Heavy Metal Concentrations in Two Populations of Mopane Worms (Imbrasia belina) in the Kruger National Park Pose a Potential Human Health Risk

Abstract

Metal concentrations in Mopane worms from Phalaborwa and Shangoni sites in the Kruger National Park were determined. Metal concentrations were evaluated by inductively coupled plasma optical emission spectroscopy (ICP-OES) and ICP-MS spectrometry after microwave digestion. The results indicate a substantial bioaccumulation of metals in Mopane worms. In Phalaborwa Cd concentrations were 15 times and Cu two times higher than the EU and UK recommended legal limits for human consumption, Zn levels were tolerable. Likewise, Cd, Cu and Zn concentrations at the Shangoni site were 26, 2.5 and 0.4 times over the EU and UK approved limits. Manganese concentrations were 20 and 67 times higher than FDA standards respectively. During the study the condition factor of the worms was determined. No significant difference between the condition factors indicated the worms at both sites are in similar condition. Potential sources of metals in the worms are either from the food they eat or pollution settling on the leaves.

Trace Metals, Crude Protein, and TGA-FTIR Analysis of Evolved Gas Products in the Thermal Decomposition of Roasted Mopane Worms, Sweet Corn, and Peanuts

“…The concentration of toxic metals in the plant leaves on which mopane worms were extracted from was compared to those obtained from mopane worms, and substantial bioaccumulation of Cd, Cu, Co, and Mn in mopane worms was reported. The samples were collected from the Kruger National Park in the Limpopo Province of South Africa, and the highest concentrations of Cd, Cu, Co, and Mn were 4.02, 47.73, 4.52, and 3.37 μ g g −1 , respectively, and all these values were above the recommended guidelines by the European Union [ 49 ]. However, in the current study, the concentrations of metals were well below detection limits and we can conclude that the consumption of mopane worms remains safe from potential metal contamination, while concentrations of As in sweet corn should be of serious concern.…”

Safety of Alternative Proteins: Technological, Environmental and Regulatory Aspects of Cultured Meat, Plant-Based Meat, Insect Protein and Single-Cell Protein

“…Greenfield, Akala and van der Bank detected high concentrations of heavy metals in Mopane worms (Imbrasia belina) taken from two sites at a South African national park: cadmium, copper and zinc concentrations were respectively 15-21, 2-2.5 and 0.4 times higher than the recommended legal levels in the United Kingdom and European Union [137]. The concentration of manganese in I. belina was 20-67 times higher than the food safety standard set by the United States Food and Drug Administration [137]. Others found that contaminated feeds led to the accumulation of cadmium, lead or arsenic in soldier fly larvae (Hermetia illucens) and yellow mealworms (T. molitor) [123,138], with one study also suggesting that the accumulation rate was dependent on the insect species and type of metal present [138].…”

“…Vijver et al reported that cadmium, copper, lead and zinc present in soils (naturally or artificially contaminated) were retained in the body of T. molitor, with the extent of accumulation depending on the type of soil and metal [136]. Greenfield, Akala and van der Bank detected high concentrations of heavy metals in Mopane worms (Imbrasia belina) taken from two sites at a South African national park: cadmium, copper and zinc concentrations were respectively 15-21, 2-2.5 and 0.4 times higher than the recommended legal levels in the United Kingdom and European Union [137]. The concentration of manganese in I. belina was 20-67 times higher than the food safety standard set by the United States Food and Drug Administration [137].…”

Nutritional Composition, Health Benefits, and Application Value of Edible Insects: A Review

“…The data showed that the amount of manganese in wild termites was 50–100 times higher than the concentration detected in other insects. From a safety point of view, wild insects may have excessive levels of heavy metals due to the complex and harsh growing environment [ 247 ]. This is not good for insects as a food source.…”