The increased attention given to health, food security, and biodiversity conservation in recent years should bring together conventional scientists and indigenous people to share their knowledge systems for better results. This work aims to assess how grasshoppers are perceived by the local people in southern Cameroon, particularly in terms of food, health, and landscape conservation. Villagers were interviewed individually using a rapid rural assessment method in the form of a semi-structured survey. Nearly all people (99%) declared that they are able to identify local grasshoppers, generally through the color of the insect (80%). Crop fields were the most often cited landscape (16%) in terms of abundance of grasshoppers, with forest being less mentioned (8%). In general, villagers claimed that grasshopper abundance increased with forest degradation. Grasshoppers were found during all seasons of the year but noted to be more abundant during the long dry seasons. People found grasshoppers both useful and harmful, the most harmful reported being Zonocerus variegatus, an important crop pest. Cassava is the most attacked crop with 75–100% losses. Industrial crops, such as cocoa, coffee, and bananas, were not cited as being damaged by grasshoppers. The most effective conventional method cited for the control of pest grasshoppers is the use of pesticides (53%) with, in most cases (27%), a 75–100% efficiency. The traditional method of spreading ash was also often cited (19%), with an estimated efficiency of 25–75%. Biological methods were neither cited nor used by the villagers. Most of them (87%) declared that they eat grasshoppers; some sold these insects in the market (58%) and some used them to treat diseases (11%).

biodiversity conservation, Caelifera, crop pest, disease, indigenous people, Orthoptera

Sustainable development is now emerging as an alternative to conventional development as a way to reduce poverty in the Third World (UN 2019). A sustainable development perspective is consistent with the need to conserve ecosystems and agro-systems for better development (Ulluwishewa 1993, Andres and Bhullar 2016). In the last century, ecosystem transformations due to agricultural intensification and rapid industrial and urban development have imposed pressures on biological diversity, such that there is an urgent need to create interest and awareness regarding functional biodiversity (Rastogi and Kumar 2009, Rastogi 2011), biodiversity conservation (Kearns 2010), and the economic resources provided by biodiversity (Nijkamp et al. 2008). Accelerated exploitation of natural resources in the Third World leads to environmental degradation and loss of biodiversity, which, combined with the harmful effects of climate change, threatens to reverse decades of development efforts and have a negative impact on agriculture, health, settlement, and infrastructure in developing countries (Thornton et al. 2011). As a Sub-Saharan African country, Cameroon is seriously affected because it depends mainly on rain-fed agriculture. Due to the current effects of climate change, the livelihoods of local farmers are vulnerable to unpredictable floods, prolonged droughts, and related famine, pests, and diseases, thus calling for adaptive strategies to be undertaken (Akinnagbe and Irohibe 2014, Torquebiau et al. 2016). Early warning systems have proven to be indispensable in preparedness for such climatic consequences (Tadesse et al. 2008, Singh and Zommers 2014). This increased attention to climate change and landscape degradation is bringing together both conventional scientific and indigenous communities to share their knowledge systems (Nakashima et al. 2012). Historically and to date, local communities in different parts of the world have continued to rely on indigenous knowledge to conserve the environment and deal with natural disasters (Iloka 2016). However, various people now consider that, especially in Africa, the knowledge of indigenous people should be included when designing adaptations to natural disasters and particularly to climate change (Robinson and Herbert 2001, Joshua and Jürgen 2013).

Indigenous knowledge can be defined as a set of strategies, practices, tools, explanations, beliefs, intellectual sources, and other values accumulated through time by indigenous communities without interference or involvement of hegemonies or external forces (Emeagwali and Sefa-Dei 2014). The knowledge of indigenous communities has been accumulated through generations of living in a given environment and allows the members of these communities to live in harmony with nature; this knowledge provides valuable tools for food security, health, education, environmental conservation, and the reduction of the degradation of natural resources. To a certain extent, indigenous knowledge allows for the foreseeing of hot weather, periods of seeding, and anticipation of the rainy season (Mwaura 2008). The use and application of appropriate indigenous knowledge systems can promote environmental conservation and aid in the management of disasters in terms of disaster prevention, mitigation, recovery, prediction, early warning, preparedness, response, and rehabilitation (Mwaura 2008). In Africa, the indicators used by indigenous knowledge systems include temperature variation, astronomical observations, plant phenology, and the behavior of birds, amphibians, reptiles, and insects (Mwaura 2008). In Tanzania, various environmental and astronomical means have been used to predict rainfall, including plant phenology and the behavior and movement of animals such as birds and insects (Chang’a et al. 2010). In Uganda, indicators for the onset of the dry season include the appearance and movement of insects, specifically butterflies, red caterpillars, western honeybees (Apis mellifera Linnaeus, 1758), and bush-crickets (Ruspolia baileyi Otte, 1997; Joshua and Jürgen 2013). In Ghana, the presence of the bird Butastur rufipennis Sundevall, 1850 would indicate an imminent invasion of crops by locusts (Owusu 2010). According to Mwaura (2008), many people of Africa use indigenous knowledge on insects’ behavior, such as grasshoppers, to protect forests used for rituals, i.e., forests that have trees or animals considered sacred or totems.

