Edible insect biodiversity and anthropo-entomophagy practices in Kalehe and Idjwi territories, D.R. Congo

Commonly consumed edible insects in selected territories of South-Kivu

Nine edible insects were identified in Kalehe and Idjwi, namely Ruspolia differens, Gryllotalpa Africana, Locusta migratoria, Macrotermes subhyalinus, Gnathocera trivittata, Rhynchophorus phoenicis, Vespula spp., Apis mellifera, and Imbrasia oyemensis (Table 3). Most of the recorded edible insects are used as food sources in both Kalehe and Idjwi territories (I. oyemensis, L. migratoria, A. mellifera, M. subhyalinus, and R. differens), while G. trivittata, R. phoenicis, and Vespula spp. are only used in Idjwi, and G. africana is only used in Kalehe (Fig. 3). Some of the insects are consumed as larvae including I. oyemensis, A. mellifera, R. phoenicis, and Vespula spp., while others are consumed as adults such as L. migratoria, M. subhyalinus, R. differens, G. trivittata, and G. africana. Unlike others, I. oyemensis is consumed as both larvae and pupae, while A. millifera is consumed as egg, larvae, and pupae. Honey is also prized much for consumption and commerce.

Table 3 Inventoried edible insects in Kalehe and Idjwi territories, Republic Democratic of CongoFig. 3figure 3

a I. oyemensis (Caterpillar); b L. migratoria (Migratory locust); c A. mellifera larvae (Honey bee); d M. subhyalinus (Termite); e R. differens (Grasshopper); f G. trivittata (Nsike); g R. phoenicis larvae; h G. africana (Mole cricket); i Vespula spp. larvae (Wasp)

All the insects have local names derived from the Kihavu and Kitemba dialects referring to physical characteristics or uses. Among them, we found Madaku for I. oyemensis, L. migratoria (Mikelele, Ihanzi, and Panzi), A. mellifera (Binyangu and Lwasso), M. subhyalinus (Iswa and Muchocholi), R. differens (Misanani and Miguku), G. trivittata (Nsike), R. phoenicis (Bihombogolo), and G. africana (Nkwananzi) and Nsimbwe for Vespula spp.

Preference for inventoried edible insects

Ruspolia differens and M. subhyalinus were the most preferred edible insects in both territories (Fig. 4). In Kalehe, R. differens was the most preferred by respondents (32%) followed by M. subhyalinus (26%), G. africana (16%), L. migratoria (15%), A. mellifera (6%), and I. oyemensis which were the least preferred (5%). In Idjwi, R. differens was the most preferred by respondents (35%) followed by M. subhyalinus (20%), L. migratoria (14%), and I. oyemensis (7%), with R. phoenicis (5%) and Vespula spp. (3%) being the least preferred after A. mellifera and G. trivittata (8%).

Fig. 4figure 4

Edible insects’ preference (n = 260, about 130 respondents in each territory)

Factors influencing preference

The preference for various edible insects inventoried in the Kalehe and Idjwi territories was found to be influenced by several of factors including taste, shape, size, perceived nutritional value and their colors as plotted in Figs. 5 and 6. Most of them were appreciated for their taste (R. differens, M. subhyalinus, L. migratoria, and G. trivittata) and nutritional value (A. mellifera, I. oyemensis, and R. phoenicis).

Fig. 5figure 5

Factors of preference of edible insects in Kalehe Territory (n = 130). Respondents gave reasons for preferring one edible insect over another. The preference was based on taste, size, shape, perceived nutritional value and color

Fig. 6figure 6

Factors of preference of edible insects in Idjwi Territory (n = 130)

In Kalehe Territory, G. africana was appreciated (18%) for its taste, for its size (44%), for its shape (34%), and for its perceived nutritional value (4%). I. oyemensis was appreciated for its taste (32%) and perceived nutritional value (68%). L. migratoria was appreciated by 60%, 3%, 28%, and 9% for its taste, size, shape, and nutritional value, respectively; A. mellifera larvae were only appreciated for their perceived nutritional value. Macrotermes subhyalinus was, respectively, appreciated by 41%, 38%, 20%, and 1% for taste, size, shape, and nutritional value, while R. differens was more appreciated for its taste (56%) and moderately appreciated for its shape (42%). G. africana was appreciated by 18%, 44%, 34%, and 4% for taste, size, shape, and nutritional value, respectively. No edible insects inventoried were appreciated for their color in Kalehe.

In Idjwi Territory, it was revealed that taste and nutritional value were the main factors of preference (n=130) for edible insects (Fig. 4). M. subhyalinus (60%), L. migratoria (55%), R. differens (50%), G. trivittata (43%), I. oyemensis (40%), and Vespula spp. (40%) were the most appreciated for their taste, while R. phoenicis (70%) and A. mellifera larvae (60%) were the most appreciated for their nutritional values. In contrast to Kalehe Territory where no edible insects were appreciated for their color, some edible insects were slightly appreciated in Idjwi Territory including G. trivittata (5%), A. mellifera larvae (3%), and L. migratoria (2%).

