Infestation of African savanna ecosystems by subterranean termites

This review is an analysis of the dimensions of termite infestation in African savannas. The aim of this work is to draw the attention of ecologists, conservationists, policy makers and farmers to the current and future threats of subterranean termites to the functioning and sustainability of such ecosystem habitats. This study analyzes and describes termite problem (questionable changes in density and assemblage structure) in selected African savannah ecosystems, synthesizes information on the effects of various human induced habitat disturbance regimes on termites’ assemblage structure, predators, nests and feed resources to generate hypotheses relating termite infestation with anthropogenic activities; it describes and critiques existing termite management practices. The review is suggestive that the infestation and resultant undesirable effects of subterranean termites in African savannahs are largely a consequence of the inappropriate savannah management practices (overgrazing, indiscriminate tree cutting and overhunting) undertaken by humans in pursuit of various livelihood options. Based on the evidence presented herein, we hypothesized that (1) human induced habitat disturbance in savanna ecosystems alters the feeding group composition of termites’ assemblages, favoring grass harvesters and polyphagus termite feeders that forage on more abundant food items, paying little attention to rarer food items and (2) habitat disturbance through activities like heavy grazing and overhunting results in decline in the populations of both macro and microscopic termite predators, which eventually enhances the proliferation of termite populations, escalates the density of termite nests particularly epigeal mounds and intensifies consumption of herbaceous savannah vegetation. The review calls for dedicated efforts to develop ecological thresholds of savannah biotic and abiotic ecosystem components in which human induced disturbance regimes trigger the destructive behavior of termites. This would provide information that will act as a precautionary savannah habitat monitoring and decision support tool to prevent future infestation of savannah habitats with termites. Also, the review shows that majority of the termite control practices are ineffective, ecologically unsustainable and above all, do not address the root cause of termite infestation and thus merely provide temporary relief to the problem. As such, termite control methods that attempt to enhance proliferation of termite predators need to be studied, developed and emphasized. This review reveals that human induced habitat disturbance depletes termites’ predator populations, leading to proliferation of termite populations particularly grass harvesters that intensify their consumption on grass biomass and eventually contribute to denudation of herbaceous vegetation cover in savannah ecosystems.