Species diversity

We recorded 16 consumed insects belonging to 5 orders and 10 families (Table 3 and Fig. 2). Nine medicinal insect species were also documented, belonging to three orders and five families (Table 4 and Fig. 3). Four wasp species were used both in entomophagy and medicinal practices, where the adult was used for medicine, and the larvae and pupae used for food. However, of the 21 species documented, only 16 species have specimens and 15 species were successfully identified (except an antlion, a larva of Myrmeleontidae). These specimens were deposited in Guangxi Normal University. Samia ricini and Bombyx mori were identified without voucher specimen as they were important and widely raised cash insects in China in the past. Euconocephalus sp. was confirmed through photographs. Two unknown species were locally called Niujiaolang (a wasp) and Mujichong (a scarab larva), both of which were not found in the field and confirmed via photographs.

Table 3 Edible insects consumed in the study areaFig. 2

Edible insects collected in the study area (Photos are not scaled). A. The nest, larvae, pupae, and adult of Vespa affinis. B. Vespa basalis. C. Parapolybia varia in house. D. Vespa bicolor. The wasp invaded and built a nest in an artificially cylindrical beehive. E. Vespa velutina and its nest hanging on the ceiling. F. Vespa ducalis. G. Polistes olivaceus. H. Tessaratoma papillosa. I. Cyrtotrachelus longimanus. J. Gryllotalpa orientalis. K. Anomala chamaeleon

Table 4 Medicinal insects used in the study areaFig. 3

Medicinal insects and medicinal liquor collected in the study area (Photos are not scaled). A. Antlion. B. Pycnoscelus surinamensis. C. The larva of Periplaneta australasiae. D. The larva of Periplaneta americana. E. The medicinal liquor of Vespa bicolor. F. The medicinal liquor of Vespa ducalis. G. The medicinal liquor of Vespa affinis. H. The medicinal liquor of Xylocopa dissimilis

Almost each of the species has a local name (Table 3 and Table 4). However, the criterion adopted by the local villagers was unclear for distinguishing the wasps, as the name ‘Guanfeng’ or ‘Tanfeng’ was assigned to Vespa affinis, Vespa basalis, and Vespa velutina, possibly due to locals perceiving similar morphological and behavioral characteristics, such as crock-shaped nests and black bodies. Only a few respondents (n = 3) could distinguish V. velutina from Guanfeng and called it ‘Huangjiao’ as the species has yellow feet.

Respondents’ characteristics and insect use

In total, 207 interviewees (95.8%) had mentioned edible or medicinal insects, of which 205 had consumed insects and 137 mentioned the medicinal species (Table 2). A positive relationship was observed between the number of listed insects and the respondent’s age (r = 0.606, n = 207, p < 0.001), while a negative correlation was found between the number of listed insects and educational achievement (r = -0.476, n = 207, p < 0.001). There was also a significant association between the number of listed insects and livelihood (x2 = 38.776, df = 3, p < 0.001). Individuals with a stable income (formal employment) mentioned fewer insects. However, no significant association was found between gender and the number of listed insects (p = 0.11).

A few respondents (n = 11) had never consumed insects and had negative attitudes toward entomophagy, except a teenager who was willing to try them. Some of these respondents (n = 4) stated that “Insects have no value, but during times of hardship, people would be too hungry and would eat them.” Others (n = 6) said that the negative psychological effects caused by the appearance or behavior of insects, such as fear and nausea, made them unacceptable as food. However, among these respondents, one man (48 years old) was able to list Guanfeng, and a woman (34 years old) was able to list Euconocephalus sp., Gryllotalpa orientalis, Parapolybia varia, Guanfeng, Vespa bicolor, Polistes olivaceus, and Niujiaolang, because they had collected these insects for family consumption.

Cultural importance of edible insects

The palatability of insects was the main reason mentioned for their consumption. Consumers did not perceive entomophagy as a means of dealing with starvation or for nutritional supplementation. They regarded edible insects as delicacies, consuming whole insects as snacks and dishes. Among the documented species (Table 3), Euconocephalus sp. was consumed most frequently, followed by P. olivaceus, G. orientalis, P. varia, Guanfeng (V. affinis, V. velutina, V. basalis), and V. bicolor.

