Releases of mass reared alien invasive plant biological control agents against aquatic weeds in the Kruger National Park- a worthwhile exercise?

Releases of mass reared alien invasive plant biological control agents against aquatic weeds in the Kruger National Park- a worthwhile exercise?

Des Conlong 1, 2 and Ezekiel Khosa3
1South African Sugarcane Research Institute, 170 Flanders Drive, Mount Edgecombe. 4300. KwaZulu-Natal, South Africa.
2Department of Conservation Ecology and Entomology, Faculty of Agri-Sciences, Stellenbosch University, P.O. Matieland, Stellenbosch. South Africa.
3SAN Parks, Alien Biota Section, Skukuza, Kruger National Park.
;

Since 2010, the South African Sugarcane Research Institute (SASRI) has supplied the Alien Biota section of the South African National Parks (SAN Parks), biological control agents for water lettuce (Pistia stratiotes) and water hyacinth (Eichornia crassipes) control at selected sites in the Kruger National Park. Sites with the former weed included the Sabie river below Lower Sabie Rest Camp in the South, around Skukuza Rest Camp, Orpen Dam, the Letaba river and Dakamila Pans in the north. Neohydronomus affinis exclusively was released at these sites. A mixture of Neochetina bruchi and N. eichhorniae were releases at sites infested with water hyacinth on the Letaba river at Engelhardt Dam and Makhadzi spruit. Initially, the mired Eccritotarsus bethae was also released at Makhadzi spruit.

The numbers of biocontrol agents released at each site over time, and the colonisation and progress of control over the last three years at the various sites will be presented and discussed. At some sites herbicide use has been drastically reduced. A case will be made for regular monitoring of these sites, and the implementation of an integrated pest management approach to minimise costs, and maximise sustainability of the control of these weeds at these sites and others.