The role of flowering plant species in the survival of blackflies (Diptera: Simuliidae) along the lower Orange River, South Africa

Abstract

This study is an investigation of the role that plants play in the survival of adult blackflies by providing shelter and carbohydrate food. A detailed phenological study of the 29 most abundant plant species in the Augrabies Falls National Park showed that throughout the year the percentage of plant species flowering was remarkably constant. It is therefore unlikely that the availability of carbohydrates would limit adult Simulium survival at any time of the year. Blackflies were recorded feeding on the flowers of Pappea capensis. Acacia karroo, A. mellifera, Tamarix usneoides, Ziziphus mucronata, Scholia afra and Sisyndite spartea. An additional survey showed that another 64 plant species flowered throughout the year, and these can be regarded as potential carbohydrate sources. Blackflies were observed sheltering in dense shrubs and trees that provide protection against predation and harsh environmental conditions. This study suggests that vegetated drainage lines are the means by which adult blackflies survive dispersal away from the river. It is concluded that carbohydrate scarcity cannot be considered a limiting factor to adult blackfly survival along the lower Orange River.