The most culturally salient insect was Euconocephalus sp. (S = 0.96), followed by G. orientalis (S = 0.85), Anomala chamaeleon (S = 0.76), Cyrtotrachelus longimanus (S = 0.75), silkworms (Samia ricini and Bombyx mori) (S = 0.63), Tessaratoma papillosa (S = 0.6), and Mujichong (S = 0.58). The values were lower than 0.5 for the other species (Table 3). The order Coleoptera was the most culturally important, reaching the highest total salience index (S = 2.09), followed by Hymenoptera (S = 1.91), Orthoptera (S = 1.81), Lepidoptera (S = 0.63), and Hemiptera (S = 0.6).

Edible insect collection and preparation

All of the edible insects recorded in this survey were harvested in the wild except S. ricini and B. mori, which locals reared. We recorded the collection and preparation practices according to taxonomic groups.

Wasps

Local inhabitants were familiar with suitable habitats for wasps’ nests due to long-term collecting practices and life experiences (e.g., wasp stings have led locals to consciously pay attention to the locations of nests). In most cases, locals collected wasps when they hunted, grazed cattle, gathered firewood, picked wild fruits, or searched for plant medicines in the mountains. They searched for wasp nests by observing wasps’ flight direction and hearing their sounds. At other times, they would accidentally get stung first and then notice the nest nearby. However, they believed that wasps would not attack humans unless the wasps were disturbed. During summer vacations, children became important discoverers of wasps’ nests.

The locals use fire to produce smoke and high temperatures to drive out or destroy swarms. They never consumed adult wasps and regarded them as dangerous and poisonous; therefore, they only collected larvae and pupae. P. olivaceus (Fig. 2G) and P. varia (Fig. 2C) were collected from thickets, thorny bushes, and even houses, as they may build nests on ceilings, crossbeams, widows, cupboards, and other hidden areas. P. varia has a thin waist, and its nest resembles the ear of cattle. Their vernacular names (Huayaofeng and Niuerfeng) were used based on these noticeable characteristics. They are not an aggressive species, and minimal smoke is needed to expel the swarms from their nests. However, when stung, acute pain, partial redness, and swelling would appear and take approximately 30 min to resolve (30 mentions).

V. affinis (Fig. 2A), V. velutina (Fig. 2E), and V. basalis (Fig. 2B) typically build nests in thorny bushes and tall trees around houses or in the forests. They also build nests on the ceilings and crossbeams of houses. The nests of V. bicolor (Fig. 2D) are generally found in the hollows of trees and burrows and, occasionally, in houses. Moreover, V. affinis and V. bicolor may occupy the same location year after year. Two men stated that they harvested the nests of V. affinis at the same location for two consecutive years, while one woman stated that she found V. bicolor nests on the same branch for two consecutive years. In contrast, V. ducalis (Fig. 2F) only builds nests underground. These five species are extremely aggressive, with venom containing toxic and allergic components [42, 43]. According to respondents (n = 62, 28.97%), after being stung, symptoms including sharp pain, numbness, skin redness, and swelling (as well as chills and dizziness if the victim was stung in the head) would appear quickly, and the symptom duration was long (at least several hours). Essential balm (a Chinese herbal oil for pain relief) is used to alleviate pain but has little effect. There are no efficient traditional therapies for stings, and sufferers rely primarily on immune ability. If a sting causes a severe allergic reaction, locals go to the hospital for treatment immediately. Although these wasps can be dangerous, the locals would not give up these delicacies. The harvesting season was from summer to autumn. The local saying “Guan (V. velutina, V. basalis and V. affinis) in July, Diwa (unknown) in August, Huangjiang (V. bicolor) in September, Baiyizhuo (V. ducalis) in October” lists the optimal harvesting stages for each species according to the lunar calendar. The unidentified ‘Diwa’ is a species that builds nests underground (whose name means ‘dig the ground for nests’). However, the Diwa consumers (n = 8, all over 60 years old) indicated that the species had not been observed for many years and may have disappeared from the region.

