Modelling the Suitable Habitat of Gonimbrasia belina, a Communally Exploited Edible Insect, in Southern African Mopane (Colophospermum mopane) Savannah

Abstract

The mopane worm (caterpillar stage of Gonimbrasia belina), a communally exploited edible insect, is a crucial component in the savanna ecosystems. Harvesting remains informal, largely unregulated, and mostly on communal and private land. Recent increases in demand have raised concerns about sustainability. This study takes the initial step toward developing sustainable harvest strategies by quantifying suitable habitat, estimating each country's contribution to total suitable habitat, estimating the effectiveness of protected areas to capture suitable habitat, and exploring predictor variables affecting the suitable habitat of mopane worms. We employed presence-only modelling to develop an ensemble model that combines generalised additive models (GAM), maximum entropy (MaxEnt), and random forests (RF), resulting in both a full and a restricted ensemble model. The restricted model was constrained to the southern African mopane savannah (Colophospermum mopane) to evaluate potential populations that can sustain harvest within mopane savannah. The full and restricted ensemble models classified 15.1% and 40% of the model landscape as suitable for mopane worms, respectively. Under the restricted model, Zimbabwe contributed 26.8% to the suitable habitat, followed by Botswana (25.3%), South Africa (15.4%), Namibia (14.7%) and Mozambique (11.1%). A total of 36.2% of the suitable habitat fell within protected areas, while the remaining 63.2% fell in non-protected areas. We conclude that local communities, governments and regional conservation authorities should address the harvest management of this communally exploited edible insect.