Inventory reveals wide biodiversity of edible insects in the Eastern Democratic Republic of Congo

In response to growing food demand, edible insects are perceived as an opportunity to alleviate food insecurity. With its wide edible insects’ biodiversity, the Democratic Republic of Congo is one of Africa’s most critical entomophagous. This study aimed at giving a first insight on inventory showing diversity, perception, consumption, availability, host plants, harvesting techniques and processing techniques of edible insects in South-Kivu, DRC. It recorded twenty-three edible insects belonging to nine families and five orders, some of which are consumed in the larval, adult, egg and pupa stages. Rhyncophorus phoenicis, Alphitobius diaperinus, Macrotermes subhyalinus and Acheta domesticus were the most preferred edible insects in Fizi Territory, Ruspolia differens and Apis mellifera larvae in Kabare Territory, Imbrasia oyemensis, Imbrasia epimethea, Rhynchophorus ferrugineus and Rhyncophorus phoenicis in Mwenga Territory, Ruspolia differens, Macrotermes subhyalinus, Gryllotalpa africana, Nsike, Nomadacris septemfasciata and A. mellifera larvae in Walungu Territory. Ruspolia differens, I. oyemensis, A. mellifera larvae, G. africana and Nsike, were preferred for their taste. Acheta domesticus, A. diaperinus and A. mellifera larvae were abundant throughout the year, while others were only available for 9 months or less per year. Numerous plants have been recorded as their hosts, including plants used for food and income. Harvesting strategies and period, processing methods and preservation techniques depend on insect species, local knowledge and practices. These findings suggest similar and thorough studies on entomophagy across the country while encouraging the rearing of edible insects to address their existing high demand and environmental concerns.

The Kabare Territory is located between 2° 30′ of South latitude and 28° 30′ of East longitude. Its altitude varies from ~ 1420 to 3200 m, and the Territory occupies an area of ~ 1690 km 2 with an estimated population of ~ 868,616, which makes it among the most populated in the South-Kivu province. The Territory is located in the medium to high altitude AEZ. Available meteorological data mentioned an annual rainfall average of ~ 1572 mm, and a temperature of ~ 22.6 °C. Most of Kabare is savanna with natural vegetation consisting of wild grasses.
The Mwenga Territory is located in the middle of the province and is the only Territory surrounded by the other without any country or province borders. It is located between 28° 25′ 29″ East longitude and 30° 02,16′ 05″ South latitude. Its altitude varies between 1500 and 1800 m in the northeast. In the centre and the South, it is more or less 670 m. In the East, it is more or less 200 m and in the West more or less 670 m. It has a humid tropical climate with two seasons: the dry season from June to September and the rainy season from September to May. The temperature varies between 21 and 37 °C in most of the Territory and is low in the Itombwe area because of the high altitude, which goes up to over 2000 m. Rainfall reaches 2000 mm to 3000 mm per year. The vegetation is mainly dense forest and savanna. The forest is home to the Itombwe Nature Reserve (RNI). Relief is dominated by the Itombwe mount uplands and the alluvial valley of the Elila watershed. Soils dominated with clayey (Humic Cambisols) and sandy soil (Acrisols) types.
The Walungu Territory is located between 2° 38′ of South latitude and 28° 40′ of East longitude. Its altitude varies between 1000 m and 2000 m with a cold tropical climate of low altitude. There are two seasons, the dry season (June to August) and the rainy season from September to March. Available station data presented an annual average of ~ 17-20 °C and 900 and 1500 mm for temperature and rainfall, respectively. The vegetation mainly consists of grassland, a few forest reserves of Mugaba and Mushwere and woodlands scattered throughout the Territory.
Sampling and selection of respondents. A total of 520 respondents, about 130 respondents in each Territory, were interviewed, with priority given to people familiar with entomophagy based on the main objectives set. Therefore, the respondents included adults, women and men over 18 years old and from all social classes. A structured oral interview was used individually to ensure better information and minimise external influences on the respondent's side.
Sources of data collected. Primary data were obtained from the field survey using three techniques: questionnaire administration, direct observations, and insect collection. www.nature.com/scientificreports/ Questionnaire administration. Structured questionnaires were used to obtain information on edible insects in all selected Territories of South-Kivu. The questionnaire was divided into seven sections. In the first section, information about the respondents was collected.
