Control of the Mealybug Vectors of the Swollen Shoot Virus by a Systemic Insecticide

Abstract

DETAILED field and laboratory experiments have been carried out to determine the effect of different systemic insecticides when applied to cacao trees by spraying, tree injection and soil treatment on the mealybugs Pseudococcus njalensis, Laing, and Pseudgcoccus citri, Risso., the main vectors of the swollen shoot virus of cacao. They have shown that CR409, a systemic insecticide containing as main ingredient bisdimethylamino - fluoro - phosphine oxide, gave the best results when applied to the soil directly around the trunk of the trees in a shallow trench at a dosage based on a girth-weight correlation which has been used in all experiments described below. Five hundred trees naturally infested with mealybugs were treated; 10 per cent of the trees, chosen at random, were cut down before and after treatment, the number of all stages of mealybugs on all parts of the tree being counted under a binocular microscope.