Influence of soil properties on pre-pupal burrowing, pupation and nutritional content of Gonimbrasia belina Westwood

Mopane worms (Gonimbrasia belina) are important sources of nutrition among many people in southern Africa. Threats of climate change and over-harvesting have provided compelling evidence to conserve and domesticate these edible insects through a better understanding of their natural habitat. A study was conducted in Zimbabwe, with the objectives of determining the influence of soil properties on mopane larvae habitation and its nutritional content. Field sampling was conducted in treatment (with known mopane worm occurrence) and control (without mopane worm) sites. Soil and leaf samples were taken from each site and analysed for selected physical and chemical properties. Data were analysed using detrended correspondence analysis and Student t-test. Results show that G. belina larval abundance was highest on trees rooted in soils with 80–97% sand. Pupae population was positively linked to soil organic matter content, litter content, and exchangeable Ca, Mg and K concentrations but negatively linked to soil bulk density. The concentrations of Mg and K in the mopane tree leaves and mopane worm were at least seven times that of soil. Protein (55.6% DM) and fat (18.5% DM) were relatively higher in mopane worm than foliar samples. From these results, it can be hypothesised that the nutritional composition of the leaves had no link in habituating mopane worms. We conclude that mopane worms are more likely to burrow and metamorphosise to pupae into less compacted sandy soils with relatively high content of organic matter and litter content.