Entomofaunal diversity in cowpea [Vigna unguiculata (L.) Walp.] cultivation systems within the cotton-growing zone of central Benin

J. Biodiv. & Environ. Sci. Zadji et al. RESEARCH PAPER OPEN ACCESS Entomofaunal diversity in cowpea [ Vigna unguiculata (L.) Walp.] cultivation systems within the cotton-growing zone of central Benin Lionel Zadji*1, Roland Bocco2, Mohamed Yaya1, Abdou-Abou-Bakari Lassissi1, Raphael Okounou Toko1 1Department of Science and Technics of Plant Production, Faculty of Agronomy, University of Parakou, Bénin 2Texas AgriLife Research and Extension Center, Texas A&M System, 1509 Aggie Dr., Beaumont, TX 77713, USA Key words: Cowpea, Insect fauna, Sampling, Pests, Functional groups DOI: https://dx.doi.org/10.12692/jbes/27.2.21-34 [ Published: August 08, 2025 ] ABSTRACT Cowpea productivity in Benin remains low, largely due to multiple constraints—chief among them, insect infestations. Despite this, few studies have comprehensively examined the insect fauna associated with cowpea, limiting the development of targeted and effective management strategies. This study addresses the gap by investigating the entomofaunal diversity within cowpea cropping systems in the Central Benin cotton zone. Field sampling was conducted during the rainy season, from July to October 2024, across three distinct sites. The methodology included direct observations, insect collection from plants, and the use of buried traps. A total of 79 insect species, spanning 73 genera and 37 families across seven orders, were identified. The most represented were Hemiptera (34%), Coleoptera (25%), Lepidoptera (16%), Diptera (10%), Thysanoptera (6%), Orthoptera (5%), and Hymenoptera (3%). Biodiversity indices—Shannon (2.78 - 2.81), Equitability (0.67 - 0.80), and Simpson (0.91) — indicate a high level of species diversity, with a slight dominance of individuals from a few key families. These included Chrysomelidae, Crambidae, Aphididae, Coreidae, Cicadellidae, Agromyzidae, and Thripidae. Analysis of functional groups across cowpea phenological stages revealed a marked predominance of pest species over beneficial insects throughout the crop cycle. These findings highlighted the rich insect biodiversity within cowpea ecosystems in central Benin, while also underscoring a functional imbalance driven by pest dominance. The results advocate for integrated management strategies that prioritize the conservation of beneficial insects and the continuous monitoring of pest populations to enhance cowpea productivity. *Corresponding Author: Lionel Zadji  lioncea[email protected]r Journal of Biodiversity and Environmental Sciences | JBES ISSN: 2220-6663 (Print); 2222-3045 (Online) Website: https://www.innspub.net E-mail contact: [email protected] Vol. 27, Issue: 2, p. 21-34, 2025 J. Biodiv. & Environ. Sci. Vol. 27, Issue: 2, p. 21-34, 2025 22 Zadji et al. Journal of Biodiversity and Environmental Sciences | JBES Website: https://www.innspub.net INTRODUCTION Cowpea (Vigna unguiculata L.), is a grain legume of the Fabaceae family native to Africa (Houenou et al., 2022). It adapts to the climatic and edaphic conditions of most countries in Africa and elsewhere (Gbaguidi et al., 2015). Today, it is grown in almost all tropical and subtropical regions for human food and livestock feed. All parts of the plant are used, including the seeds, green pods, and leaves (Boukar et al., 2019). It is the main legume in Africa, accounting for approximately 94% of the global production, most of which comes from the western and central parts of the continent (FAO, 2017). In Benin, it is the most important grain legume. Its production decreased by 13.6% from 2022 to 2023 and was estimated to be 122,744 tons in 2023 versus 142,002 tons in 2022 (DSA, 2024). It is mainly cultivated for its seeds, rich in proteins (∼30%) and carbohydrates (50-60%) (Diouf and Hilu, 2005); its leaves, rich in phosphorus (3.0 to 6.7 mg/g), ascorbic acid (0.3 to 1.5 mg/g), and proteins (27 to 35%) (Ahenkora et al., 1998); its important role in cropping systems and in