Xylosandrus crassiusculus (Motschulsky) on Cocoa Pods (Theobroma cacao L.): Matter of Bugs and Fungi

Abstract

Exudation of mucilage from pinhead-sized boreholes in cocoa pods was recorded in Karnataka, India, during 2021. Further investigations showed the association of scolytine beetles with infested pods. The identity of the pest, <i>Xylosandrus crassiusculus</i>, was confirmed through morphological characterization and sequencing of the mitochondrial <i>COI</i> gene. We studied the predisposing factors for its infestation, visible and concealed damaging symptoms, and fungal symbionts. In addition to its well-known symbiotic fungus, <i>Ambrosiella roeperi</i>, a new association of yeast, <i>Ambrosiozyma monospora,</i> was discovered. We also traced the possible role of the mirid bug, <i>Helopeltis theivora,</i> in host selection by <i>X. crassiusculus</i>. Overall results indicated that a 'mirid bug-ambrosia beetle-pathogen complex' is responsible for the severe damage to cocoa pods in South India.