Section two contained open-ended questions related to commonly consumed edible insects, focusing on local names and stages of consumption. The third section contained questions about consumer preferences and preference factors. The fourth section included questions related to seasonal availability. In the fifth section, questions about host plants and signs of presence were asked, followed by personal observations. The sixth section dealt with harvesting techniques and timing. The last section dealt with processing methods and preservation techniques. The enumerators translated the questions into the local dialect to enhance the understanding of respondents. Pictures and real samples of various edible insects identified from the literature were also used to help respondents identify the insects being mentioned. Enumerators probed further to clarify some responses to enhance the depth of information solicited.
Direct observations. Direct observations of relevant information related to insects and their habitats in the different territories were recorded in the field. Pictures were taken to verify and support the responses obtained from the interviewees. In addition, the researcher had the opportunity to observe how some edible insects were prepared and consumed.
Collection and taxonomic identification of insect samples. Samples of edible insects were collected as part of the survey and were preserved in 70% alcohol before being taken to the laboratory at Lwiro Research Center for identification. A mixture of primary data and taxonomic characters was used to identify and classify the various species of edible insects in the different Territories. The taxonomic characters were derived mainly from archival sources and published literature.  The wide biodiversity of edible insect species revealed in South Kivu depicts the importance of entomophagy in the region. Our findings largely agree with that of Bomolo et al. 31 . They reported a list of eleven edible insect species belonging to four families in Haut-Katanga Province, confirming that the Democratic Republic of Congo has a high diversity of edible insects, making it one of the most important biological diversity in Africa. This biodiversity in terms of edible insects in DRC was also confirmed by Raheem et al. 24 , who reported on traditional consumption and rearing of edible insects in Africa, Asia and Europe. Similarly, Kelemu et al. 16 noted that most edible insects consumed in DRC belong to the orders reported in our findings.

Results and discussion
This diversity could be associated with the richness of the natural environment conditions 33 in each Territory as most edible insects are gathered from the wild 34 . In addition, the geographic distribution of host plants influences the availability of certain edible insects. A low number of caterpillar species has been attributed to marked deforestation, forest degradation and pollution 35,36 . This situation will likely worsen with the growing  37 . Previous studies reported that edible insect's consumption and preference are also influenced by their availability and cultures 38,39 . Findings from this study line with Raheem et al. 24 , who reported that more than a thousand insect species are worldwide consumed at some stage of their life cycle. In addition, Lepidoptera consumed as caterpillars and Hymenoptera are mostly eaten in their larval or pupal stages like the A. mellifera mentioned from the survey to be consumed as egg and pupa. Adults and larvae of Coleoptera are consumed, while the Orthoptera, Isoptera and Hemiptera orders are mostly consumed as mature adults 16 . Moreover, Kulma et al. 40 investigated the effect of developmental stage on the nutritional value of edible insects (Blaberus craniifer and Zophobas morio) reported no significant variations in basic nutrient content in protein quality expressed as the essential amino acid index. In contrast, they reported a significant difference in protein digestibility, fat content and lipid quality.
Familiarity appears to be the key driving force, allowing most respondents to react positively to all edible species in terms of their willingness to eat them and thus address food and nutrition insecurity and related issues. This preference has been reported to be linked to availability 13,41 , ethnicity/cultures 42 , palatability 14 and seasonality 43 , as some species are more prevalent and familiar in some Territories than others. In addition, indigenous knowledge and processing can also influence the preference of edible insect species 41 .
Bomolo et al. 31 revealed that caterpillar consumption is common among ethnic populations in D.R. Congo. This is not the case for Walungu, Kabare and Fizi, although it is the most appreciated edible insects in Mwenga. In Katanga, the Bemba and Lamba tribes have a long history of caterpillar consumption since the eighteenth and nineteenth centuries 44 , while the other tribes (Musanga, Tetela, Mongo, Baluba, Rund, Bacongo, Katshokwe, Emba, Songe, Ndembo, Kaminungu, Kalwena, Kete, Basankusu, Kanyoka, Sanga, Mbote, Yombe, etc.) appear to lack a strong history of caterpillar consumption. In addition, some of these tribes are reluctant to engage in Table 2. Commonly consumed edible insects in selected Territories of South-Kivu. + Insects present and consumed, − Insects not present, NI not identified. All of these edible insects are identified by local names, mainly in the dialects Kibembe (Fizi), Kirega (Mwenga) and Mashi (Kabare and Walungu) that are attached to specific physical characteristics or uses.  Preference for edible insects. The plotted data (Fig. 4) shows the appreciation factors for the most preferred inventoried edible insects (G. africana, R. differens, A. mellifera larvae, Nsike, N. septemfasciata and I. oyemensis) represented in two Territories (n = 260). Respondents rated them according to taste, size, shape, nutritional value and colour. Most of these insects were valued for their taste, especially R. differens (33%), I. oyemensis (32%), A. mellifera larvae (17%), G. africana (3%), and Nsike (2%), except for N. septemfasciata, which was valued for its size (3%) and shape (0.4%). As for size, R. differens (5%), G. africana (4%) and N. septemfasciata (3%) were the most valued. Most of these edible insects were not valued for their nutritional value or colour except for A. mellifera larvae (0.4%) and I. oyemensis (1%) for nutritional value and R. differens (3%) and Nsike (1%) for colour. Considering M. subhyalinus and A. domesticus represented in all Territories (n = 520). Irrespective of Territories, their appreciation depended only on their taste, size and shape (Fig. 5). More appreciation was based on the taste with 8% and 3% against 2% and 1% for the size for M. subhyalinus and A. domesticus, respectively; only M. subhyalinus was appreciated for its shape (1%).
