonal crops are those propagated through cuttings or other plant parts, not by seeds.

Genetic erosion is a process whereby the already limited gene pool of an endangered species of plant or animal diminishes even more when individuals from the surviving population die out without getting a chance to breed within their endangered low population.

Both local and improved cassava varieties alike create a robust gene pool, offering choices for breeders in future breeding programs. However, the loss of genes from the extinction of some local varieties could limit future improvement programs. The endangered varieties may hold key traits that could offer possible solutions to hunger and poverty in the future.

Woman selling cassava, local market, Nigeria. Photo by IITA.
Woman selling cassava, local market, Nigeria. Photo by IITA.

To prevent the genetic erosion of cassava, IITA and the Institut de Recherche Agronomique de Guinée (IRAG) have stepped up efforts to save native African varieties with the collection of 73 local varieties from Guinea, West Africa.

These varieties are now conserved under ex situ conditions at IITA’s Genetic Resources Center (GRC) in Ibadan, Nigeria. They form part of a collection to safeguard the continent’s plant genetic resources. The collecting mission in that West African country last year was funded by the Global Crop Diversity Trust (GCDT), IRAG-Guinea, and IITA.

“The conservation of local varieties provides hope for future cassava breeding programs and helps to guarantee food security in Africa,” says Dominique Dumet, GRC Head and coordinator of the collecting mission.

Ilona says the loss of native cassava varieties might limit the number of genes available for breeders to work with. “For breeders, any time we lose (crop) genes, it hurts. That is why the conservation of local cassava varieties at GRC is important to us,” he says.

Apart from cassava, the IITA-GRC holds over 25,000 accessions of major African food crops, including cowpea, yam, soybean, bambara nut, maize, and plantain/banana. IITA shares these accessions without restriction for use in research for food and agriculture.

The collecting mission makes Guinea the fourth country, after Angola, Togo, and Bénin, to allow IITA to collect and share their germplasm with other countries, since the International Treaty on Plant Genetic Resources for Food and Agriculture went into force in June 2004.

A tough puzzle: Biodiversity and NRM

Peter Neuenschwander,


In the past, natural resources management covered approximately half of all activities and funds of IITA and similar institutes in the Consultative Group on International Agricultural Research (CGIAR). Most often, it did not include the conservation of wild biodiversity. The other half of funds and personnel were allotted to crop plant biodiversity, mainly the varieties available worldwide in genebanks. Increasingly, however, farmers’ varieties and wild relatives of crop plants became important and the biodiversity of pathogens and witchweed were investigated in view of their use for resistance breeding.

Thanks to new technologies, breeding barriers between species could be overcome and foreign genetic material was incorporated into so-called “genetically modified organisms” (GMOs). These are being tested at a relatively small scale in some African countries. They are the source of real worries and polemical distortions, while countries such as the USA, China, Argentina, Brazil, and India have chosen to grow some GMOs on vast areas. Today, GMOs are at the center of a heated debate in an unnecessarily antagonistic manner, pitting the ideals of biodiversity conservation against the need to feed the world.

Since the end of the 1980s, the importance of biodiversity in general for a sustainable future of Planet Earth has been increasingly publicized. At the Rio Conference in 1990, global warming and the loss of biodiversity were singled out as the two most important issues facing mankind. The climate conference in Copenhagen last year was supposed to reach goals on halting and mitigating climate change. The conference is generally considered to have been a failure; nevertheless, great efforts to avoid a climatic disaster are being taken by many governments, even without the wished-for strict regulations.

And here we are in 2010, the “International Year of Biodiversity”. International nongovernmental organizations such as the International Union for Conservation of Nature (IUCN), BirdLife International, and many others are highly active in conservation and their efforts are showing successes. Most countries have subscribed to their ethics, signed the international treaties, and established focal points for the Convention of Biodiversity. For the CGIAR, though, biodiversity conservation mostly remains germplasm conservation. It is the world leader in the conservation of genetic material of crop plants and their wild relatives (for instance, yam and cowpea, of particular interest in West Africa). It is instrumental in the development of rules and regulations about the ownership of germplasm under the umbrella of the Food and Agriculture Organization.

