The longhorn grasshopper, Ruspolia differens (Serville), plays an important role as a food source across Sub-Saharan Africa, where it is consumed as a delicacy in both rural and urban areas. The effect of two drying methods (freeze-drying and oven-drying), employed after blanching, on the proximate, fatty acid and mineral composition of the two most common morphs was determined. Ruspolia differens grasshoppers were harvested in Uganda and Kenya from wild swarms during the rainy periods of November–December 2016. Based on cuticular coloration, we identified three morphs, green, brown and purple, which occurred at a ratio of 65:33:2, respectively. Results indicated that these insects have a high lipid content of 36%, as well as significant protein levels ranging between 33% and 46% dry matter. Oleic acid (44%) and palmitic acid (28%) were the two most abundant fatty acids; while the presence of arachidonic acid (0.6%) and docosahexaenoic acid (0.21%) suggests that Ruspolia differens is also a source of polyunsaturated fatty acids. The observed amino acid profile showed similar trends in all morphs, and all essential amino acids were present. Calcium (896–1035 mg/100 g), potassium (779–816 mg/100 g) and phosphorus (652–685 mg/100 g) were quite high among the minerals. The presence of the trace elements iron (217–220 mg/100 g), zinc (14.2–14.6 mg/100 g), manganese (7.4–8.3 mg/100 g) and copper (1.66 mg/100 g) suggests that inclusion of these grasshoppers in human diets may aid in combatting micronutrient deficiencies. Oven-drying Ruspolia differens delivered the same nutritional quality as freeze-drying. Hence, both drying approaches can be adequately used to formulate insect-based food products without noticeable nutritional changes.

Edible orthopterans (grasshoppers, crickets, and locusts) are major delicacies, especially across sub-Saharan Africa. Their promotion as food ingredients is increasingly gaining momentum. This study evaluates the nutritional profiles of three widely consumed orthopterans: Gryllus bimaculatus, Locusta migratoria, and Schistocerca gregaria after blanching and oven-drying. All three species had high protein (65.3, 54.2, and 61.4% on a dry matter (DM) basis for G. bimaculatus, L. migratoria, and S. gregaria, respectively) and fat contents. Oleic (22.9–40.8%) and palmitic (26.1–43.0%) were the two most abundant fatty acids. All essential amino acids (in mg/100 g protein) were present, with glutamic acid (120–131), alanine (90.2–123), and leucine (82.3–84.6) being the most abundant. The minerals (in mg/100 g dry matter) potassium (796–1309) and phosphorus (697–968) were moderately high, and iron (4.60–7.31), zinc (12.7–24.9), manganese (0.40–7.15), and copper (1.20–4.86) were also observed in the samples. Vitamin B₁₂ contents were high (0.22–1.35 µg/100 g dry matter). Our findings demonstrate that the excellent nutritional profile of the three processed insects could serve as promising alternative ingredients for improving food and nutritional security.

The tettigoniid,Ruspolia differens, is a widely consumed grasshopper across Sub Sahara Africa (SSA), mainly where periodic large swarms occur during the rainy months. The present wild harvesting of this grasshopper species is not sustainable and limits the yearlong presence of these delicacies. One method to circumvent this is developing mass-rearing technologies for this nocturnal and omnivorous insect within SSA. However, to mass-rear this species on a large scale, the optimal diets and light regimes need to be established. Complete nutritional profiles of edible insect diets are rare. In our study, using a newly formulated artificial diet we assessed multiple performance traits forR. differens reared at two light regimes. A complete dark (<1 h light, 5:95 L:D) and 50% light (~12 h light, 50:50 L:D) from newly hatched nymphs to death of the adults. Proximate composition of this novel artificial diet was carbohydrates: 53.5%, crude protein: 21.0%, ash: 7.0%, fat: 5.0%, crude fibre: 4.5%. All essential amino acids and mineral elements were also present. It took on average 8-9 moults to reach adults in the light-reared insects as opposed to 6-7 moults for those reared in the dark. Adult longevity in the dark-reared insects was also significantly longer (37±3.7 days) compared to the light-reared ones (10±3 days). These findings strongly support the nocturnal behaviour of these bush crickets and suggest rearing them in a predominantly dark environment would seem a profitable venture, as fewer energy demands in terms of lighting are required. Such a diet, when fully optimised will facilitate automation and reduce labour for feeding them in mass-rearing programs.

Edible bush cricketsRuspolia differens have received considerable interest in recent years primarily due to their widespread consumption across Sub Sahara Africa. Currently, these pseudo grasshoppers are only available in large quantities twice a year during the rainy seasons. Therefore, there is great research interest in studying their farming potential for possible mass rearing. However, due to their cannibalistic behaviours, such attempts have proven an uphill task. This study evaluated measures that may reduce cannibalism by providing alternative prey to rearedR. differens. Ten young adults of either females or malesR. differens were kept separately in well-aerated cages (50×50×50 cm). Then, two sets of experiment were set up as follows: in the no-choice set-up, twenty live or dead second instar (L2) larvae each ofHermetia illucens,Chilo partellus,Bactrocera invadens, andSchistocerca gregaria were administered separately to both male and female cages for six successive days. In the choice set-up, a mixture of twenty live or dead L2 larvae of the insects mentioned above was fed for twelve consecutive days. The control diets included an artificial diet only or artificial diet + corn leaves and were provided for six days consecutively to both males and females separately. In each case, the proportion of cannibalism and the possibility of hunting behaviour byR. differens was recorded. Cannibalism was significantly reduced in both male and femaleR. differens cages where prey was administered compared to the control diets. Besides, cannibalism was significantly reduced in both male and femaleR. differens cages when live insect prey was provided compared to dead insect prey. There were indications of a hunting behaviour exhibited byR. differens as they tended to feed more on living than on dead insect prey. Our findings show that the addition of live insect prey could reduce the prevalence of cannibalism duringR. differens, thus preventing colony collapse due to cannibalism and also providing a safe means to eliminate insect pests, which could serve as prey.