Moïse Adamou’s research while affiliated with University of Ngaoundéré and other places

Synthetic pesticides present risks of pollution of the environment, humans and livestock and the alternative proposed today is to use botanical extracts in the fields against crop pests. But in North Cameroon, little information exists concerning the effect of these extracts on useful pollinating insects in general and no information exists in particular on foragers of the genus Amegilla Friese, 1897 (Apidae: Apinae: Anthophorini). The frequency and foraging activities of Amegilla , on newly blooming flowers of Vigna unguiculata (L.) Walp., 1843 (Fabales: Fabaceae) were recorded during five consecutive days in 2021 and 2022 planting campaigns. Plants were divided into untreated plots and plots treated using the synthetic insecticide Parastar (l p.c..ha^-1) or 10%, 20% and 30% aqueous leaf extracts of Calotropis procera (Aiton) Aiton, 1811 (Gentianales: Apocynaceae), Eucalyptus camaldulensis Dehnh., 1832 (Myrtales: Myrtaceae) and Tithonia diversifolia (Hemsley) Gray, 1883 (Asterales: Asteraceae) respectively. Among 8,987 insects collected (48.9% in 2021), Amegila calens Le Peletier. 1841 with stockier foragers (2021 campaign: 2.2% of the total collection, entomophily F _{A. calens} =4.5%; 2022 campaign: 0.7%, F _{A. calens} =1.3%; pooled campaigns: 2.9%, F _{A. calens} =2.9%) and Amegilla sp. with slender foragers (2021: 3.8%, F _{Amegilla sp.}=7.7%; 2022: no data) were recorded. Foragers started activity from 6 a.m. and stopped foraging before noon, with a peak of activity in 8 to 9 a.m. time slot for A. calens and 10 to 11 a.m. time slot for Amegilla sp.. During the five consecutive days from the first blooming day of the flowers, 598 visits (89.8% in 2021 and 10.2% in 2022) were recorded with a peak of visits during the 3^rd day and then declined until it stopped during the 5^th day. Treatments including the synthetic insecticide (which was the most repellent to the wild bees), did not significantly reduce the frequency of visits. But 20% aqueous extract of Ca. procera showed a significant increased of the mean duration of visits of the bees, compare to the results recorded in Parastar-treated plots. Therefore, the tested extracts, especially 20% aqueous leaves extract of Ca. procera may be recommended to control field insect pests and for preservation of foraging activities of Amegilla genus.

Synthetic pesticides present worldwide risks of contamination of humans, livestock and the environment due to the strong persistence and the toxic residues in fruits and vegetables. Natural biopesticides of local plant origin present low persistence and are the best alternative for the control of crop pests. In the Adamaoua region (Northern Cameroon), few studies exist concerning effects of botanical pesticides on the behavior of beneficial insects. Studies aimed to draw up a list of pollinating insects on flowers of Vigna unguiculata (L.) Walp., 1843 (Fabales: Fabaceae), in situations of treatment with botanical pesticides compared to the situation of the use of synthetic insecticide and to determine the effect of the biopesticides on the behavior of the main floricultural insects. Field investigations were carried out during two cowpea cultivation campaigns (June to September 2021 and June to October 2022) in Dang (suburb of Ngaoundere) on the effect of leaves extracts of local plant origin on the foraging behavior of Apis mellifera Linnaeus, 1758 (Hymenoptera: Apidae) and the main sap-sucking insect Aphis craccivora Koch, 1854 (Hemiptera: Aphididae). Forty-four cowpea plots of 4x3.5 m each distributed according to the randomized complete block model (four untreated plots as negative control, four plots treated with the synthetic insecticide Parastar (40EC 535/ 10/IN, 20 g/l of imidacloprid and 20 g/l of lamda-cyhalothrin) as positive control, and 36 experimental plots treated with three concentrations (10%, 20% and 30%) of aqueous leaves extract of Calotropis procera (Gentianales: Apocynaceae), Eucalyptus camaldulensis (Myrtales: Myrtaceae), and Tithonia diversifolia (Asterales: Asteraceae) respectively, made it possible to conduct four treatments: (1) flowers left to freely pollination, (2) flowers protected against pollinators, (3) flowers visited exclusively by Ap. mellifera and (4) flowers protected against insects. Among eight species (four orders, four families and seven genera) recorded on the flowers of V. unguiculata , the domestic bee Ap. mellifera was the most common and collected nectar and pollen. The control plots and those treated with 10% or 20% aqueous leaves extracts allowed the bee to carry out its activity. Plots treated with 30% extract of each plant and those treated with the synthetic insecticide Parastar, drastically altered the rhythm and speed of activity in Ap. mellifera foragers. This behavior became less coordinated and slow on treated plants. It would be wise to use 10% or 20% aqueous extracts as botanical insecticides and an alternative to the synthetic insecticide Parastar.