Grasshoppers are one of the more diverse taxa in the world (Zhang 2011). While some species are harmful, many are not, but all grasshopper species are a crucial link in food chains (Badenhausser 2012), playing an important role in the recycling and equilibrium of natural ecosystems (Hao et al. 2015). The decline in grassland bird species has been shown to have a positive correlation with an increase in grasshopper densities (Bock et al. 1992). Grasshoppers are a major component in the diet of grassland birds, and studies have shown that there is a direct decrease in birds when grasshoppers are less abundant (Bock et al. 1992). Grasshoppers are also an important food source for other fauna in grassland ecosystems (Latchininsky et al. 2011), such as shrews, moles, bats, armadillos, and anteaters (Srivastava et al. 2009). They are also a food source for many people in the world (Paul et al. 2016). Several authors have reported that grasshoppers and crickets, especially Hieroglyphus africanus Uvarov, 1922, Acanthacris ruficornis citrina (Serville, 1838), Zonocerus variegatus (Linnaeus, 1758), Ornithacris cavroisi (Finot, 1907), Brachytrupes membranaceus (Drury, 1770), Oxya cyanoptera Stal, 1873, Cyrtacanthacris aeruginosa (Stoll, 1813), Ornithacris turbida (Walker, 1870), and Anacridium melanorhodon (Walker, 1870), are the insects predominantly eaten by humans in Nigeria, Cameroon, Benin, and in many other parts of Africa because of their high protein content (Banjo et al. 2006, Riggi et al. 2013, Meutchieye 2019, Zabentungwa et al. 2020). According to De Conconi and Moreno (1988), grasshoppers are also used by many people throughout the world in the preparation of traditional medicines used to cure certain diseases; Sphenarium spp., Taeniopoda sp., and Melanoplus sp. are used to treat kidney diseases and intestinal sickness. Nevertheless, most of the indigenous knowledge on grasshoppers has not been documented and remains the secret of the local populations of Africa, especially in Cameroon. The aim of this study is to assess the indigenous knowledge and perception of communities of South Cameroon on the local forest grasshoppers, especially as it pertains to (1) the use of grasshopper diversity to predict the level of forest degradation; (2) pest grasshoppers, damage to crops, and known and/or used methods to control these pests; and (3) use of grasshoppers in medicine, culture, and as a food source.

Study site.—This study was conducted in villages in the forest areas of the southern Cameroon plateau (between 3°27'N, 11°32'E and 4°10'N, 11°49'E). This area covers almost 42% of Cameroon and is a vast plateau of about 650 m a.s.l., belonging to a strip of plateau that forms the north and west edges of the Congo basin (Westphal et al. 1981). It is dominated by a Guinean climate with four seasons: a long dry season (mid-November to March), a short rainy season (April to June), a short dry season (July to August), and a long rainy season (September to mid-November). Precipitation ranges from 1500 to 2000 mm per year (Santoir and Bopda 1995). These forests are characterized by the dominance of Sterculiacae and Ulmacae, which have great expansion potential, with the undergrowth being invaded by herbaceous plants such as Maranthacae and Acanthacae (Westphal et al. 1981). In these ecosystems, the forest cover is not uniform, as it is regularly degraded because of the economic exploitation of wood and the practice of slash and burn agriculture. The resulting vegetation after degradation are the less diversified fallowlands, dominated by Chromolaena odorata (L.) R.M.King & H.Rob., 1970, Ageratum conizoides L., 1753, Synedrella nodiflora (L.,) Gaertn, and Imperata cylindrica (L.) P.Beauv. Plantain and cocoyam, cassava, yam, maize, and groundnuts are the main food crops (Westphall et al. 1981), while industrial crops include cocoa, coffee, sweet banana, and oil palm (Santoir and Bopda 1995). In the southern Cameroon plateau, our surveys were conducted in four regions (Center, South, East, and Littoral) with the following eight divisions: Mbam and Inoubou (villages investigated: Tchekos, Biabetom, Bokito, Dang, Bygna, and Goufe), Mbam and Kim (village investigated: Ngoro), Mefou and Akono (villages investigated: Ongot and Ngoumou), Nyong and Kelle (villages investigated: Memel, Elale, and Bof Makak), Mvilla (villages investigated: Adoum, Mekam, Mang, Djop, and Biyeyem), Valley of Ntem (villages investigated: Ngutadjap, Aloum, Meko, Akonangui, and Olamze), Sanaga Maritime (village investigated: Ngambe), and High Nyong (village investigated: Ngoyla) (Fig. 1).