Males were the predominant wasp collectors. Some respondents (n = 6, 2.8%) stated: “It is easy to explain but hard to perform, and the biggest obstacle is fear.” The wasps were generally collected during the daytime. Collectors wore thick raincoats and rain boots or other clothes covering the entire body. Long bamboo poles, hemp rope, iron hooks, firewood, and cloth or mesh bags were used for collection. Sometimes, thick gloves, shovels, a firewood chopper, and a ladder were also needed. When a nest was built on a high branch, firewood was tied to the end of a bamboo pole and then ignited to expel the swarms. A hook connected with hemp rope was used to pull off the nest. Some respondents (n = 4, 1.86%) conducted collections at night, especially for large nests and underground nests with massive swarms. Before collection, they located the entrances of the nests and observed swarm activities in the daytime to determine the best burning position. When swarms congregated in and around the nest at night, collectors would light a fire, and the swarms would fly into it due to phototaxis. Another method mentioned by the respondents (n = 2, 0.93%) was using spider threads to block the exits of a nest at night. Then, while wearing thick gloves, collectors would take the nest using a flour bag. This method was only applied to the nests of V. affinis, as the entire swarm returned to the nest at night.

The larvae and pupae of these species were fried with salt, which gave them a crispy and salty taste. The species size varied, with the largest being V. ducalis, followed by V. affinis, V. velutina, V. basalis, P. olivaceus, and P. varia. Some consumers preferred larger sizes, but most consumers exhibited no size preference.

Hemiptera

T. papillosa (Fig. 2H) is a stinkbug that can eject a yellow, pungent liquid. This species is mainly collected in the summer from fruit trees, such as Dimocarpus longan, Litchi chinensis, and Phellodendron chinense. Harvesters collect them by hand without any protective measures. Hence, their fingers can stain yellow and need some time to recover. Some respondents (n = 6, 2.8%) believed the pungent liquid could burn their skin. The stinkbugs are placed in water to eliminate the odorous chemicals, then boiled, and fried. Alternatively, they are baked after stuffing the leaves of Mentha cannadensis, Perilla frutescens, Ocimum basilicum, or Piper sarmentosum into their abdomens. However, most interviewees disliked T. papillosa due to the scent chemicals and found them unacceptable as food. In addition, the stinkbugs were the main pest of fruit trees. Therefore, locals usually use pesticides to kill them rather than eat them. Many consumers of stinkbugs responded that they had stopped eating them for many years. As such, the consumption of T. papillosa has substantially declined.

Lepidoptera

The locals used to rear S. ricini and B. mori in spring and summer using the leaves of planted mulberry (Morus alba) and cassava (Manihot esculenta). They would extract the pupae and sell the cocoons. Eating fried pupae was customary until buyers indicated they wanted intact cocoons. Hence, locals gradually gave up eating the pupae as the main purpose of rearing the insects was to earn income. Currently, only a few locals have engaged in silkworm breeding, as they consider the work difficult with a low economic return. The last silkworm breeding was said to have occurred five years previously. As a result, while some consumers said they would buy the pupae to eat, none were available in local markets.

Orthoptera

G. orientalis (Fig. 2J) and Euconocephalus sp. were collected from paddy fields. Local inhabitants collected G. orientalis when they plowed and raked fields, as it lives underground, especially in fertile farmlands. They were caught by hand, with bottles or buckets used as containers. The collected insects were then rinsed with clean water, salted, and fried. Euconocephalus sp. was collected during summer rice harvesting. Locals also caught them by hand, pulling their wings and mandibles out to prevent them from escaping and biting. They would then be placed in a cloth bag. These insects were fried after cleaning.

Coleoptera

C. longimanus (Fig. 2I) is a primary pest of bamboo. They nibble on and tunnel into bamboo shoots, making them yellow, shriveled, and full of small holes. These characteristics were used as clues by locals to find juvenile insects. For adult C. longimanus, local people took advantage of their characteristic death mimicry behavior by shaking bamboo so they would fall to the ground. Another method was using sticks to knock adults out of the bamboo. Both larvae and adults of C. longimanus were consumed after frying or baking.

