The witchweed striga gesnerioides and the cultivated cowpea: A geographical and historical analysis of their West African distribution points to the prevalence of agro-ecological factors and the parasite's multilocal evolution potential

Sadda Abou-Soufianou, Coppens D'Eeckenbrugge Geo, Saidou Abdoul-Aziz, Diouf Abdoulaye, Salifou Jangorzo Nouhou, Issoufou Hassane Bil-Assanou, Malam-Issa Oumarou. 2021. The witchweed striga gesnerioides and the cultivated cowpea: A geographical and historical analysis of their West African distribution points to the prevalence of agro-ecological factors and the parasite's multilocal evolution potential. PloS One, 16 (8):e0254803, 22 p.

Url - jeu de données - Entrepôt autre : https://figshare.com/articles/journal_contribution/Statistics_on_data_collation_S1A_GBIF_data_cleaning_S1B_and_final_data_selection_S1C_/15107239

Quartile : Q2, Sujet : MULTIDISCIPLINARY SCIENCES

Liste HCERES des revues (en SHS) : oui

Thème(s) HCERES des revues (en SHS) : Psychologie-éthologie-ergonomie; Staps

Résumé : The increasing severity of Striga gesnerioides attacks on cowpea across West Africa has been related to its prolificity, seed mobility and longevity, and adaptation to aridity, in a context of agricultural intensification. To understand this fast extension, we analyzed (1) the distributions of the crop and the witchweed with ecological niche modeling and multivariate climate analysis, and (2) the chronological information available from collections and the literature. The ecoclimatic envelope of S. gesnerioides attacks on cowpea is the same as on wild hosts. Consistently, the modeled distribution of cowpea infestations is closely similar to the simple superposition of the parasite model (involving all hosts) and the crop model. Striga gesnerioides infestations are restricted to the driest component of the cultivated cowpea ecoclimatic niche, corresponding to the Sahelian and Sudano-Sahelian belts and the Dahomey gap. Thus, the parasite distribution, determined by its own requirements, does not constrain cowpea cultivation under Guinean climates. The spatial and temporal distributions of S. gesnerioides field infestations are consistent with an earlier impact on cowpea production in eastern West Africa, related itself to a similar trend in cowpea cultivation intensification from Niger, Nigeria and Benin to Burkina Faso and Ghana. Mali and Senegal were affected later, and literature reports of Senegalese strains of S. gesnerioides from the wild developing virulence on cowpea offer a model for the diffusion of witchweed parasitism by multilocal evolution, through host-driven selection, instead of epidemic diffusion. A contrario, in Côte d'Ivoire, cowpea is much less widespread, so the parasite has remained confined to the wild compartment. Thus, both historical and ecogeographic analyses refute the vision of S. gesnerioides as an invader. Instead, they point to the increasing importance and intensification of the crop, and the consequent loss of biodiversity, as the main drivers of the extension and diversification of its crop-specific strains.

Mots-clés Agrovoc : plante parasite, parasitisme, distribution géographique, Striga gesnerioides, Vigna unguiculata, modélisation

Mots-clés géographiques Agrovoc : Afrique occidentale, Cameroun, Niger, Nigéria, Bénin, Togo, Burkina Faso, Mali, Ghana, Côte d'Ivoire, Libéria, Sierra Leone, Guinée, Guinée-Bissau, Gambie, Sénégal

Mots-clés complémentaires : Niche écologique

Mots-clés libres : Striga gesnerioides, Vigna unguiculata, West Africa, Ecological niche modeling, Host driven selection

Classification Agris : H60 - Mauvaises herbes et désherbage
H50 - Troubles divers des plantes

Champ stratégique Cirad : CTS 4 (2019-) - Santé des plantes, des animaux et des écosystèmes

Auteurs et affiliations

• Sadda Abou-Soufianou, Université Dan Dicko Dankoulodo de Maradi (NER)
• Coppens D'Eeckenbrugge Geo, CIRAD-BIOS-UMR AGAP (FRA) ORCID: 0000-0002-1970-0627 - auteur correspondant
• Saidou Abdoul-Aziz, CIRAD-BIOS-UMR AGAP (FRA) ORCID: 0000-0002-1215-6075
• Diouf Abdoulaye, Université Dan Dicko Dankoulodo de Maradi (NER)
• Salifou Jangorzo Nouhou, Université Dan Dicko Dankoulodo de Maradi (NER)
• Issoufou Hassane Bil-Assanou, Université Dan Dicko Dankoulodo de Maradi (NER)
• Malam-Issa Oumarou, IRD (NER)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/599027/)

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