The impact of aqueous extracts from the leaves of Callistemon rigidus, Lippia multiflora and Plectranthus glandulosus on the foraging behavior of Apis mellifera on Glycine max flowers were evaluated in Ngaoundéré Cameroon, during two successive agricultural seasons. The search was conducted in 1064 m2 experimental field with treatments arranged in a completely randomized blocks design 4 times replicated: 1 control x 3 plants x 3 extracts x 3 concentrations (5%, 10% and 15%) x 1 standard synthesis insecticide (Decis) x four groups of flower buds (group 1: flowers free to insect visits; group 2: flowers protected from insects using gauze bags; group 3: protected flowers and opened exclusively to A. mellifera and group 4: protected flowers opened from time to time without any visit of insects or other organisms). This Fabaceae was visited by nine species of insects of which the honeybee, A. mellifera was the most numerous (> 90%) and exclusively collected nectar. The different insecticides tested were attractive to this pollinating insect, specially at the concentration of 15%. The mean duration visit of this bee varied from 1.9 sec on the plots treated with Decis to 4.4 sec on the plots treated with 15% C. rigidus. The fruiting indices were 0.96, 0.69, 0.94 and 0.67 respectively for flowers of group 1, 2, 3 and 4. Callistemon rigidus at the content of 15% significantly improved the fruiting rate compared to the other treatments. According to this study, it would be wise to use aqueous extracts at 15% concentrations to improve the pollinating activity of A. mellifera in order to improve seed yield.

Cowpea plants are damaged by insects in North-Cameroon. During ecological survey (2021 and 2022) in 44 plots of 4x3.5 m each, insects were captured on stems, leaves, flowers and pods, stored in vials containing 70° alcohol, identified in laboratory and the community structure was characterized. We captured 26,015 adults belonging to six orders, 13 families, 19 genera and 19 species. Coleoptera, Hemiptera and Hymenoptera were species-rich orders [five species each (26.3%)]. Hemiptera was mostly abundant (40.0%) followed by Coleoptera (27.6%), Hymenoptera (21.9%), Lepidoptera (0.9%). Heteroptera and Orthoptera were least abundant (0.8% respectively). We recorded five (26.3%) useful species [the West African predator species Cheilomenes sulphurea (Coleoptera: Coccinellidae), and four (21.1%) afrotropical Apidae species [Apis mellifera adamsonni, Amegilla calens, Amegilla sp. and Xylocopa olivacea]], seven (36.8%) phytophagous species [the indomalayan native Aulacophora indica (Coleoptera: Chrysomelidae), Nearctic native Danaus plexippus (Lepidoptera: Nymphalidae), Palaearctic native Dolerus sp. (Hymenoptera: Tenthredinidae), afrotropical native Hypolimnas misippus (Lepidoptera: Nymphalidae), afrotropical native Monolepta marginella (Coleoptera: Chrysomelidae), Palaearctic native Phyllotreta cruciferae (Coleoptera: Chrysomelidae) and the Eurasian native Tettigonia viridissima (Orthoptera: Tettigoniidae)]. We recorded seven (36.8%) sap-feeding species [the afrotropical native Anoplocnemis curvipes (Hemiptera: Coreidae), cosmopolitan Palaearctic native Aphis crassivora (Hemiptera: Aphididae), old world native Bothrogonia sp. (Hemiptera: Cicadellidae), subtropical native Dysdercus cingulata (Hemiptera: Pyrrhocoridae), western Palaearctic native Lagria hirta (Coleoptera: Tenebrionidae), North American native Poecilocapsus sp. (Hemiptera: Miridae) and the Palaearctic native Riptortus dentipes (Heteroptera: Alydidae)]. Giving up eight (42.1%) native species, 11 (57.9%) non-native species and 14 (73.7%) pest species [three natives species (15.8%) and 11 non-natives species (57.9%)]. The abundant species were M. marginella (39.9%), Poecilocapsus sp. (14.4%), Au. indica (11.4%), Ph. cruciferae (10.4%), C. sulphurea (4.6%), H. misippus (3.7%), L. hirta (3.4%), Ah. crassivora (2.4%) while 11 species (57.9%) were rare (<2.2% each). Insects associated with cowpea consisted mostly of non-native species and the situation calls for more research on the bio-ecology of recorded pests. Cowpea plants' insect assemblage mostly presented in 39 Moukhtar Mohammadou et al.: Diversity and Abundance of Pest Insects Associated with Vigna unguiculata (L.) Walp., 1843 (Fabales: Fabaceae) in Bockle and Dang Localities (North-Cameroon) Bockle and Dang, a fairly significant regeneration force (Zipf and Zipf-Mandelbrot functioning models) and all conditions combine to soar. Due to the numerical and behavioural dominance of non-native insects, a significant number of resources are potentially exploitable. In due course, once the invaders would monopolize available resources and saturate the localities, they would not allow native species the niche opportunities to re-establish themselves. The consequences of loosing native species, which may well interact with the endemic flora and fauna, will be of extreme concern.