The consumption of A. chamaeleon (Fig. 2K) occurred in the past. Consumers of this species were all 44 years or older and explained that the species’ suitable habitat had disappeared as the local vegetation was transformed into bamboo forest approximately 35 years ago. They reported that these insects would hide in the sand in the daytime and gather in groups on the sand’s surface at night. Thus, they collected A. chamaeleon on the sand of the river bank at night. The insects were found using moonlight or flashlight, and bottles were used as containers. The wings of the collected insects were removed, and the bodies were then cleaned, salted, and fried. In the study area, A. chamaeleon was called “yellow insect,” and Anomala cupripes (Hope, 1839) was called “green insect.” These two species are similar in morphology except for their coloration. Local belief states that the yellow insects became green after the Qingming (sweeping tomb) Day, as A. chamaeleon was rare or disappeared, but A. cupripes emerged after this day. Locals never consumed A. cupripes as they claimed, “No one would eat the green insect (A. cupripes).”

Edible insect population trends

According to the respondents, Euconocephalus sp., G. orientalis, and A. chamaeleon populations have declined in the study area. Most interviewees (n = 73) believed that the extensive use of pesticides has led to declines in Euconocephalus sp. and G. orientalis populations. Some (n = 3) indicated that the use of chemical fertilizer may have had a negative effect on G. orientalis. One farmer believed that replacing cattle with machinery for plowing farmland in winter may have adversely affected G. orientalis populations. As for A. chamaeleon, it is quite rare due to the loss of suitable habitat (129 mentions).

In contrast, wasp populations were reported to be increasing. The reasons given for this were varied. First, wasp nests were frequently observed in or around houses, especially P. olivaceus (15 mentions), V. affinis and V. velutina (15 mentions), and V. bicolor (8 mentions). Second, in the past, many locals collected wasps’ nests during the harvest seasons because they grazed their cattle and gathered firewood in the mountains nearly every day. However, in recent years, the number of cattle herders has substantially decreased as machinery is used to plow the land, while most households now use electricity and gas for cooking. In addition, many locals do not need to work in the wild as frequently as in the past. Therefore, the declining frequency of harvesting may have promoted the expansion of wasp populations (7 mentions). Third, five beekeepers stated that the frequency of wasps preying on their breeding bees and encroaching into beehives has increased in recent years.

Entomo-therapeutic practicesCockroaches and antlions

Antlions and cockroaches (Pycnoscelus surinamensis, Periplaneta australasiae, and P. americana) were used alone or in combination to treat common cold symptoms in infants (e.g., by concocting an elixir using approximately 10 antlions, 1–2 cockroaches, or 5 antlions mixed with 1–2 cockroaches) (Fig. 3 and Table 4). These insects were readily available in rural areas. Locals generally captured them from woodsheds and in the corners of houses. The live insects were disinfected in boiling water, pounded, mixed with warm water, and drunk.

Medicinal liquor

V. bicolor, V. ducalis, V. affinis, V. basalis, and Xylocopa dissimilis were used to make medicinal liquors to treat rheumatism (Fig. 3 and Table 4). When collected for medicinal purposes, locals wore protective clothing to catch adult wasps instead of smoking them out of nests. Because V. bicolor, V. affinis, and V. ducalis prey on bees, collectors also waited at apiaries and used insect nets to catch them. X. dissimilis lives in dry bamboo, and even bamboo poles used to hang clothes were suitable habitats for X. dissimilis, which could be found by the holes they made. Collectors stated that the number of X. dissimilis typically found in one pole was approximately 10 individuals. To collect them, they blocked the holes with net bags and drove them into the bags by hitting the bamboo or using smoke. X. dissimilis is an aggressive species. One woman who was stung in the arm experienced partial edema and intense pain for two days. The collectors usually directly shook these insects from containers into alcohol, although other methods include freezing the insects in refrigerators or scalding them with boiling water to render them immobile and then immediately placing them into alcohol. After a month of soaking, the infused alcohol can be drunk. However, the frequency and amount of liquor consumed must be monitored due to its side effects. Excessive drinking can cause "shanghuo," which causes patients to experience toothaches and a sore throat. Locals suggested drinking a small cup of medicinal liquor (around 15 ml) a day to treat rheumatic pain.

Informant consensus agreement on entomo-therapeutic practices

There was a high consensus (ICF = 0.98) (Table 4) among informants concerning the use of antlions and cockroaches to treat the common cold in infants. However, a relatively lower consensus (ICF = 0.43) was observed for treating rheumatism with medicinal liquor.