Varietal Susceptibility to Sternochetus mangiferae (Fabricius) (Coleoptera: Curculionidae) and Consequences for Mango production in Northern Côte d’Ivoire

In northern Côte d’Ivoire, mango production is significantly hampered by poor fruit quality, largely due to insect pest infestations in orchards. Among these pests, the mango stone weevil (S. mangiferae) is a major cause of internal fruit damage. To support efforts to improve mango quality, a study was conducted from February to July 2023 in the Poro, Bagoué, and Tchologo regions, aiming to identify mango varieties more susceptible to weevil infestation and potentially contributing to its proliferation. Five mango varieties were evaluated- Kent, Keitt, Brooks, Amélie, and the local cultivar known as Lowô. For each variety, five mango fruits were exposed to 20 adult weevils in controlled tubs, with a total of 47 replicates performed (a total of 235 mangoes). Additionally, to assess weevil-induced fruit drop, 10 Amélie mango trees were monitored across six orchards in the three regions. Each week, 200 fallen mangoes were collected along five transects beneath each tree and dissected to detect and quantify internal infestation. Results revealed that the local variety (Lowô) was the least preferred by S. mangiferae, while other varieties showed varying degrees of susceptibility. Weevil-induced fruit drop was closely linked to the fruit’s phenological stage and reached levels as high as 64% in some cases. The findings suggest that promoting less susceptible local varieties and implementing systematic removal of fallen infested fruit could serve as effective integrated pest management strategies. These approaches may contribute to reducing weevil populations and enhancing mango fruit quality in northern Côte d’Ivoire.