Sources de résistance d'Opuntia spp. contre la cochenille à carmin, Dactylopius opuntiae, au Maroc

Sources of resistance of Opuntia spp. against the prickly pear cochineal Dactylopius opuntiae, in MoroccoThis article describes the screening of 248 genotypes of different species of Opuntia spp. for resistance to Dactylopius opuntiae (Hemiptera: Dactylopiidae). This cactus germplasm came from a collection maintained at the National Institute of Agronomic Research (INRA), Morocco. The objective of this research was to identify ecotypes or clones resistant to this cochineal in order to reconstitute the cactus orchards that have been totally devastated in several regions of the kingdom. Natural and artificial infestations from surrounding hedgerows were monitored on a one‐hectare plot planted with 744 cactus plants belonging to these 248 genotypes of Opuntia spp. The design of the experiment was a randomized complete block with three replicates. Data on the evolution of the vegetative state of the cactus plants, as well as their level of infestation with the cochineal, was collected regularly. The results show that only seven ecotypes (Marjana, Belara, Karama, Ghalia, Angad, Cherratia and Melk Zhar) proved to be resistant to the soft scale pest, compared to the rest of the 241 clones that were infested. The seven resistant ecotypes have been registered in the national cactus catalogue and a parcel of mother plants with this identified plant material resistant to D. opuntiae was established. These resistant ecotypes will be the subject of later studies of resistance mechansims (antibiosis and antixenosis) for the cochineal and also for research on genetic improvement of the cactus in Morocco.