soil fertility management (Omoigui et al., 2018; Houenou et al., 2022); etc. Despite these numerous advantages, the cultivation of cowpea faces numerous production constraints that lead to extremely low yields (25 kg/ha) in farmers' fields in Africa (Kamara et al., 2018), with an average yield of about 600 kg/ha across the continent (FAO, 2017). This value is well below the potential yield of 1500-2500 kg/ha for most improved cowpea varieties in Africa (Kamara et al., 2018). In Benin, cowpea yields ranged between 879 and 961 kg/ha from 2018 to 2023 (DSA, 2024), while its potential yield under favorable conditions can reach 2500 kg per hectare (MAEP, 2016). Cowpea low productivity is due to several biotic and abiotic factors (Boukar et al., 2016). Insect pests are the most important constraint affecting cowpea at all stages of its development up to storage (Sodedji et al., 2022). In the absence of effective control, damage from insect pests can reach 80 to 100% (Ahmed et al., 2009; Dugje et al., 2009). These attacks are particularly severe during flowering and pod sets (Ajao et al., 2016). Efficient control of these insect pests can only be achieved through the development of suitable strategies, including combining methods promoting the establishment of more sustainable agroecological systems (Franke et al., 2018). Knowledge of pests (Choudourou et al., 2012) and auxiliary fauna that participate in pest regulation (Tendeng et al., 2017) and agroecosystem balance (Bello et al., 2018) is the preliminary step to developing sustainable pest management strategies that are eco-friendly and ensure food security (Fatondji et al., 2018). In Benin, very few studies have focused on the cowpea entomofauna’s biodiversity. The information provided by these studies unfortunately remains focused on a single municipality (Bello et al., 2018) and needs to be updated for sustainable management of the main cowpea insect pests. In addition, it has been revealed that pest populations and their natural enemies vary over time with changing agricultural practices and environmental conditions, particularly in the current context of climate change (Skendžić et al., 2021; Eigenbrode and Adhikari, 2023). The current study aims to contribute to knowledge on the diversity of entomological fauna of cowpea in Benin. The information generated should be useful in terms of a perspective of biological or integrated control program development. MATERIALS AND METHODS Study area and sampled sites The study was carried out in Agroecological Zone V (AEZ V) named the Central Cotton Zone, which is one of the eight AEZs in Benin (Aholoukpè et al., 2020) (Fig. 1). Located in the center of Benin, AEZ V covers eleven municipalities (Ouessè, Bantè, Glazoué, DassaZoumé, Savè, Bassila, Parakou, Tchaourou, Aplahoué, and Kétou). The region has a Sudano-Guinean climate, which is characterized by two rainy seasons; however, the northern part exhibits a Sudanese tendency and experiences only one rainy season. The rainfall varies from 600 to 1200 mm of water per year in the West and 1000 to 1400 mm of water per year in the East. The average annual temperature is 26.5°C. The soils are of the leached tropical ferruginous type, more or less concreted (Leptosols and Luvisols), ferralitic with a sandy to sandy-clayey texture (Acrisols), and hydromorphic valleys (Fluvisols). The J. Biodiv. & Environ. Sci. Vol. 27, Issue: 2, p. 21-34, 2025 23 Zadji et al. Journal of Biodiversity and Environmental Sciences | JBES Website: https://www.innspub.net agricultural systems combine food crops (sorghum, yam, cowpea, peanut, maize, and cassava) and cash crops such as cotton (Chevallier et al., 2020). Fig. 1. Map showing the study area and sampled sites Surveys were carried out in three cowpea cultivation sites located in the municipalities of Tchaorou (Konkoma), Bantè (Gbégamè), and Djidja (Komè), as depicted in Fig. 1. These sites were purposefully selected in collaboration with agriculture extension specialists, based on a set of well-defined criteria: a minimum sown