Cassava (Manihot esculenta Crantz) with its long life cycle is affected by several diseases of which cassava bacterial blight (CBB) is the major bacterial disease in the cassava belt worldwide. The epidemiological and ecological investigations undertaken on the disease showed that the causal agent, the bacterium Xanthomonas axonopodis pv. manihotis (Xam), possesses several means for survival and dissemination that may play an important role as inoculum sources for the infection when favorable conditions occur, and the subsequent damage of the plant causing severe yield losses. In fact, Xam survives epiphytically on some weeds occurring in and around cassava fields without developing blight symptoms. Investigating the survival period over the seasons, a longer survival exceeding 5 months has been observed in non-decayed cassava debris. Also, some insects in cassava field like the variegated grasshopper (Zonocerus variegatus) vehicles the pathogen for some time. Over seasons Xam also survives often latently, in cassava stems which are then used for establishing new plantations. In regional disease surveys across ecozones in West Africa, no zone of preference has been found. Though, comparing the development of the disease and the damages caused in yield loss trials in two agro-eco-zones over 2 years, CBB was more pronounced and caused higher yield and biomass losses in the forest savannah transition zone than in the dry savannah where symptom development was positively correlated with the rainfall patterns. The detailed knowledge of the epidemiology, disease development, survival and dissemination, of the reaction of cassava varieties towards CBB such as physiological resistance mechanisms, identification of genetic resistance (QTL) and the background of observed field resistance as well as of the influence of planting time and cropping pattern allows to recommend integrated management measures such as sanitation, intercropping, removal of diseased leaves, management of planting dates according to ecozone, soil amendments, use of resistant genotypes.

Populations of Xanthomonas axonopodis pv. manihotis and X. axonopodis pv. vignicola, causal agents of cassava and cowpea bacterial blight, respectively, were quantified in insects. The pathogens were found in the faeces, the intestines, and on the legs and mandibles of Zonocerus variegatus. Additionally, X. axonopodis pv. manihotis was localized in the insect gut by immunofluorescence microscopy. Xanthomonas axonopodis pv. manihotis survived at least 1 week in the insect intestines and at least 5 weeks in faeces kept under controlled conditions, while survival in faeces exposed to sunlight was <2 weeks. Five percentage [e.g. 5.8 · 10 7 colony-forming units (CFU)/g faeces] of the fed population of X. axonopodis pv. manihotis in cassava leaves were recovered viable in the faeces after passage through the insect. The transmission of cassava bacterial blight by pathogen-contaminated insect faeces to intact, healthy cassava leaves was demonstrated for the first time. Xanthomonas axonopodis pv. vignicola was isolated from organs and faeces of the grasshopper Pyrgomorpha cognata, the Senegalese grasshopper (Oedaleus senegalensis), bee (Apis mellifera) and three Coleoptera (Ootheca mutabilis, Mylabris spp., Exochomus troberti) collected in bacterial blight-infected cowpea fields. Cowpea belonged to the diet of 19 grasshopper species collected in cowpea fields as demonstrated by residues in their faeces. Pathogencontaminated Z. variegatus initiated an epiphytic population of 8.9 · 10 4 CFU/g on healthy cowpea leaves. Spraying cassava and cowpea leaves with 10 2 and 10 4 CFU/ml of their respective pathogen was sufficient to evoke symptoms. A possible role of insects in the transmission of X. axonopodis pvs. vignicola and manihotis is discussed.www.blackwell-synergy.com J. Phytopathology 155, 159-169 (2007) Journal compilation Ó 2007 Blackwell Verlag, Berlin No claim to original US government works 160 Zandjanakou-Tachin et al.

Termites are social insects reported from many countries of the world. Some species of them are known to be beneficial to man, whereas some others cause substantial losses (billions of US dollars annually) of properties and amenities. Various preventive and remedial methods are used to control undesirable termite species. The current review paper gives an overview of beneficial and detrimental activities of termites. Methods of control of undesirable species of termites are given and their advantages and disadvantages are discussed. We emphasized on the use of entomopathogenic nematodes (EPNs) as effective, environmentally safe and sustainable biological control method against termites. Species of EPNs recovered in Africa are documented. Some techniques used to collect termites and to maintain them for experiments and also to propagate, to formulate, to store, and to check for the quality of EPNs for application in the laboratory and in the field are also discussed. The environmental factors affecting the potential of EPNs to control termites are discussed. The information provided in this chapter will help researchers to enhance their skills of the use of EPNs against termites by selecting from the methodologies described here the best ones to adapt to particular experimental conditions, especially in African soil conditions.

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Background: Banana constitutes an important crop in the tropics and participates in food security in many countries of Africa. It is a widely consumed fruit in Benin. Unfortunately, the trend in yields of this crop showed a year to year decrease since 2008 to 2019, leading production to continue falling short of demand. However, there is a paucity of information on farming systems in Benin, an important step to tackle this issue. This study aims at characterizing the types of bananas farming production systems. Methods: We conducted structured interviews with sixty-two (62) farmers in four villages of Houéyogbé District in southern Benin between November 2015 and February 2016. Farmers were selected randomly in each village from lists based on the recommendation of local authorities and extension services officers. Results: The results reveal three classes of banana farms which operate differently and thus have different features. Group 1 is made up of small-scale farms with low-income farmers. These farmers did not hire labour, did not follow agronomic production practices, and did not maintain their farms well. Such farms can be classed as “backyard crop garden”. Group 2 includes farms with average size and income in whose farmers maintain their fields, conduct inter-cropping, did not use bought planting material but sold it. Exclusively headed by men, Group 3 includes large-size banana farms whose owners had high income, who use fertilizer, and maintain their farms well. Areas planted, seed purchase, leaf-stripping and system of production significantly influence income at the 1%, 5% and 10% thresholds respectively. Conclusion: Several constraints to banana production have been identified through this study. They include pests and diseases, lack of clean-certified planting material, type of land, amount of fertilizer and maintenance inputs, and market. In addition, production is limited by a lack of knowledge on agronomic practices. Training on macro-propagation, agronomic practices, pests and diseases recognition with control strategy could help overcome these constraints and improve banana production in this district.