Aims: Because of the problems in agroecosystems following the anarchic use of synthetic insecticides, studies propose an alternative, the use of botanical biopesticides against pests. Study Design: The present study was conducted to evaluate (1) the potential of leaf extract of Calotropis procera (Gentianales: Apocynaceae), Eucalyptus camaldulensis (Myrtales: Myrtaceae) and Tithonia diversifolia (Asterales: Asteraceae) against insects and (2) impact of Apis mellifera (Hymenoptera: Apidae) on Vigna unguiculata (Fabales: Fabaceae) seed yield in North Cameroon. Place and Duration of Study: A field study was set up in 2021 in North Cameroon, during the rainy season. Fourthy four plots of 4x3.5 m each were distributed according to a randomized complete block design model comprising four untreated, four treated using parastar (40EC 535/10/IN, 20 g/l imidaclopride and 20 g/l lamda-cyhalothrine), and 36 plots treated using 10%, 20% and 30% aqueous leaf extracts separately sprayed against Aphis craccivora (Hemiptera: Aphididae). Methodology: Four groups of flowers were randomly selected: (1) free, (2) protected from insects, (3) free exclusively to Ap. mellifera and (4) protected against insects. Results: A total of 10,984 captured flower insects belonged to three orders (Hemiptera, Hymenoptera and Lepidoptera), three families (Aphididae, Apidae and Nymphalidae) and seven species [one (14.3%) sap-sucking Aphis craccivora (Hemiptera: Aphididae), four (57.1%) pollinators Hymenoptera Apidae [Amegilla calens, Amegilla sp., Apis mellifera and Xylocopa olivacea] and two (28.6%) Lepidoptera Nymphalidae [Danaus plexippus and Hypolimnas misippus]. A total of 7,425 insects associated with V. unguiculara corresponded to four orders [Hemiptera (56.7%), Coleoptera (41.5%), Heteroptera and Orthoptera with 0.9% respectively], nine families [Aphididae (45.3%), Chrysomelidae (38.7%), Pyrrhocoridae (4.8%), Coreidae (3.8%), Cicadellidae (2.8%), Coccinellidae (1.9%), Alydidae, Tenebrionidae and Tettigoniidae with 0.9% respectively], 11 genera and 11 species. Conclusion: Apis mellifera was the major pollinator and Aphis crassivora the major pest. The seed yield was improved by 30% extract of plants without impact on pollinators.

There is a frightening decline in the population pollinators around the world due to the over usage of synthetic pesticides, leading to the directly reduce of plant production. Plant extracts with insecticidal properties could be eco-friendly alternatives to synthetic pesticides in maintaining the pollinator population and the diversity of the ecosystem. The impact of aqueous extracts of Cassia occidentalis L., Eucalyptus camaldulensis Dehnh. and Hyptis suaveolens L. was investigated on the entomofauna and the seed yield of Gossypium hirsutum L. cotton. The study was carried out in RCBD, four times replicated: 3 extracts x 1 standard synthetic insecticide (TEMA) x 1 control x 4 groups of flowers (group 1: flowers free to insect visits, group 2: flowers protected from insects using gauze bags, group 3: protected flowers and opened exclusively to Amegilla sp. and group 4: protected flowers opened from time to time without any visit of insect). Gossypium hirsutum was found to be visited by the insects belonging to five orders, 10 families and 18 species. Amegilla sp.1 and Apis mellifera were the major pollinators during the rainy and dry seasons, respectively. The number and quality of seeds visited exclusively by Amegilla sp.1 were significantly improved by H. suaveolens extract. During the dry season, E. camaldulensis and H. suaveolens extracts as well as the standard insecticide improved the number of seeds and the percentage of normal seeds harvested from the flowers allowed to be visited by insects; that was probably due to their insecticidal effects which protected plants from pest damage. Therefore, aqueous extracts of E. camaldulensis and H. suaveolens are good candidates for incorporation in integrated pest management programs to minimize the risk of synthetic pesticides to pollinators, hence to increase the yield and the quality of seeds.