area of 1 hectare, a history of at least three consecutive years of cowpea cultivation, ease of access, absence of phytosanitary treatments, and relative isolation from neighboring crops to reduce external influences.. Specifically, the Konkoma site encompassed 1.80 hectares with four years of continuous cowpea production, Gbégamè covered 1.65 hectares with three years of cultivation, and Komè spanned 1.50 hectares with four years of prior cowpea farming. Sampling, sorting and conservation of collected samples Sampling was performed during the cropping season from July to October, 2024. Regular insect captures were carried out starting from twenty-one (21) days after planting and continued at a weekly interval for a total of twelve (12) records. Since insect sampling often requires several techniques to obtain a wide diversity of insects, several techniques were combined to inventory the entomofauna during the cowpea development cycle. The techniques consisted of direct observations and captures on plants (by hand, pliers, sweep net, and mouth aspirator) as well as trapping using buried traps (pitfall traps) (Ndiaye et al., 2023). The collected insects (captured or trapped) were sorted under a binocular loupe and classified according to their orders and families before being preserved in vials containing alcohol at 70˚C. The vials were transferred to the laboratory for further insect identification. Identification of specimens The specimens were identified in the laboratory down to the species level and counted. Identifications were made using a magnifying glass, identification keys, and illustrated catalogues (Delvare and Aberlenc, 1989; Appert and Deuse, 1998; Bordat and Arvanitakis, 2004; Poutouli et al., 2011; Zettler et al., 2016). Data analysis Data on specimen counts (for each order, family, genus, and species) were arranged in an Excel spreadsheet version 2013. Percentages were calculated based on the overall total number of collected specimens. Ecological parameters, including relative abundance (Ra), specific richness (Sr), Shannon-Weaver, Pielou’s equitability, and Simpson indexes, were calculated. Relative abundance Ra (%) refers to the proportion of individuals of a given species (ni) relative to the total individuals (N) recorded across all species. It is calculated using the formula proposed by Dajoz (2006). ( ) Specific richness Sr (%) represents the proportion of species within a particular taxonomic group (Order or Family), denoted as Ri, relative to the total number of species R observed in the study. This metric is calculated using the formula described by McCarthy (2004). ( ) Shannon-Weaver index (H’) is a measure of species richness and diversity, commonly used to assess the complexity of insect communities. It assumes that all species present are included in the sample and that individuals are randomly sampled. The index is J. Biodiv. & Environ. Sci. Vol. 27, Issue: 2, p. 21-34, 2025 24 Zadji et al. Journal of Biodiversity and Environmental Sciences | JBES Website: https://www.innspub.net calculated using the formula provided by Ramade (2009). ∑ ( ) where ni is the number of individuals for species i and N is the total number of individuals collected for all species. Pielou’s equitability index (E) assesses the evenness of species distribution within the families observed. It reflects how uniformly individuals are spread across species. The index is calculated using the formula described by Weesie and Belemsobgo (1997). where H’ = Shannon-Weaver index and H’ max = maximum diversity. H’ max = lnS, with S = total richness expressed in number of families. E ranges from 0 to 1, where 1 indicates perfect evenness (all species equally abundant) and 0 indicates maximum unevenness (one species dominates completely). Simpson’s diversity index (S) quantifies the likelihood that two individuals randomly selected from a sample will belong to different species, thereby reflecting species diversity within a community. The index is calculated using the formula proposed by Simpson (1949). ( ) ( ) where ni is the number of individuals for species i and N is the total number of individuals collected for all species. D ranges from 0 to 1, where high scores (close to 1) indicate high diversity and low scores (close to 0) indicate low diversity. RESULTS Composition and general abundance of sampled insects Table 1 presents the biodiversity of the entomofauna associated with the cowpea crop. In total, 9092 individuals were collected from 79 species, 73 genera, 37 families, and 7 orders. The number of individuals collected is higher in Komè (3183) than in Gbégamè (3098) and Konkoma (2831). Table 1. Relative abundance of families, genera and species of collected insects Orders Families/Genus/Species Komkoma Gbégamè Komè Total Effectif % Effectif % Effectif % Effectif % Coleoptera Coccinellidae 106 3,74 56 1,82 115 3,61 277 3,05 Cheilomones sulphurea (Olivier, 1791) 47 1,66 19 0,62 25 0,79 91 1,00 Epilachna spp. (Dejean, 1837) 59 2,08 37 1,20 90 2,83 186 2,05 Apionidae 20 0,71 16 0,52 23 0,72 59 0,65 Apion miniatum (Germar, 1833) 20 0,71 16 0,52 23 0,72 59 0,65 Scarabaeidae 6 0,21 6 0,19 7 0,22 19 0,21 Pachnoda cordata (Drury, 1773) 6 0,21 6 0,19 7 0,22 19 0,21 Tenebrionidae 7 0,25 0 0,00 0 0,00 7 0,08 Lagria villosa (Fabricius, 1781) 7 0,25 0 0,00 0 0,00 7 0,08 Chrysomelidae 545 19,25 638 20,73 728 22,87 1911 21,02 Ootheca mutabulis (Sahlberg, 1829) 69 2,44 35 1,14 42 1,32 146 1,61 Nisotra uniformis (Jacoby, 1906) 14 0,49 38 1,23 27 0,85 79 0,87 Psylloïdes chrysocephala (Linnaeus, 1758) 9 0,32 0 0,00 0 0,00 9 0,10 Oulema melanopus (Linnaeus, 1758) 0 0,00 2 0,06 1 0,03 3 0,03 Monolepta tenuicornis (Laboissière, 1920) 3 0,11 17 0,55 18 0,57 38 0,42 Medythia quaterna (Fairmaire, 1880) 22 0,78 28 0,91 17 0,53 67 0,74 Asbecesta cyanipennis (Halord 1877) 0 0,00 3 0,10 7 0,22 10 0,11 Lema spp. (Fabricius, 1798) 0 0,00 15 0,49 12 0,38 27 0,30 Exosoma dalmani (Jacoby, 1897) 2 0,07 12 0,39 18 0,57 32 0,35 Acantoscelides obtectus (Say, 1831) 166 5,86 175 5,69 191 6,00 532 5,85 Aulacophora foveicolis (Lucas, 1849) 17 0,60 15 0,49 9 0,28 41 0,45 Podagrica decolorata (Duvivier, 1892) 16 0,57 8 0,26 19 0,60 43 0,47 Callosobruchus maculatus (Fabricius, 1775) 133 4,70 192 6,24 262 8,23 587 6,46 Callosobruchus rhodesianus (Pic, 1902) 94 3,32 98 3,18 105 3,30 297 3,27 Meloidae 8 0,28 5 0,16 9 0,28 22 0,24 Mylabris spp. (Fabricius, 1775) 8 0,28 5 0,16 9 0,28 22 0,24 J. Biodiv. & Environ. Sci. Vol. 27, Issue: 2, p. 21-34, 2025 25 Zadji et al. Journal of Biodiversity and Environmental Sciences | JBES Website: https://www.innspub.net Curculionidae 3 0,11 0 0,00 6 0,19 9 0,10 Myllocerus spp. (Schönherr, 1823) 3 0,11 0 0,00 6 0,19 9 0,10 Orthoptera Tettigoniidae 12 0,42 18 0,58 10 0,31 40 0,44 Tettigonia viridissima (Linnaeus, 1758) 12 0,42 18 0,58 10 0,31 40 0,44 Acrididae 19,00 0,67 13,00 0,42 16,00 0,50 48,00 0,53 Acrida ungarica (Herbst, 1786) 10 0,35 9 0,29 16 0,50 35 0,38 Cantantops spp. (Schaum, 1853) 9 0,32 4 0,13 0 0,00 13 0,14 Pyrgomorphidae 95,00 3,36 139,00 4,52 112,00 3,52 346,00 3,81 Pyrgomorpha cognata (Charpentier, 1845) 40 1,41 60 1,95 47 1,48 147 1,62 Zonocerus variegatus (Linné, 1758) 55 1,94 79 2,57 65 2,04 199 2,19 Gryllidae 13,00 0,46 19,00 0,62 0,00 0,00 32,00 0,35 Brachytrupes membranaceus (Drury, 1770) 13 0,46 19 0,62 0 0,00 32 0,35 Hymenoptera Vespidae 6,00 0,21 21,00 0,68 10,00 0,31 37,00 0,41 Vespula spp. (Thomson, 1869) 6 0,21 21 0,68 10 0,31 37 0,41 Eulophidae 20,00 0,71 35,00 1,14 23,00 0,72 78,00 0,86 Entedon senegalensis (Rasplus, 1990) 3 0,11 7 0,23 4 0,13 14 0,15 Pediobius vignae (Hedqvist, 1978) 13 0,46 23 0,75 16 0,50 52 0,57 Aprostocetus spp. (Westwood, 1833) 4 0,14 5 0,16 3 0,09 12 0,13 Eurytomidae 0,00 0,00 21,00 0,68 7,00 0,22 28,00 0,31 Eurytoma sp (Illiger, 1807) 0 0,00 21 0,68 7 0,22 28 0,31 Eupelmidae 5,00 0,18 1,00 0,03 9,00 0,28 15,00 0,16 Eupelmus elongatus (Girault, 1916) 5 0,18 1 0,03 9 0,28 15 0,16 Apidae 29,00 1,02 29,00 0,94 34,00 1,07 92,00 1,01 Apis mellifera (Linnaeus, 1758) 27 0,95 15 0,49 34 1,07 76 0,84 Amegilla spp. (Friese, 1897) 2 0,07 14 0,45 