Problem Statement: The Omatako Dam is the main large storage dam for the supply of water to towns and cities in central Namibia. Engineers feared that ant and termite activity might affect the structural integrity of its earth ramparts. A non-taxonomist investigated the earth structure, observed some ant and termite activity, and advised the responsible utility company to initiate a control programme. A product was selected on advice from an agricultural pesticide supplier for a quarterly spraying programme to protect the ramparts. Three years later no reduction in ant and termite activity had been observed.

Methods: Following the lack of results from the initial attempts at control, taxonomists from the National Museum of Namibia were consulted regarding the potential termite threats.

Outcomes and Impacts: Expert field investigations revealed no evidence of ant or termite species with the ability to move considerable amounts of soil and potentially affect the structural integrity of the dam; the species present build only superficial nests. In addition, the pesticide being used was formulated to protect seeds, and had not been registered for application on either ants or termites. It was therefore unlikely to be effective when applied as a contact pesticide on the surface for the targeted organisms. The spraying programme, which reportedly cost in excess of US$ 200 000 annually in pesticides alone, was terminated and replaced by annual inspections on wall integrity. Five years later, no discernable deterioration of structural integrity has been observed.

Lessons: Proper surveys need to be carried out by qualified taxonomic personnel. Correct identification needs to be ensured before deciding on a course of action. If action is required, it needs to be ensured that the pesticide is registered for the target organism and that the application procedure will have the desired effect.