Work

Detection, Survival and Transmission of Xanthomonas axonopodis pv. manihotis and X. axonopodis pv. vignicola, Causal Agents of Cassava and Cowpea Bacterial Blight, respectively, in/by Insect Vectors

Year: 2007

Type: article

Abstract: 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 Zonocerusvariegatus. 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 × 107 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. Pathogen‐contaminated Z. variegatus initiated an epiphytic population of 8.9 × 104 CFU/g on healthy cowpea leaves. Spraying cassava and cowpea leaves with 102 and 104 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.

Source: Journal of Phytopathology

DOI: 10.1111/j.1439-0434.2007.01210.x

Authors: M. Zandjanakou‐Tachin, A. Fanou, P. Le Gall, K. Wydra

Institutions: Leibniz University Hannover, International Institute of Tropical Agriculture

Language: English

Topic: Plant Pathogenic Bacteria Studies

Subfield: Plant Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Zero hunger

Open Access status: bronze

Funders: Deutscher Akademischer Austauschdienst, Bundesministerium für Wirtschaftliche Zusammenarbeit und Entwicklung