Entomophagy habits differ from country to country and culture to culture, as do preference factors. Insect consumption depends not only on sensory characteristics 13 and nutritional value 10,41 but also on customs, ethnic preferences, prohibitions 7 , and medicinal properties 47 . Insects were once associated with filth, fear of contamination and disease, as well as psychological and biased thinking about taste, smell, and colour 48 , with a sense of disgust that entomophagy was motivated by starvation and is merely a survival mechanism 13 . This is far from the truth, as insects are not inferior to other protein sources, such as fish, chicken, and beef. However, it will take a bit more motivation to reverse this mentality 49 . It is possible to explore edible insects for consumption and increase the possibility of replacing animal products with insects, given that there is evidence that they are clean, tasty, and nutritious 50 .
In addition, insects have too many ecological advantages over other animal protein sources 6 . Some studies in European countries such as the Netherlands 51 on the acceptance of entomophagy have shown that people who have eaten insects in the past show significantly more positive attitudes towards entomophagy than people who have not and are more likely to eat them again. Therefore, it seems important to encourage people to take the "first step" and familiarize them with insect consumption. Therefore, consumer "education" about entomophagy should be practiced in its broadest sense 51 .      20 , who pointed out that most of the harvesting is done during the rainy season in Nigeria, especially for winged termites, cricket, caterpillars, A. domesticus, G. africana, and greenish beetle. Smith and Paucar 52 suggested that vibrations caused by rain and the sound of thunder would trigger their emergence. Chakravorty et al. 14 also confirmed that the availability of edible insects is seasonal, stating that peak numbers of edible beetles occur from June to September before decreasing in winter and early spring. They also reported that Odonata and Orthoptera were most abundant in September and October (late summer).
Insects of the order Hemiptera and Hymenoptera are less abundant from November to February (winter), while others such as bugs and ants are available throughout the year. This would be attributed to seasonal   www.nature.com/scientificreports/ changes in various regions of the world. In the Central African Republic, the average consumption of caterpillars increases due to their greater abundance during the rainy season 13 , as seasonal availability and edible insect consumption are correlated 15 . In contrast to our findings, all developmental stages of R. differens can be found throughout the year in non-swarming populations but at low densities during dry seasons and high densities during rainy seasons 53 . Ebenebe and collaborator 20 highlighted that certain edible insects are associated with the following host plants: cricket-yam; yam beetle-yam; African palm weevil-raffia palm; Rhinoceros beetle-raffia palm, oil palm, coconut tree; butterfly-iroko (Chlorophora excelsa), locust bean seed (Parkia biglobosa), flamboyant tree (Delonix regia), croton (Croton tiglium) and ngwu tree; grasshopper and honey bee-Jatropha gossyplifolia, Citrus sinensis, Morinda lucida, Psidium guajava and Sarcocepha laifolius. According to Ngute et al. 54 , five of the eleven caterpillar species studied in central Cameroon were reported to have only one host plant, while others had more than one. They identified eighteen plants, of which eleven are restricted to natural forest habitats, including Entandrophragma cylindricum and Baillonella toxisperma. Although many of the identified caterpillar host plants are generally  54 . Also, it should be noted that most of the hosts are plants used as a source of food and revenue; for example, B. toxisperma is a class A timber species, which produces fruits with a highly valued and edible oil is extracted 55 . It has been reported that out of 21,252 observations, R. differens were observed 20,915 (98%) times on grasses and sedges, with a total of 19 grass species (Poaceae) and two sedge species (Cyperaceae). Among the grasses the dominant species were P. maximum, B. ruziziensis, C. gayana, H. rufa, Cynodon dactylon, Sporobolus pyramidalis and P. purpureum 53 . When reared in the laboratory, R. differens accept artificial food, leaves, flowers, and grains of many types of grass, including cultivated cereals 56,57 . At this point, our findings line with those of Meutchieye et al. 19 , who observed that the cracking noises in the palm trunks three to four weeks after the final collection of palm wine, the yellow of the internal raffia bamboo, caterpillar odours and typical bird songs and whistling are the signs indicating the presence of R. phoenicis, caterpillars, R. differens and field crickets.