0 0,00 16 0,18 Lepidoptera Lycaenidae 14,00 0,49 41,00 1,33 54,00 1,70 109,00 1,20 Euchrysops malathana (Boisduval, 1833) 14 0,49 41 1,33 54 1,70 109 1,20 Noctuidae 113,00 3,99 22,00 0,71 119,00 3,74 254,00 2,79 Spodoptera littoralis (Boisduval, 1833) 23 0,81 16 0,52 19 0,60 58 0,64 Spodoptera exigua (Hubner, 1808) 21 0,74 3 0,10 13 0,41 37 0,41 Helicoverpa armigera (Hubner, 1808) 69 2,44 3 0,10 87 2,73 159 1,75 Crambidae 318,00 11,23 336,00 10,92 349,00 10,96 1003,00 11,03 Syllepta derogata (Fabricius, 1775) 25 0,88 12 0,39 12 0,38 49 0,54 Maruca vitrata (Fabricius, 1787) 276 9,75 313 10,17 329 10,34 918 10,10 Maruca testulalis (Fabricius, 1787) 17 0,60 11 0,36 8 0,25 36 0,40 Pieridae 2,00 0,07 0,00 0,00 0,00 0,00 2,00 0,02 Eurema sp. (Hübner, 1819) 2 0,07 0 0,00 0 0,00 2 0,02 Tortricidae 28,00 0,99 19,00 0,62 24,00 0,75 71,00 0,78 Cydia ptychora (Meyrick, 1922) 28 0,99 19 0,62 24 0,75 71 0,78 Hemiptera Pentatomidae 85,00 3,00 180,00 5,85 152,00 4,78 417,00 4,59 Pentatoma sp. (Olivier, 1789) 17 0,60 41 1,33 12 0,38 70 0,77 Nezara viridula (Linnaeus, 1758) 32 1,13 12 0,39 63 1,98 107 1,18 Aspavia armigera (Fabricius, 1775) 21 0,74 69 2,24 47 1,48 137 1,51 Dryadocoris sp. (Kirkaldy, 1909) 10 0,35 31 1,01 17 0,53 58 0,64 Holcostethus sp. (Fieber, 1860) 5 0,18 27 0,88 13 0,41 45 0,49 Plataspidae 30,00 1,06 11,00 0,36 25,00 0,79 66,00 0,73 Coptosoma cribraria (Fabricius, 1798) 17 0,60 4 0,13 4 0,13 25 0,27 Brachyplatys testudonigra (De Geer, 1774) 13 0,46 7 0,23 21 0,66 41 0,45 Anthocoridae 1,00 0,04 22,00 0,71 12,00 0,38 35,00 0,38 Cardiastethus exiguus (Poppius, 1913) 1 0,04 22 0,71 12 0,38 35 0,38 Alydidae 128,00 4,52 103,00 3,35 66,00 2,07 297,00 3,27 Riptortus dentipes (Fabricius, 1787) 80 2,83 67 2,18 39 1,23 186 2,05 Mirperus jaculus (Thunberg, 1783) 48 1,70 36 1,17 27 0,85 111 1,22 Pyrrhocoridae 14 0,49 5 0,16 8 0,25 27 0,30 Dysdercus spp. (Guerin-Méneville, 1831) 14 0,49 5 0,16 8 0,25 27 0,30 Coreïdae 159 5,62 169 5,49 253 7,95 581 6,39 Anoplocnemis curvipes (Fabricius, 1781) 62 2,19 89 2,89 102 3,20 253 2,78 Clavigralla tomentosicollis (Stal, 1855) 78 2,76 43 1,40 145 4,56 266 2,93 Leptoglossus australis (Fabricius, 1775) 19 0,67 36 1,17 6 0,19 61 0,67 Hydara spp. (Linnaeus, 1758) 0 0,00 1 0,03 0 0,00 1 0,01 Reduviidae 7 0,25 14 0,45 9 0,28 30 0,33 Rhinocoris albopilosus (Signoret, 1858) 0 0,00 9 0,29 0 0,00 9 0,10 Rhinocoris rapax (Stål, 1855) 4 0,14 5 0,16 1 0,03 10 0,11 Rhinocoris bicolor (Fabricius, 1781) 3 0,11 0 0,00 1 0,03 4 0,04 Phonoctonus fasciatus (Palisot de 0 0,00 0 0,00 7 0,22 7 0,08 J. Biodiv. & Environ. Sci. Vol. 27, Issue: 2, p. 21-34, 2025 26 Zadji et al. Journal of Biodiversity and Environmental Sciences | JBES Website: https://www.innspub.net Beauvois, 1805) Aleyrodidae 143 5,05 111 3,61 168 5,28 422 4,64 Bemisia tabaci (Gennadius, 1889) 143 5,05 111 3,61 168 5,28 422 4,64 Aphididae 278 9,82 254 8,25 187 5,87 719 7,91 Aphis crassivora (Koch, 1854) 236 8,34 208 6,76 146 4,59 590 6,49 Aphis gossypi (Glover, 1877) 42 1,48 37 1,20 22 0,69 101 1,11 Macrosyphom euphorbiae (Thomas, 1878) 0 0,00 9 0,29 19 0,60 28 0,31 Cicadellidae 128 4,52 222 7,21 164 5,15 514 5,65 Cicadella spp. (Latreille, 1817) 23 0,81 55 1,79 75 2,36 153 1,68 Empoasca spp. (Walsh, 1862) 105 3,71 167 5,43 89 2,80 361 3,97 Miridae 4 0,14 2 0,06 19 0,60 25 0,27 Lygus spp. (Hahn, 1833) 4 0,14 2 0,06 19 0,60 25 0,27 Thysanoptera Thripidae 237 8,37 149 4,84 189 5,94 575 6,32 Megalurothrips sjostedti (Trybom, 1908) 222 7,84 127 4,13 186 5,84 535 5,88 Thrips tabaci (Lindeman, 1889) 15 0,53 22 0,71 3 0,09 40 0,44 Diptera Agromyzidae 160 5,65 284 9,23 162 5,09 606 6,67 Melanogromyza bonavistae (Madden, 2009) 3 0,11 24 0,78 7 0,22 34 0,37 Ophiomyia spencerella (Greathead, 1969) 15 0,53 44 1,43 21 0,66 80 0,88 Melanogromyza vignalis (Spencer, 1959) 0 0,00 5 0,16 16 0,50 21 0,23 Liriomyza spp. (Mik, 1894) 142 5,02 211 6,86 118 3,71 471 5,18 Tachinidae 31 1,10 54 1,75 27 0,85 112 1,23 Tachina spp. (Meigen, 1803) 31 1,10 54 1,75 27 0,85 112 1,23 Dolichopodidae 56 1,98 41 1,33 87 2,73 184 2,02 Dolichopus sp. (Latreille, 