Integrated Pest Management


Dr. Tim Grout


Prof. Sean Moore, Dr. Aruna Manrakhan, Dr. Evans Mauda, Dr. Tammy Marsberg, Prof. Hano Maree, Prof. Martin Hill, Prof. Johnnie van den Berg, Dr. Candice Coombes,


Prof. Anne Grobler, Prof. C. Weldon


This programme includes important cosmetic and production pests such as citrus thrips, Scirtothrips aurantii, various mealybug species, bollworm, Helicoverpa armigera, red scale, Aonidiella aurantii and citrus psylla, Trioza erytreae. There is a continuous search for more IPM-compatible means for controlling these pests, such as augmentative releases of natural enemies, entomopathogenic fungi and botanicals. Research on the Asian citrus psyllid, Diaphorina citri, is also being attempted in East Africa in collaboration with research organisations there. This is in proactive anticipation of the movement of the Asian species down the African continent. Research on citrus psylla primarily focuses on alternative control strategies to systemic organophosphates and the taxonomy of close relatives in the genera Trioza and Diaphorina that may be encountered on sticky traps or in surveys. Molecular techniques to identify any immature life stages of insects found in citrus need to be developed in case any of these are considered phytosanitary pests for new markets.

Although mealybugs are considered key pests from a cosmetic and production viewpoint, their phytosanitary threat is most serious and the reliable identification of immature stages is critical for some export markets. Research to evaluate the efficacy of some commercially available natural enemies for mealybugs and red scale is also being conducted in addition to delivery systems for microbial control products. The pest status of mealybugs has increased in orchards grown under nets while other pests appear easier to control in these situations.  Research on IPM of citrus under nets is being conducted in different production regions.

This programme also covers research on Australian bug, leafhoppers, woolly whitefly, leafrollers, citrus flower moth, citrus leafminer, fruit piercing moth and all pest mites. The potential for disrupting the biocontrol of pests and potential pests is also investigated in this programme. Standard bioassay techniques have been developed for five indicator species: (1) Aphytis lingnanensis; (2) Chilocorus nigritus; (3) Euseius citri or Eaddoensis; (4) Trichogrammatoidea cryptophlebiae; (5) Coccidoxenoides perminutus. A database of non-target effects for these natural enemies to most chemicals used in citrus orchards has been developed.