Fig. 1. 

Study sites in Cameroon.

Surveys and data analysis.—A total of 341 people were interviewed individually in the 24 villages selected. Rapid rural appraisal methods (RRA) (Chambers 1981, Polidoro et al. 2008, Sattout et al. 2008) were used between January and July 2017; interviews were conducted using a semi-structured survey form. Thirty-one questions were asked to each participant: two questions about personal information (origin, age, sex, and background); eleven questions on the respondents’ general knowledge of grasshoppers, the influence of forest degradation on grasshopper diversity, and on the potential use of these insects to trace the disruption level of forests due to human activities; nine questions on harmful grasshoppers and the methods used to control pest species; and nine questions on the importance of grasshoppers to the local population as a food source or for commerce, medicine, traditional rites, and magic (See supplementary file). The interviews were done in French or in the common language of the area with the help of a local translator. Assessment of the recognition of grasshopper species by the local people was facilitated by the use of pictures of many species from the area around the villages. All frequencies (calculated using EXCEL version 2016) were compared using the Chi² found using the Kruskal-Wallis test in PAST version 4.03 (Hammer et al. 2001). The Mann-Whitney test was used with the same software for two samples. Differences were considered significant at a probability less than 0.05.

Our data allow an assessment of the perception of grasshoppers by local people in Southern Cameroon, particularly in terms of food, health, and landscape conservation. Grasshoppers are known to be herbivore insects common to grassland ecosystems worldwide (Lockwood et al. 2000, Branson et al. 2006). Most of the respondents interviewed (99.7%) thought grasshoppers were found in all landscapes.

Our study shows that the local people understand that the abundance of grasshoppers increases with the degradation or opening of forests: grasshoppers were reported to be rare in pristine forests and abundant in much degraded forests, which is consistent with Badenhausser’s (2012) conclusion that abundance increases with environmental degradation. According to Latchininsky (1996), in the ex-USSR, some forest Orthopteran species (especially Tetrix tartara subacute Bey-Biento, 1951, Acrida oxycephala (Pallas, 1771), Duroniella gracilis Uvarov, 1926, Duroniella kalmyka (Adelung, 1906), and Mesasippus kozhevnikovi iliensis Mistshenko, 1951) become rare after forest degradation; this author noted an increase in grassland species in the degraded areas, especially of Sphingonotus maculatus Uvarov, 1925, Sphingonotus halocnemi Uvarov, 1925, Sphingonotus satrapes Saussure 1884, and Sphingoderus carinatus (Saussure, 1888). Hao et al. (2015) suggested that, apart from steppes and deserts, the abundance of grasshoppers was almost the same in other ecosystems. Unlike our work, Joshi et al. (1999) reported that in India, species diversity and richness were higher in less disturbed sites, followed by replanting environments and severely disturbed environments. These differences show that the behavior of grasshoppers related to the opening of the environment depends on the eco-climatic zones and the structure of the vegetation. The changes to ecosystems strongly affect grasshoppers’ behavior, as grasshoppers use plants as both food and habitat (Latchininsky et al. 2011, Oumarou Ngoute et al. 2020). The challenge is to predict the potential responses of the grasshoppers, in a given ecosystem, to global environmental change.

