Use of pheromone traps as a monitoring tool for the citrus mealybug (Planococcus citri) on cocoa farms

This study developed and optimised a method for the monitoring of populations of P. citri using pheromone-baited traps on cocoa farms and established seasonal activity of P. citri in Cross River State, Nigeria. The effect of time of day, pheromone trap design (Delta and sticky trap), colour (red, blue, yellow, and white) and height placement (0.3. 0.9 and 1.8m) on the capture of adult male P. citri and non-target insects was studied. Planococcus citri was observed to be present year-round with a peak in April, which coincided with the highest air temperatures. By checking traps for diel activity, it was revealed that male flight activity was highest between 1800-0600. Trap design and colour had no significant effect on the number of male P. citri captured, although a smaller number of non-target insects were recorded in Delta traps. Trap height placement had a significant effect on the number of P. citri, and non-target species caught, with the highest number of captures obtained at the lowest trap height (0.3m) and capture rate decreasing as trap height increased. There was a significant positive correlation between the number of trapped male P. citri and air temperature. The results suggest that P. citri is present all year round in the field, that Delta traps are a more suitable trap type, and that 0.3m is an effective height for the monitoring of P. citri on cocoa farms. These findings could be used to improve mealybug monitoring on cocoa farms and could be utilised for the development of an integrated pest management programme.