STUDIES ON MACADAMIA NUT BORER (CRYPTOPHLEBIA SPP) IN NORTHERN MALAWI

In work on macadamia nut borer (Cryptophlebia batrachopa and C. leucotreta) in the north of Malawi, trap rounds for 6 years showed that peak populations of the moth occurred when the crop is most susceptible to attack, and that the populations at that time are more consistently high. The proportion of C. batrachopa in the catch increased from about 15% in the early years to about 50% in recent years. In trials to reduce the amount of cypermethrin needed for control of borer, and to investigate the use of artificial female sex pheromone in reducing damage, it was found that the minimum effective application rate for cypermethrin was 0.01 % a.i. Three applications of this, followed by three applications of 0.1% a.i. fenitrothion, brought about satisfactory control of borer and bugs. The pheromone of C. leucotreta alone resulted in lower damage rates than did C. batrachopa pheromone alone. Dispenser applications of both pheromones showed more promise for economic control than did dispersed microcapsule applications. © 1990 Taylor and Francis Ltd.