The respondents said grasshoppers were present in all climatic seasons, but more abundant during the dry seasons. Kijazi et al. (2013) claimed that indigenous peoples in Nigeria used insect abundance and movement to predict the onset of the dry season, and Joshua and Jürgen (2013) reported that the appearance of the bushcricket Ruspolia baileyi Otte, 1997 is known to indicate the dry season in western Uganda. Poubom et al. (2005) and Oladele et al. (2014) recorded the abundant activity of Z. variegatus during the dry seasons in Cameroon and Nigeria.

In general, respondents recognized grasshoppers as being both useful and harmful. They reported that all species consume crops, but only Z. variegatus was recognized as a pest with economic impact. According to Poubom et al. (2005), the majority of farmers in Cameroon consider insects to be pests, and after the green mite Mononychellus tanajoa (Bondar, 1938), it is the stinky grasshopper Z. variegatus that is responsible for most of the damage observed on crop leaves, especially during the dry seasons. The farmers inthe study said that Z. variegatus is a polyphagous pest and that its damage has increased over the past 10 years as forest destruction has increased (Poubom et al. 2005). Oladele et al. (2014) found that in Nigeria, grasshoppers were reported as the main pest followed by beetles and butterflies; the grasshopper Z. variegatus is known to be polyphagous in this area and can devastate fields of vegetables during the dry season. In the same country, Okunlola and Ofuya (2010) reported that Z. variegatus is the third most frequent crop pest after Dysdercus superstitiosus (Fabricius, 1775) (Hemiptera) and Sylepta derogata (Fabricius, 1775) (Lepidoptera).

Our data reveal that the villagers felt that insecticides were the most effective method to control pest grasshoppers, but because of the high cost of chemical insecticides, most farmers used weeding and picking by hand; biological and ecological methods were not mentioned. Worldwide, most locust and grasshopper management programs still rely on chemical pesticides (Zhang et al. 2019). Suggested products, pros and cons, and doses are regularly made publicly available by the FAO Pesticide Referee Group (FAO 2014). In recent years, a very remarkable advance has been the use of bio-pesticides, prepared with the fungus Metarhizium acridum, as important components of management programs and with good efficacy (Zhang et al. 2019). However, in our study, traditional methods of grasshopper control were the most used, which is consistent with the results of Joshua and Jürgen (2013), who reported that the majority of African farmers still depended on indigenous pest management approaches. In Nigeria, according to Oladele et al. (2014), 76.7% of farmers use cultural or traditional methods due to the unavailability and high cost of chemical insecticides. In the same country, Okunlola and Ofuya (2010) found that 76% of farmers were aware of indigenous methods for the control of vegetable pests. Our study shows that the most-used traditional methods were spraying smoke and spreading ash and litter on crops. Respondents reported that smoke can be up to 75–100% effective in repelling grasshoppers, but the control of Z. variegatus comes down to hand picking and human consumption. Poubom et al. (2005) reported that in most regions of Cameroon, the traditional methods of grasshopper control were manual collection or capture of edible species that provide additional food for families. Some local people in southern Cameroon collect grasshopper species (mainly Z. variegatus) as a food source for poultry. Page (1978) recommends plowing to control Z. variegatus. When females have laid their eggs in clumps in the soil, plowing brings the eggs to the surface and causes them to dry out. If this practice was adopted by all farmers, populations of Z. variegatus may be greatly reduced and damage minimized (Modder 1994). In Uganda, the natives use extracts of natural plants to control crop pests, specifically Capsicum frutescens L., 1753, Tagetes spp., Nicotiana tabacum L. 1753, Cypressus spp., Tephrosia vogelii Hook.f., 1849, Azadirachta indica A.Juss., 1830, Musa spp., Moringa oleifera Lam., 1785, Tithonia diversifolia (Hemsl.) A.Gray, 1883, Lantana camara L., 1753, Phytolacca dodecandra L’Her., Vernonia amygdalina Delile, Aloe spp., Eucalyptus spp., Cannabis sativa L., 1753, Coffea sp., and Carica papaya L., 1753 (Joshua and Jürgen 2013). Extracts with insecticidal properties come from the roots, stems, leaves, or flowers of these plants; they have a low spectrum of action, are easily usable, and have few residues capable of accumulating in animal or plant tissues. However, many farmers have reported that some botanical formulations take a long time to prepare and are not easy to apply, especially on a large scale (Mugisha-Kamatenesi et al. 2008).