1796) 56 1,98 41 1,33 87 2,73 184 2,02 Syrphidae 1 0,04 22,00 0,71 0,00 0,00 23,00 0,25 Episyrphus spp. (Matsumura & Adachi, 1917) 1 0,04 22 0,71 0 0,00 23 0,25 Total 2831 100 3078 100 3183 100 9092 100 Fig. 2. Relative abundance of orders Fig. 3. Specific richness of orders Relative abundance and specific richness of orders Fig. 2 presents the overall relative abundance of the orders. It appears that Hemiptera were the most abundant, with 34% of the total number of collected individuals, followed by Coleoptera (25%), Lepidoptera (16%), Diptera (10%), Thysanoptera (6%), Orthoptera (5%), and Hymenoptera (3%). As for the overall specific richness of the orders, the analysis of the Fig. 3 shows that Hemiptera were also the richest with 32.91% of the total number of recorded species, followed by Coleoptera (27%), Lepidoptera (11%), Hymenoptera (10%), Diptera (9%), Orthoptera (5%), and Thysanoptera (3%). Fig. 4. Relative abundance of orders according to sampled sites Fig. 4 presents the overall relative abundance of insects according to sampled sites. Regardless of the sampled site, Hemiptera were the most represented, followed by Coleoptera, Lepidoptera, and Diptera. Hymenoptera remains the least abundant order. J. Biodiv. & Environ. Sci. Vol. 27, Issue: 2, p. 21-34, 2025 27 Zadji et al. Journal of Biodiversity and Environmental Sciences | JBES Website: https://www.innspub.net Relative abundance and specific richness of families In general, among the 37 insect families recorded in the study area, the Chrysomelidae (21.02%) were the most abundant, followed by the Crambidae (11.03%), Diptera (10.17%), Aphididae (7.91%), Agromyzidae (6.67%), Coreidae (6.39%), Thripidae (6.32%), and Cicadellidae (5.65%); the remaining families recorded less than 5% of abundance (Table 1). Furthermore, Konkoma represented all the recorded families, except for Eurytomidae. Komè did not represent the families of Tenebrionidae, Gryllidae, Peridae, and Syrphidae. Similarly, Gbégamè did not represent the families of Tenebrionidae, Curculionidae, and Peridae (Table 1). Fig. 5. Specific richness of families Fig. 5 displays the species richness of the 37 recorded families. The Chrysomelidae exhibited the highest species richness (18%) among all other families, with the Pentatomidae following closely at 6%. The families of Agromizydae, Coreïdae, and Reduividae recorded 5% species richness; those of Crambidae, Aphididae, Noctuidae, and Eulophidae, 4%. Thripidae, Cicadellidae, Pyrgomorphidae, Alydidae, Coccinellidae, Apidae, Plataspidae, and Acrididae hosted 3% of species richness, and the remaining families harvested the lowest species richness (1%). Relative abundance of species Fig. 6 shows the relative abundance of 38 out of the 79 species recorded. The 38 species are those that recorded at least 1% of relative abundance. It was about: Maruca vitrata (10%), Aphis crassivora (6%), Callosobruchus maculatus (6%), Megalurothrips sjostedti (6%), Acantoscelides obtectus (6%), Liriomyza spp. (5%), Bemisia tabaci (5%), Empoasca spp. (4%), Callosobruchus rhodesianus (3%), Clavigralla tomentosicollis (3%), Anoplocnemis curvipes (3%), Zonocerus variegatus (2%), Epilachna spp. (2%), Riptortus dentipes (2%), Dolichopus sp. (2%), Helicoverpa armigera (2%), Cicadella spp. (2%), Pyrgomorpha cognata (2%), Ootheca mutabulis (2%), Aspavia armigera (2%), Tachina spp. (1%), Mirperus jaculus (1%), Euchrysops malathana (1%), Nezara viridula (1%), Aphis gossypi (1%), Cheilomones sulphurea (1%), Ophiomyia spencerella (1%), Nisotra uniformis (1%), Apis mellifera (1%), Cydia ptychora (1%), Pentatoma sp. (1%), Medythia quaterna (1%), Leptoglossus australis (1%), Apion miniatum (1%), Spodoptera littoralis (1%), Dryadocoris sp. (1%), Pediobius vignae (1%), Syllepta derogata (1%). The rest of the species recorded less than 1% of relative abundance (Fig. 6). Fig. 6. Relative abundance of species Index of Shannon-Wiener diversity (H'), Piélou equitability (E) and Simpson of captured insects by sampled site Fig. 7 illustrates the values of the Shannon-Weaver