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Colby College

Publication Date

Fall 2006

Program Name

Botswana: Ecology and Conservation


The presence of the tsetse fly has historically been an obstacle to the utilization of the resources of the Okavango Delta and the rest of Northern Botswana. In the late 1990’s, an outbreak of trypanosomiasis in cattle, the disease carried by tsetse, prompted the government of Botswana to implement an aerial spraying operation to eradicate the flies. The broad spectrum pesticide deltamethrin was applied over three months in a Northern block of the delta in 2001 and a southern block in 2002. Post-spray monitoring, carried out by the Henry Oppenheimer Okavango Research Center (HOORC), showed that although the pesticide did not severely impact vertebrate species, both aquatic and terrestrial invertebrate populations were negatively affected immediately following the spray. Most populations, however, eventually recovered to pre-spray numbers. In May-August of 2006, the Kwando-Linyanti River System to the northeast of the Delta was sprayed with deltamethrin. As both the abundance and diversity of invertebrates were reduced following spraying in the Delta, a similar result is likely to be seen in the Kwando-Linyanti system. In the present study, preliminary post-spray monitoring of aquatic invertebrates in this system shows that the community structure of aquatic invertebrates in the selected sites following the spray was different from the composition in samples taken before spraying.


Terrestrial and Aquatic Ecology


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