Most of the respondents (85.9%) in our study said grasshoppers are used as food in addition to Tettigonidae and Gryllidae, and the grasshopper species consumed by the local people are Z. variegatus and O. spissus. Orthoptera species are used as food in many parts of the world, such as Australia, India, South America, and Africa (van Huis 2003, Srivastava et al. 2009, Mitsuhashi 2016, Niassy et al. 2016, Jongema 2017, Tchibozo and Lecoq 2017). Gullan and Cranston (2010) reported that most of the edible insects used worldwide come from a relatively small number of orders, including crickets, grasshoppers, and locusts. According to Riggi et al. (2013), Coleoptera are the most commonly consumed, and Orthoptera are the second group of insects consumed in Africa, specifically grasshoppers such as Hieroglyphus africanus Uvarov, 1922, Acanthacris ruficornis citrina (Serville, 1838), Ornithacris cavroisi (Finot, 1907), locusts [Locusta migratoria (Linnaeus, 1758)], and crickets [Brachytrupes membranaceus (Drury, 1773)] which have a nutritional quality superior or similar to that of the meat products currently available. Insects as food are not inferior to other sources of protein, such as other animals or plants (Xiaoming et al. 2010). A recent analysis of the nutrient composition of Z. variegatus from Nigeria showed high values of protein, crude lipids, and minerals (potassium, sodium, and calcium) (Anaduaka et al. 2021). Our study shows that Z. variegatus and O. spissus are also sold in the markets. Bronwyn (2013) noted that grasshoppers are eaten and sold in the markets of Dimapur and Kohima, India: the legs, wings, and viscera are removed, and they are fried in oil with ingredients such as onion, bamboo, ginger, and salt. Pemberton and Yamasaki (1995) reported that grasshoppers appear on restaurant menus in Japan.

Zonocerus variegatus, Atractomorpha acutipennis, and Oxycatantops spissus are used by local people to treat spleen pain, burns, tuberculosis, angina, malaria, stomachaches, and anal tingling. Grasshoppers are considered to have therapeutic value in Australia, India, South America, and Africa (Srivastava et al. 2009). De Conconi and Moreno (1988) reported that most of the insects (such as grasshoppers and locusts) sold in the markets in Mexico are also used as diuretics, analgesics, anesthetics, or aphrodisiacs. The species Sphenarium spp., Taeniopoda sp., and Melanoplus sp. are used to treat kidney diseases and intestinal disorders (the hind legs of grasshoppers are crushed and mixed with water, then drunk as a powerful diuretic). Locusts of the species Schistocerca spp. are helpful in cases of postnatal anemia and in pulmonary diseases, asthma, and chronic cough. The legs of the crickets Acheta domesticus (Linnaeus, 1758) are crushed and mixed with water and drunk as a diuretic for dropsy edema (De Conconi and Moreno 1988). Lawal and Banjo (2007) reported that the grasshoppers Z. variegatus and Zabalius lineolatus (Stal, 1873) are used to treat childhood illness and injuries in Nigeria. Some species are involved in the magic and mystical treatment of diseases in Mexico: Brachytrypes sp. crickets are used to treat bleeding in women before delivery (De Conconi and Moreno 1988).

All these examples demonstrate that, as in many regions of the world, diverse use is made of grasshoppers in southern Cameroon, whether as a food source, remedies, or as indicators of environmental change. In addition, numerous local solutions (of varying effectiveness) are used to control pest species. It is important to continue to identify, understand, and develop this traditional knowledge as a possible source or at least partial solution to some of the environmental changes currently underway.

This work was partially made possible by a Rufford Small Grant (ID application: 19665-1) from the Rufford Foundation: we did the surveys during our sensitizations against deforestation in the divisions of Mefou and Akono, Valley of Ntem, and Mvilla. We warmly thank all the inhabitants interviewed during our field trips for their cooperation. We also thank Mrs Guy Raoul Saroua, Ngan, Joseph Romuald Fotso Njonkam, Martin Lutter Nkoulou, Annette Friede Hell, and Maurice Nkoulou, who helped in the survey in the divisions of Valley of Ntem, Nyong and Kelle, Mbam and Inoubou, High Nyong, and Sanaga Maritime.