Biological Control of Eldana saccharina Walker in South African Sugarcane: Constraints Identified From 15 Years of Research

Abstract

The progress of the South African Sugar Association Experiment Station’s 15-year-old biological control programme against Eldana saccharina Walker is reviewed. Two approaches at controlling this borer, a ‘new association’ and a ‘modified’ classical biological approach are summarised. Constraints identified as limiting the successful establishment of 10 egg, 12 larval and 2 pupal ‘new association’ parasitoids include host incompatibility, climatic incompatibility, poor ecological and biological life history knowledge, incorrect parasitoid searching ability and hyperparasitic tendencies. The 3 egg and 7 larval ‘modified’ classical biocontrol parasitoids which could be reared in the laboratory had constraints such as parasitising ability, different host habitat, differing host behaviours in different habitats and initial host identification difficulties to overcome. Difficulties encountered in this biological control programme against an indigenous pest insect show that biological control is not easy. Knowledge of constraints identified during this programme will hopefully be of use to others embarking on similar projects.