diversity index (H’), Pielou’s equitability index (E), and Simpson’s diversity index (D) across the three J. Biodiv. & Environ. Sci. Vol. 27, Issue: 2, p. 21-34, 2025 28 Zadji et al. Journal of Biodiversity and Environmental Sciences | JBES Website: https://www.innspub.net sampling sites. The Shannon index values were relatively consistent among the sites: Konkoma (2.81), Gbégamè (2.78), and Komè (2.78), indicating comparable species richness. Equitability values varied slightly, with Gbégamè (0.79) and Komè (0.80) exhibiting higher evenness in species distribution, while Konkoma showed a lower equitability value (0.67), suggesting a more uneven distribution of individuals among species. The Simpson index remained constant across all sites at 0.91, reflecting a uniformly high level of species diversity (Fig. 7). Fig. 7. Specific diversity of the insect fauna according to sampled sites Functional groups: Composition and dynamics Collected insects are composed of pests, which are the most abundant (89.98%), and auxiliaries (10.29%). The insect pests are grouped in 26 families, including Apionidae, Scarabaeidae, Tenebrionidae, Chrysomelidae, Meloidae, Curculionidae, Tettigoniidae, Acrididae, Pyrgomorphidae, Gryllidae, Lycaenidae, Noctuidae, Crambidae, Pieridae, Tortricidae, Pentatomidae, Plataspidae, Alydidae, Pyrrhocoridae, Coreïdae, Miridae, Aleyrodidae, Aphididae, Cicadellidae, Thripidae, and Agromyzidae. Beneficial insects are distributed across 11 families, of which 6 are consisted of predators (6.45%)—Coccinellidae, Vespidae, Anthocoridae, Reduviidae, Dolichopodidae, and Syrphidae4 families are parasitoids (2.56%- Eulophidae, Eurytomidae, Eupelmidae, and Tachinidaeand one family composed of pollinators (1.01%- Apidae). The functional group of pest families is marked by a high abundance of Chrysomelidae (21.02%) and Crambidae (11.03%). In the functional group of predator families, the most represented families are Coccinellidae (3.05%) and Dolichopodidae (2.02%). Regarding the functional group of parasitoid families, Tachinidae (1.23%) and Eulophidae (0.86%) are the most dominant. Fig. 8. Dynamic of populations of different insect functional groups Fig. 8 presents the dynamics of insect populations in the different functional groups during the development cycle of the cowpea crop. It is clear from the figure that the dynamic of pest populations reveals greater abundance of pests compared to all the other functional groups during the different phenological stages (vegetative, flowering, and pod formation/maturation). The pest population significantly increased from the vegetative stage to pod formation stage before decreasing slightly during the maturation stage. DISCUSSION Our study identified a total of 79 species, 73 genera, 37 families, and 7 orders associated with cowpea crops. The insect community was dominated by two orders: Hemiptera, followed by Coleoptera, with additional representation from Lepidoptera, Diptera, Thysanoptera, Orthoptera, and Hymenoptera. These findings align with previous studies conducted in similar agroecological contexts. For instance, Mohammadou et al. (2023), in their investigation of pest diversity in cowpea fields in Bockle and Dang Localities (North-Cameroon), reported six major orders, with Hemiptera being the most abundant, followed by Coleoptera, Hymenoptera, Lepidoptera, Heteroptera and Orthopera. Similarly, Bello et al. (2018) documented eight insect orders with cowpea in Northwestern Benin, where Coleoptera was the most dominant, followed by Hemiptera (including both Homoptera and Heteroptera), Lepidoptera, J. Biodiv. & Environ. Sci. Vol. 27, Issue: 2, p. 21-34, 2025 29 Zadji et al. Journal of Biodiversity and Environmental Sciences | JBES Website: https://www.innspub.net Diptera, Hymenoptera, Thysanoptera, and Orthoptera. In Cuba, Santana-Baños et al. (2023) recorded five orders in cowpea agroecosystems, with Coleoptera and Hemiptera showing the highest dominance. Collectively, these early studies corroborate our findings, emphasizing the consistent