Systems approaches to innovation in pest management: reflections and lessons learned from an integrated research program on parasitic weeds in rice

This paper provides a retrospective look at a systems-oriented research program, on the increasing occurrence of parasitic weeds in rainfed rice in sub-Saharan Africa, to qualitatively assess merits and identify challenges of such approach. We gained a broad contextual overview of the problem and different stakeholders' roles, which enabled identification of entry points for innovations in parasitic weed management. At the crop level parasitic weed infestation is associated with poor soil fertility and water management. Farmers' infrequent use of inputs to control them was caused by various factors, ranging from fears of undesired side effects (agronomic) to a lack of quality control of products (institutional). Furthermore, there may be enough extension agents, but they lack the required training on (parasitic) weed management to provide farmers with advice, while their organizations do not provide them with the necessary means for farm visits. At even higher organizational levels we observed a lack of coherent policies on parasitic weed control and implementation of them. Merits and challenges of an integrated multi-stakeholder and multi-level research project are discussed

Indigenous cowpea production and protection practices in Benin

A survey involving more than 129 farmers was carried out in 1998 and 1999 in Ouémé, Benin, to investigate the importance of pests and diseases as constraints to cowpea (Vigna unguiculata (L.) Walp.) production. Results indicated that in the Ouémé valley Sclerotium rolfsii Sacc. and Aphis craccivora Koch are specific concerns. Weeds such as Justicia anselliana (Nees) T. Anders, Ipomoea aquatica Forsskal and Commelina erecta L. were also reported as being troublesome. On the Ouémé plateau Imperata cylindrica L. Beauv. was reported to be a major weed. Callosobruchus maculatus Fab. and Bruchidius atrolineatus Fab. may cause up to 100% loss within a few months in storage. Birds and rodents were also reported. In certain areas on the plateau, farmers have developed pest control methods based on indigenous knowledge. In the valley the population density of Eichhorniacrassipes (Mart) Solms. during flooding is used by farmers to predict aphid infestation. A number of plant species used to protect cowpea were reported. In Gbékandji village, natural enemies such as Rhabdepyris sp., Evania sp., and Chelonus sp., were observed. They were rare in the valley, where farmers rely on chemical control. Farmers reported alternative hosts of cowpea pests from the families Fabaceae (eight species), Mimosaceae (two species), Ceasalpiniaceae (five species), Capparidaceae (two species) and Pontederiaceae (one species). Based on the hierarchy of constraints, sustainable integrated pest management technologies are being developed with farmers using a participatory approach. RÉSUMÉ Bien que des options de lutte existent, les ravageurs et les maladies demeurent la principale contrainte à la production du niébé (Vigna unguiculata (L.) Walp.). Les problèmes phytosanitaires du niébé ont fait l'objet d'enquêtes menées en 1998 et 1999 auprès de plus de 129 paysans dans la vallée et sur le plateau du département de l'Ouémé au Sud Bénin. Les résultats montrent que dans la vallée, Sclerotium rolfsii Sacc. et Aphis craccivora Kock sont des préoccupations spécifiques. Les mauvaises herbes: Justicia anselliana (Nees) T. Anders, Ipomoea aquatica Forsskal et Commelina erecta L. y sont préoccupantes. Imperata cylindrica L. Beauv. est la plus nuisible sur le plateau. Callosobruchus maculatus Fab. et Bruchidius atrolineatus Fab. peuvent occasionner 100% de perte en quelques mois de stockage. Les oiseaux et les rongeurs ont été signalés. Dans certaines zones du plateau, des paysans ont développé des méthodes de protection basées sur des connaissances endogènes. Selon les paysans de la vallée, la densité de peuplement d'Eichhornia crassipes (Mart) Solms. pendant l'inondation permet de prédire l'infestation de pucerons. Des plantes à effet insecticide ont été signalées. Dans le village de Gbékandji, des ennemis naturels: Rhabdepyris sp., Evania sp., et Chelonus sp., etc. ont été observés. Ils étaient rares dans la vallée où l'utilisation de produits chimiques est prononcée. Les paysans ont rapporté des hôtes alternatifs des déprédateurs de niébé de la famille des Fabaceae (08 espèces), Mimosaceae (02 espèces), Ceasalpiniaceae (05 espèces), Capparidaceae (02 espèces) et Pontederiaceae (01 espèce). Se basant sur la hiérarchisation des contraintes, des méthodes participatives de mise au point de technologies durables de lutte intégrée sont en cours d'élaboration

Rhamphicarpa fistulosa, a parasitic weed threatening rain-fed lowland rice production in sub-Saharan Africa – A case study from Benin