Host plants for various inventoried edible insects.
Harvesting and processing techniques of edible insects. Thistudyfound that harvesting time and techniques vary according to local knowledge, practices, and insect species (Table 5). Three harvesting techniques were identified, including trapping, collection. M. subhyalinus (during and after the first rains) and R. Processing methods and preservation techniques vary according to the type of edible insect and the purpose, whether for direct consumption or preservation. Generally, they are all dried or dry-fried for preservation except for the honeybee ( These results are consistent with those of Meutchieye et al. 19 , as well as those of Ebenebe et al. 20 , who also pointed out that hand picking is one of the major techniques used to harvest crickets, Rhinoceros beetle, stinking grasshopper (in the early hours of the morning), African palm weevil (from rotting palm tree) and caterpillars. In contrast, light trapping is used to harvest termites, green grasshoppers, house cricket and mole cricket. In addition, Ebenebe et al. 20 added that crickets were also harvested by digging out from the tunnels during the dry season and that house cricket was also harvested by digging out from small sound mounds with depression that indicates their entrance. In contrast to the results of this study, Ebenebe et al. 20 stated that mole crickets were harvested by light trapping. Singing a "Wee wee" song at the base of the host tree is another notable technique used to harvest the caterpillar of a particular moth species. The more you sing, the more they fall from the top of the tree and are harvested.
To harvest enough R. differens by light trapping during the swarming season, locals lit the lamps/bulbs outside the houses and secure the areas where these lamps/bulbs are located with corrugated iron sheets bent into a cone shape leading to baskets, small drums where the falling R. differens are harvested 58 . For non-swarming R. Differens, harvesting is done early in the morning between 6 and 7 AM, when they are inactive and unable to fly 17 . Dao et al. 59 also reported two harvesting techniques: direct termite collections from their mounds and termite trapping in containers. The direct collection involves partially destroying termite mounds, while trapping implies looking for signs of termite presence such as mud sheets and tracks on the ground. Techniques depend on the termite genus. Small termite mounds of Trinervitermes and Cubitermes can be dug with a hoe or pickaxe, and the mounds are collected in the morning between 6 and 9 AM. The traps are placed between 6 and 8 AM or in the evening around 6 PM. They are covered with foliage or pieces of cloth to protect them from the sun. The same harvesting techniques were recently described in Ghana 60 .
It was reported that edible insects were sun-dried, baked, steamed and processed into crackers, muffins and sausage meat 61,62 . Our findings confirm those of Ebenebe et al. 20 , who also found that salted roasting is one of the techniques used to process termites, crickets, Rhinoceros beetle, grasshopper and locust. They added that grasshopper and locust are consumed dried as well. On the other hand, African palm weevils are consumed raw or fried with pepper sauce. This study found that drying was the most used preservation technique as it is the most widely used technology for increasing the shelf-life of foods. The drying ranges from traditional, including roasting, frying and solar drying, to modern freeze-drying and microwave-assisted drying 63 .

Conclusion and recommendations
The wide biodiversity of edible insects observed depicts the importance of entomophagy in the region. Twentythree edible insects were recorded belonging to nine families and five orders. These insects are consumed as larvae, adults or as eggs and pupa. About four of them were the most popular edible insects in Fizi and Mwenga, two in Kabare, and six in Walungu Territory. Additionally, R. differens, I. oyemensis, A. mellifera larvae, G. africana and Nsike were the most preferred for their taste. Besides, some are available throughout the year, while the others are less available. Many plants have been recorded as host plants, including plants used as food sources, feed and income for humans. Harvesting strategies and time, processing methods, and preservation techniques vary according to local knowledge and practices and insect species. These findings suggest similar studies in other provinces and further research on the nutritional and safety profiling of processed and non-processed edible insects while encouraging the rearing of certain edible insects for mass production as the demand is too high.