Resistance of cactus pear clones (Opuntia spp.) to Dactylopius opuntiae: pomological and phenological characterization

Dactylopius opuntiae is a pest that threatens cactus pear cultivation worldwide. In Morocco, thousands of hectares have been completely destroyed since its introduction in 2014. The use of resistant ecotypes remains the most effective strategy to safeguard cactus cultivation at the national scale. The objective of the present study was to evaluate, under greenhouse conditions over a 45-day period, the resistance of 11 cactus pear ecotypes, as well as to perform pomological and phenological characterization of these clones. The results showed a very high level of resistance in ecotype 54, with 0% infestation by adult females. This ecotype prevented the development of cactus cochineal larvae into the adult stage, whereas the other ecotypes allowed the establishment of adult female colonies with infestation rates not exceeding 25%. In contrast, ecotype 149 was found to be highly susceptible. Analysis of colonization dynamics using an exponential growth model confirmed these results. However, clones 10, 11, 14, 19, 27, 28, and 34 exhibited rapid population growth of D. opuntiae, with multiplication factors close to those observed in ecotype 149 and the susceptible control. Pomological characterization revealed that clone 54 exhibited low pomological performance, whereas the ten other tested clones showed medium to high pomological profiles. Phenological monitoring indicated that clones 14, 18, 27, 28, 29, 34, 54 and 149 were characterized by fruit maturity occurring from late July to mid-August. In contrast, clones 10 and 11 were late-maturing, with fruit maturity beginning in mid-September.