Expansion of the facultative parasitic plant Rhamphicarpa fistulosa as a weed of rain-fed lowland rice was studied in 2007 on a national level (Benin) by repeating a survey from 1998. Wider species’ distribution was investigated in 2008. Current and potential impact and management strategies were investigated through farmer surveys and pot experiments. Out of 36 cultivated inland valleys visited across Benin, eight were found to be infested with Rhamphicarpa. Out of nine inland valleys inspected in 1998, Rhamphicarpa was found in five in 2007, compared with only three in 1998. Farmers estimated Rhamphicarpa-inflicted yield losses could exceed 60% and indicated that heavily infested fields are abandoned. In a pot experiment with a wide infestation range, the popular cultivar Gambiaka, combining resistance with sensitivity, showed a mean relative yield loss (RYL) of 63%. Parasitic Rhamphicarpa biomass (PRB), the difference between the above-ground biomass produced with and without a host, was suggested as indicator for infection level of this facultative parasite and hence as a practical measure for host resistance. Genetic variation in resistance and tolerance levels was observed among rice cultivars, but fertilizer applications significantly reduced parasite numbers, biomass and effects, cancelling out such genotypic differences. Depending on the tolerance level of the cultivars, the PRB only accounted for 3.7–38.8% of the average parasite-inflicted host biomass reductions, indicating phytotoxic effects of Rhamphicarpa infection. R. fistulosa is an apparently increasing constraint to rain-fed lowland rice in Benin, threatening rice production in the wider region. The use of resistant and tolerant cultivars, combined with fertilizer applications could reduce Rhamphicarpa infections and mitigate negative effects on rice yields

Indigenous cowpea production and protection practices in Benin

A survey involving more than 129 farmers was carried out in 1998 and 1999 in Ouémé, Benin, to investigate the importance of pests and diseases as constraints to cowpea (Vigna unguiculata (L.) Walp.) production. Results indicated that in the Ouémé valley Sclerotium rolfsii Sacc. and Aphis craccivora Koch are specific concerns. Weeds such as Justicia anselliana (Nees) T. Anders, Ipomoea aquatica Forsskal and Commelina erecta L. were also reported as being troublesome. On the Ouémé plateau Imperata cylindrica L. Beauv. was reported to be a major weed. Callosobruchus maculatus Fab. and Bruchidius atrolineatus Fab. may cause up to 100% loss within a few months in storage. Birds and rodents were also reported. In certain areas on the plateau, farmers have developed pest control methods based on indigenous knowledge. In the valley the population density of Eichhorniacrassipes (Mart) Solms. during flooding is used by farmers to predict aphid infestation. A number of plant species used to protect cowpea were reported. In Gbékandji village, natural enemies such as Rhabdepyris sp., Evania sp., and Chelonus sp., were observed. They were rare in the valley, where farmers rely on chemical control. Farmers reported alternative hosts of cowpea pests from the families Fabaceae (eight species), Mimosaceae (two species), Ceasalpiniaceae (five species), Capparidaceae (two species) and Pontederiaceae (one species). Based on the hierarchy of constraints, sustainable integrated pest management technologies are being developed with farmers using a participatory approach. RÉSUMÉ Bien que des options de lutte existent, les ravageurs et les maladies demeurent la principale contrainte à la production du niébé (Vigna unguiculata (L.) Walp.). Les problèmes phytosanitaires du niébé ont fait l'objet d'enquêtes menées en 1998 et 1999 auprès de plus de 129 paysans dans la vallée et sur le plateau du département de l'Ouémé au Sud Bénin. Les résultats montrent que dans la vallée, Sclerotium rolfsii Sacc. et Aphis craccivora Kock sont des préoccupations spécifiques. Les mauvaises herbes: Justicia anselliana (Nees) T. Anders, Ipomoea aquatica Forsskal et Commelina erecta L. y sont préoccupantes. Imperata cylindrica L. Beauv. est la plus nuisible sur le plateau. Callosobruchus maculatus Fab. et Bruchidius atrolineatus Fab. peuvent occasionner 100% de perte en quelques mois de stockage. Les oiseaux et les rongeurs ont été signalés. Dans certaines zones du plateau, des paysans ont développé des méthodes de protection basées sur des connaissances endogènes. Selon les paysans de la vallée, la densité de peuplement d'Eichhornia crassipes (Mart) Solms. pendant l'inondation permet de prédire l'infestation de pucerons. Des plantes à effet insecticide ont été signalées. Dans le village de Gbékandji, des ennemis naturels: Rhabdepyris sp., Evania sp., et Chelonus sp., etc. ont été observés. Ils étaient rares dans la vallée où l'utilisation de produits chimiques est prononcée. Les paysans ont rapporté des hôtes alternatifs des déprédateurs de niébé de la famille des Fabaceae (08 espèces), Mimosaceae (02 espèces), Ceasalpiniaceae (05 espèces), Capparidaceae (02 espèces) et Pontederiaceae (01 espèce). Se basant sur la hiérarchisation des contraintes, des méthodes participatives de mise au point de technologies durables de lutte intégrée sont en cours d'élaboration