Effect of Fertilizer Application on Mealybug Infestation and Physiological Responses of Cocoa at the CNRA Station, Divo, Côte d'Ivoire

Applying fertilizer is one solution for improving cocoa production. However, while it improves cocoa productivity, it also promotes the development of pests and disease vectors. This study aimed to understand the effects of fertilizer on the proliferation of mealybugs known as vectors of cocoa swollen shoot virus. The experimental design was a Fisher block with four fertilizer formulations (T1 to T4) and an unfertilized control (T0), each replicated three times. Each elementary plot contained 45 cocoa trees from CNRA research station in Divo, Côte d’Ivoire. Mealybug infestation levels were evaluated every 15 days for one year, and three cocoa leaves were collected per treatment and replication in order to determine physiological and biochemical parameters. The data were analyzed using SAS 9.4 and XLSTAT 2025. The results revealed seven species of mealybugs in the treatments: Formicococcus njalensis , Planococcus citri , Ferrisia virgata , Pseudococcus longispinus , Phenacoccus har greavesi , Dysmicoccus brevipes , and Planococcus kenyae . Furthermore, analysis of variance revealed significant differences among the treatments regarding the content of chlorophyll A and B, total chlorophyll, carotenoids, protein, phenolic compounds, and proline. However, among the seven mealybug species identified, principal component analysis revealed a link between Formicococcus njalensis , Ferrisia virgata , and Dysmicoccus brevipes , as well as chlorophyll A and B, total chlorophyll, carotenoids, protein, phenolic compounds, and total sugars, in T0, T3, and T4. Meanwhile, the mealybug species Pseudococcus longispinus and Phenacoccus hargreavesi were linked to proline in treatment T2. Overall, the study showed that fertilizer has a small impact on mealybug and more on the physiological and biochemical parameters.