Meristem excision under aseptic conditions (laminar flow workstation) using stereomicroscope, IITA genebank. Photo by IITA.
Meristem excision under aseptic conditions (laminar flow workstation) using stereomicroscope, IITA genebank. Photo by IITA.

IITA is also co-developing best practices and tool kits for collecting germplasm and houses important pathogen collections. Generally though, conservation of other forms of biodiversity is treated rather timidly. The general antagonism between agriculture and nature conservation thus persists. Yet, it probably need not be so: In 2001, IUCN and Future Harvest came together to publish a policy paper outlining ‘The common ground and common future, how eco-agriculture can help feed the world and save wild biodiversity’. While some of the claims might be overwrought, enough is known to allow progress towards the twin goals of saving the bulk of biodiversity while feeding the human population.

Insects are the majority of all described species. On a worldwide level, BioNET INTERNATIONAL organizes and stimulates the coordination of taxonomic research (of all taxa, but with special emphasis on insects). The IITA biodiversity collection of insects, housed in IITA-Bénin, serves as the network center for West and Central Africa. This collection, the largest in the CGIAR, is instrumental in providing basic information about the biodiversity of natural enemies used in all types of biological control.

In addition, the insectary at IITA-Bénin houses numerous live beneficial insects and mites. IITA-Bénin can respond to the changing situations of ever more invading insects and mites. Thus, in the last few years and in West Africa alone, we have seen the invasion and sometimes the control of spiraling whitefly, a new invading fruit fly (Sri Lanka fruit fly), and very recently the papaya mealybug. Last year, when the cassava mealybug invaded Thailand, IITA was able to provide effective parasitoids without delay.

Many more natural enemies are out there in the wild, suppressing their hosts or their prey. Most concern agricultural pests, but increasingly, conservation biological control is becoming important to save natural habitats from invaders. IITA is participating in these international efforts through its biological control of floating water weeds across Africa.

To assess the elusive so-called “ecosystem services”, sophisticated biodiversity studies are required. IITA’s historic classical biological control projects were against cassava and mango mealybug and cassava green mite, three formidable agricultural pests. The first two were not even known to science before they appeared in new habitats. These examples from South America and India illustrate how the ‘ecosystem services’ provided by pests’ natural enemies in the home environments remain hidden until harmful insects and mites get dissociated from their predators. Important services are also provided by microbials and pollinators, but these become visible to farmers and policymakers only when their function is impaired. Examples are lack of conservation because of wanton destruction or by bad agricultural practices, such as those that lead to the depletion of nutrients in soils or the destruction of suppressive soils.

Researcher monitoring cowpea seeds kept in cold storage room in the IITA genebank. Photo by J. Oliver, IITA.
Researcher monitoring cowpea seeds kept in cold storage room in the IITA genebank. Photo by J. Oliver, IITA.

The contribution to sustainable agriculture and conservation that IITA can make is by improving the tools (GIS, sociological, etc.) and by significant advances in research and its application to real world needs. We can thus establish an intellectual agenda for discussion and change within IITA, collaborating organizations, and society at large. Comparing this claim for action with the actual situation at IITA, we find that traditional biodiversity conservation in the form of crop plant germplasm is rather well implemented; but the conservation of nonplant biodiversity is weakly institutionalized and would need better support. Natural resources management offers the intellectual platform to integrate the different disciplines in a sustainable manner. Unfortunately, the inclusion of all biodiversity activities in a holistic natural resources management remains a dream.

Within the period of 20 years, biodiversity conservation has moved from being a specialized field to becoming an urgent task to be carried out before it is too late and extinction takes away the organisms we might one day have to rely on for survival. Even where we do not completely understand the benefits of biodiversity in providing stability to ecosystems, conservation should be implemented for the good of future generations. Apart from research, this also takes the form of providing refuges for biodiversity for future studies, as is the case with the IITA-Ibadan forest or the rehabilitated forest at Drabo Gbo in Bénin. Our national partners have many more examples; they might cherish our leadership in this matter.