Mirid resistance studies in Côte d'Ivoire : Assessment of antixenosis, antibiosis and tolerance

N'Guessan François K., N'Goran Jeanne A.K., Eskes Albertus. 2006. Mirid resistance studies in Côte d'Ivoire : Assessment of antixenosis, antibiosis and tolerance. In : Global approaches to cocoa germplasm utilization and conservation : Final report of the CDC/CCO/IPGRI project on "Cocoa germplasm utilization and conservation: A global approach" (1998-2004). Eskes Albertus (ed.), Efron Yoel (ed.). CFC, ICCO, IPGRI. Amsterdam : CFC, 177-186. (CFC Technical paper, 50) ISBN 978-92-9043-734-5

Résumé : A study was conducted to identify sources of mirid resistance in cocoa. Cocoa clones of diverse origins were evaluated for antixenosis, antibiosis and/or tolerance. Antixenosis assessment was based on the number of feeding lesions on twig segments in a choice test. Antibiosis was measured through survival of young mirid nymphs on shoots and on pods, whereas tolerance was assessed through the reaction of the twigs to fresh mirid feeding punctures. Significant differences (P<0.05) were found between the genotypes tested with regard to antixenosis, antibiosis and tolerance. Clones T79/501, UPA134, ICS60, UPA409, PA150, IMC57, IFC14, N38, R15, IFC6, IFC15, IFC5, EQX3360-3, LCTEEN, EET59, SCA6, PA107 and Playa Alta 2 were the least attractive to mirids. These clones sustained between 2 and 3 lesions compared to the most attractive ones that sustained between 6 and 8 lesions per twig segment. UPA402, T79/501, T60/887 and IMC67 gave the lowest rate of mirid nymph survival, suggesting that they exhibit antibiosis. Antibiosis on pods appeared correlated with antibiosis on twigs. In the tolerance tests, IMC47, PA150, PA107, SCA6 and C151-61 sustained high numbers of feeding lesions, but showed high rates of recovery from lesions, low levels of dieback and/or an ability to regrow after damage, indicating that they are tolerant to mirid damage. Constraints encountered and the need for further improvement of the test methods are discussed. The results of the resistance test confirmed field observations on cumulative mirid damage for some, but not all, clones.

Classification Agris : F30 - Génétique et amélioration des plantes
H10 - Ravageurs des plantes

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

Auteurs et affiliations

• N'Guessan François K., CNRA (CIV)
• N'Goran Jeanne A.K., CNRA (CIV)
• Eskes Albertus, CIRAD-CP-UPR Bioagresseurs de pérennes (FRA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/537710/)

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