predominance of Hemiptera and Coleoptera in cowpea-associated insect communities across diverse geographic regions. Furthermore, while Bello et al. (2018) reported 27 insect families in cowpea fields in Djougou (Northwestern Benin), our study identified 37 families, thereby contributing additional insights into the entomofaunal diversity of cowpea ecosystems in Benin. The analysis of the Shannon diversity index (2.78 - 2.81), Pielou’s equitability index (0.67 - 0.80) and Simpson’s index (0.91) reveals a high level of familylevel diversity within the insect community, accompanied by a moderate dominance of individuals from a limited subset of families. The most represented families included Chrysomelidae (Coleoptera), followed by Crambidae (Lepidoptera), Aphididae, Coreidae and Cicadellidae (Hemiptera), as well as Agromyzidae (Diptera) and Thripidae (Thysanoptera). Several species within these families are welldocumented pests of cowpea, contributing to significant crop damage and yield reduction (Gopalakrishnan, 2007; Ali, 2009; Aktar et al., 2009; Dzeme et al., 2010; Sharma et al., 2010; Yadav et al., 2017). These findings emphasize the ecological value of monitoring dominant pest families to inform targeted management strategies in cowpea agroecosystems. The abundance of functional groups recorded at different phenological stages showed pests were significantly more abundant throughout the cowpea cycle compared to beneficial insects (predators, parasitoids and pollinators). This evidence indicates that the higher pest density could be facilitated by lower natural enemy populations (Atuo and O'Connell, 2017). Many factors, including the ecological characteristics of the environment, could explain this low density of natural enemies (Holling, 1961). Indeed, climate change could modify abiotic conditions such as temperature, precipitation, humidity, and wind, which can alter the life cycles of certain predatory insect species and their prey, leading to changes in their behaviors and interactions (Traill et al., 2010; Tylianakis et al., 2014). Among identified insect pests, several species pose a significant threat to cowpea cultivation. Key among these were the legume flower and pod borer Maruca vitrata (Singh et al., 1990); pod-sucking bugs such as Clavigralla tomentosicollis, Mirperus jaculus, Riptortus dentipes, Nezara viridula and Anoplocnemis curvipes (Dabiré, 2001; Pitan and Odebiyi, 2001); the flower thrips Megalurothrips sjostedti (Dabiré, 2001); and the leaf beetle Ootheca mutabilis (Mukendi, 2010). Additionally, seedfeeding insects, including Callosobruchus maculatus, C. rhodesianus, Acanthoscelides obtectus, Melanagromyza vignalis and Ophiomya spencerella (Lienard and Seck, 1994), contribute to post-harvest losses. Sap-sucking pests, notably the shiny black aphid Aphis craccivora (Alavo, 2010), Medythia quaterna and Monolepta tenuicornis, are particularly damaging; the latter two are known vectors of "Cowpea Mottle Virus" (CMeV) on cowpea (Tia, 1987). These findings suggest that the low cowpea yields observed in the country may be largely attributed to the diverse assemblage of insect pests that infest the crop throughout its entire phenological stages. From seedling emergence to pod maturation, these pests exert continuous pressure on cowpea plants, leading to significant damage and substantial yield losses (Yadav et al., 2017). Regarding beneficial insects, predatory insect species have been recorded. These include Cheilomones sulphurea and Episyrphus spp., which are predators of aphids (Soro et al., 2021); Vespula spp., Rhinocoris sp., Phonoctonus fasciatus, Dolichopus sp., and Cardiastethus exiguous feed on a wide range of insect pests belonging to various taxa (Abdurahiman et al., 1982; Donovan, 2003; Sahayaraj and Balasubramanian, 2016). Concerning parasitoids, our study revealed the census of species such as Entedon senegalensis, strictly subjugated to Apions of Vigna (Bapfubusa et al., 1990); Pediobius vignae, whose larvae are parasitoids of cowpea seed-feeder Melanagromyza