Résumé
A parasitic complex including mealybugs, Dysmicoccus brevipes, induces wilt, a disease found in most pineapple production. The complex includes viruses (PMWaVs, PBCoV and others) transmitted to the plants by the mealybugs. A third element in the complex is different species of ants that establish mutualist interactions with mealybugs, protecting them from their predators and feeding on the honeydew the mealybugs produce. Ants help also spread the mealybugs from plant to plant. In intensive production systems, wilt is mostly controlled by systematic applications of insecticides to eliminate mealybugs and using virus free vitroplants as planting material. Wilt symptoms appear only in the presence of the parasites, viruses and mealybugs. Dysmicoccus brevipes are phloem feeders, they are biotrophic parasites that should be more sensitive to SAR (systemic acquired resistance) than to ISR (induced systemic resistance). SAR was induced against mealybugs with salicylic acid (10-3M, 10ml/plant) on MD2 virus-free vitroplants (50g), after one month of acclimatization in controlled conditions (28°C, 12h photoperiod under Tarentula diodes, 60W). Stimulated plants and unstimulated controls were inoculated with five mealybug larvae per plant (five replicates). Multiplications of mealybugs were evaluated by counting live mealybugs (from young instars as crawlers to adults) after 45 days. SAR was characterized with three molecular markers (AcPAL, AcICS2, AcMYBlike) and three enzymatic markers (PAL, and two PR proteins, βGlucosidase, Chitinase) with five replicates each. Mealybugs multiplication was significantly reduced by an average of 70.3% (p0.05 = 0.045). The effectiveness of SAR was demonstrated by enzymatic and molecular markers that revealed significant differences between treated and untreated plants. SAR is a promising tool to control mealybugs and wilt in more eco-friendly pineapple production systems.