Population dynamics of cocoa [Theobroma cacao] pod borer Acrocercops cramerella: importance of host plant cropping cycle [in Sabah]

The cocoa pod borer was the major insect pest of cocoa in Sabah, East Malaysia. The level of pest attack and the size of the pest population for this species was documented over several cropping seasons in Sabah. The pest population cycles in phase with the crop cycle. One possible reason for this was that since larval survival in the pod was dependent on pod age, the changing age structure of the pod population caused fluctuations in overall larval survival. This was demonstrated using a simple numerical model. The model was then used to investigate the effect of the amplitude of the cropping cycle on the pest population Overall larval survival was lowest when the amplitude of the model crop cycle was greatest. Natural events or management practices that altered the pod population age structure therefore increased or decreased larval survival. Sleeving young pods and the removal of pods from the trees were two control methods that affect the pod population age structure. Correct application of such control methods reduced the pest population