Principal component analysis (PCA biplot) results indicated that the two axes accounted for up to 71.64% of the observed variability in the preference of edible insects in Kalehe and Idjwi based on the preference factors (Fig. 7). The first and second axes accounted for 47.95% and 23.69% of variability, respectively.

Fig. 7figure 7

PCA biplot of preference factors

A scatter plot of matrices (SPLOM), histograms, and Pearson correlations between preference factors show a negative correlation between preference based on taste (r=-0.69), size (r = −0.53), and shape (r = −0.76), and preference based on nutritional value as depicted in Fig. 8.

Fig. 8figure 8

Scatter plot of matrices (SPLOM), histograms, and Pearson correlations between consumer preference factors

Seasonal availability of inventoried edible insects

Recorded information on the seasonal availability of inventoried edible insects in Kalehe and Idjwi territories showed that some are available throughout the year, while others are only available for 9 or even 4 months (Table 4). Like A. mellifera, L. migratoria is available throughout the year in both territories except that the latter is less available for 7 months in Kahele and 6 months in Idjwi. Some species are available for 9 months (R. differens in Kalehe, G. africana and I. oyemensis in Idjwi), others for 8 months (I. oyemensis in Kalehe, M. subhyalinus and R. differens in Idjwi), 7 months (G. trivittata and R. phoenicis), while Vespula spp. is only available during 4 months, of which 2 months of more availability and 2 months of less availability. Most of them are available in the rainy season, which runs from September to May in Kalehe and from September to April in Idjwi. Only species such as A. mellifera and L. migratoria are available in the dry season (June to August) in Kalehe, but the latter is not more available in this season. In contrast to Kalehe, four species of edible insects (L. migratoria, A. mellifera, G. trivittata, and Vespula spp) are available in Idjwi during the dry season.

Table 4 Seasonal availability for various consumed edible insectsHost plants for various inventoried edible insects

While some edible insects require plants to serve as food sources or habitats, others do not necessarily need a host plant to survive. Table 5 shows that L. migratoria and R. differens are associated with crops such as Zea mays, Sorghum bicolor, Phaseolus vulgaris, Ipomoea batatas, Oryza sativa, Saccharum officinarum, and Arachis hypogaea as a food source or habitat, which are also used as staple food for humans in Kalehe and Idjwi territories. On the other hand, R. phoenicis feed on Elaeis guineensis and Raffia palm which are used for food and economic purposes. Apis mellifera is a pollinator and plays a critical role. Macrotermes subhyalinus and G. africana do not necessarily require a host plant. Indicators of their presence vary from species to species. The I. oyemensis is noticed by caterpillar smell and consumption of leaves, while L. migratoria is noticed by whistling, G. africana by whistling and canals in the wet ground, and R. phoenicis is noticed by cracking noises in palm trunks and odor.

Table 5 Host plants for various consumed edible insects in Kalehe and Idjwi territoriesHarvesting techniques and processing methods of edible insects

Harvesting techniques and period as well as processing methods and preservation techniques depend on the edible insect species, local knowledge, and practices (Table 6). Generally, two main techniques are used for harvest, namely handpicking and light trapping. The handpicking technique is used for I. oyemensis, L. migratoria, G. africana, and R. phoenicis, while A. mellifera and Vespula spp. are harvested. Unlike those species which are either only handpicked or harvested, R. differens and M. subhyalinus (during and after the first rains) are both light-trapped and handpicked. The harvesting period can be anytime during the day for some species such as I. oyemensis, R. phoenicis, and Vespula spp. Others including L. migratoria and R. differens are handpicked in the morning hours before sunrise when they are still weak and cannot fly. The eggs, larvae, and pupae of A. mellifera are preferably harvested at night.

Table 6 Harvesting techniques and processing methods for various consumed edible insects in selected territories

Processing methods and preservation techniques vary from species to species and purposes whether it is for direct consumption or preservation for further uses or market. Some species are boiled (I. oyemensis, and the larvae of A. mellifera and Vespula spp), fried (I. oyemensis and G. africana), or dry-fried (L. migratoria, M. subhyalinus, R. differens, and R. phoenicis), stewed (I. oyemensis and R. phoenicis), roasted (L. migratoria, R. differens, G. africana, I. oyemensis, and M. subhylanus), and sometimes eaten raw (M. subhyalinus). All edible insects with wing (L. migratoria, M. subhylanus, R. differens, and G. africana) are first de-winged before being processed. If there is enough to preserve, most of the edible insects are usually dried (I. oyemensis, L. migratoria, M. subhyalinus, G. africana, and R. phoenicis) or dry-fried (R. differens) except for the immature stages of A. mellifera and Vespula spp. All edible insects with wings (L. migratoria, M. subhylanus, R. differens, and G. africana) are first de-winged before being processed.

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