Abstract/Summary

Insects, both as pests and vectors of diseases, are major challenges to cocoa, Theobroma cacao L., production in West Africa. Mealybugs are considered one of the major pests because they vector the cocoa swollen shoot virus, which causes significant losses to cocoa production in the region. The management of cocoa swollen shoot virus disease has been a challenge and strategies put in place to control the disease have had varying success. Therefore, this thesis studied the biology of citrus mealybugs (Planococcus citri) of West African origin and investigated the application of pheromone-baited traps for the management of Pl. citri pests on cocoa farms in Cross River State, Nigeria. A survey was also carried out to determine the knowledge and perception of farmers in the region about how insect pests affect their cocoa farms and their willingness to use the pheromone-baited traps in insect pest management. The biology of Pl. citri of West African origin was discovered to be similar to those of Pl. citri previously recorded from other geographical locations but individuals were smaller in size. The pheromone extracted from this mealybug population was also similar to the commercially available synthetic compound that is currently marketed for the monitoring of Pl. citri in other crops. The pheromone-baited trap experiment showed that Pl. citri was present all year with a peak in April. Traps checked for diel activity pattern showed the greatest male flight activity between 1800-0600. Trap design and colour had no significant effect on the number of male Pl. citri capture whereas trap placement height had a significant effect on the number of Pl. citri caught. The highest number was recorded at 0.3m. Cocoa farmers were aware of the pests affecting their farms and perceived Characoma stictigrapta, Eulophonotus myrmeleon and mirid Sahlbergella singularis to be severe pests of cocoa. Whilst 53.0% of farmers identified mealybugs to be present on their farms, only 4.6% of these farmers considered the damage they cause to be severe and 89.2% were not familiar with the CSSVD. Control by chemical pesticides was the method most commonly used by farmers (81.8%) for insect pest management. Ninety-five percent of the farmers surveyed were not aware of the use of pheromones in insect pest management; however, once the concept of pheromone-based management had been explained to them, the same proportion were willing to use this strategy. The results from this study facilitated recommendations for the development and use of the commercially available Pl. citri pheromone in the integrated pest management of mealybug pests in the region.