Boris Fouelifack-Nintidem’s research while affiliated with University of Douala 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.

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.

Nesting system, diet behaviour, activity rhythm and predatory behaviour of Crematogaster (Nematocrema) stadelmanni Mayr, 1895 were studied in the field situation in suburbs of Douala (Littoral-Cameroon). Polycalic and polydomous nesting system were recorded. Large independent nests were positioned on the bark surface of trunks (50.8%) or the underside bark of the fork of large branches (49.2%) of cultivated or wild trees (45.8% and 54.2% respectively). Workers collected nectar from 18 plants from eight families: Asteraceae, Costaceae, Ehretiaceae, Euphorbiaceae, Mimosaceae Phyllantaceae, Poaceae and Rutaceae. They collected honeydew from Aleyrodidae and four Hemipteran families from Sternorrhyncha suborder: Aphididae, Coccidae Pseudococcidae and Stictococcidae. These Hemipterans proliferated on 11 plant families: Anacardiaceae, Annonaceae, Apocynaceae, Asteraceae, Costaceae, Euphorbiaceae, Myrtaceae, Poaceae, Rutaceae, Solanaceae and Urticaceae. Solid particles brought back to the nest were mostly from plants (72.5%) and weakly preys (27.5%). Sugary liquids were preferred over fats, carbohydrate sources, and even preys. Products were collected continuously (day and night) in the foliage of the host plant and neighbouring plants, shrubs and grasses. Workers occasionally brought back to the nest dead or dying larvae of grasshoppers and small particles of other arthropods (ants, flies, caterpillars). The sequence of behavioural acts recorded during the capture of larvae of Ruspolia differens (Orthoptera: Tettigoniidae) and adults of Zonocerus variegatus (Orthoptera: Pyrgomorphidae) (3 to 5 mm and 15 to 20 mm long respectively) were compared. The main sequence presented succession of seven acts: (1) detection by contact; (2) antennation; (3) attack-seizure; (4) short-range recruitment of nestmates in the vicinity; (5) spread-eagling of preys; (6) cutting up the prey on the spot; and (7) transport of pieces or whole prey to the nest. The stinging phase was not recorded. The duration of the capture of small prey (66 min. to 1 hr. 25 sec.; mean ± se: 1 hr. 57 min. 25 sec. ± 12 min. 2 sec.; 10 essays) was lower than that of large preys (2 hrs. 33 sec. to 4 hrs. 16 sec.; 2 hrs. 58 min. 32 sec. ± 17 min. 15 sec.; 10 essays; Mann-Withney test: T = 72.00; p = 0.014). The long duration American Journal of Entomology 2022; 6(2): 27-42 28 of captures suggested that spread-eagling and cutting up preys on the spot lasted a long time. Cr. stadelmanni is a poor predator indirectly harmful for wild or cultivated trees since their predatory aptitude is low compared to aggressive dominant arboreal-nesting ants and is counterbalanced by the propensity to honeydew.

Fascioliasis and bilharzia occur in the Littoral region of Cameroon. Recent reports indicate a high prevalence of bilharzia in school-age children in the locality of Njombé-Penja, close to the city of Douala. This infectious disease may spread in the near future to the city of Douala, especially if the localities at risk are visited by infected people, who defecate or urinate in streams or swamps as is the habit of populations in populous zones of the city and where environmental cleanliness is not respected. It is known that several molluscs are intermediate hosts of the infectious agents of this pathology but little is known about the snail’s community structure at the coastal zone of the country. The present study aimed to establish a baseline of information on the distribution of snails in the urban environments of the Douala coastal Littoral-zone, as a first step in evaluating the status and the occurrence level of snails known as intermediate hosts of schistosomiasis and distomatosis agents. Seventy-three sample units where inspected from July to November 2020 in eight quarters of the Douala city, using 49 non-contiguous transects 5x40 m² each along streams and 24 non-contiguous quadrates 10x10 m² each around swamps. A total of 4,068 snail’s shelter belonged to 9 families: 3(33.3%) and 6 (66.7%) families for land and freshwater snails respectively. Specimens belonged to 14 genera [6 (42.9%) and 8 (57.1%) genera for land and freshwater snails respectively], and 30 species [14 (46.7%) and 16 (53.3%) species for land and freshwater snails respectively]. Land snails were most diverse [E(Sn=151) = 14 ± 0 species] than freshwater snails [E(Sn=151) = 11 ± 1 species]. Economically important species were highly represented in land snails (30.3%) and lowly represented in freshwater snails (6.1%). Between land snails Achatina and Archachatina (invasive pests for agriculture) were highly recorded in Bépanda-Sic-Cacao, Makepé-Missoké and PK10-Plateau quarters while between freshwater snails known as obligate intermediate hosts for fascioliasis and bilharzia agents, Lymnaea was recorded in Bépanda-Sic-Cacao, Nkomba and Mbanga-Pongo quarters while Biomphalaria occurred exclusively in PK10-Plateau quarter. The community exhibited low evenness, low species richness, low species diversity and low dominance by a few species. The theoretical lognormal model fitted the species abundance distributions and species exhibited a positive association (Schluter’s ratio VR = 6.69, statistic W = 53.49, df = 8, p<0.001 for land snails; VR = 2.27, W = 18.18, df = 8, p = 0.020 for freshwater snails; VR = 4.17, W = 33.42, p<0.001 for the pooled data). Low dominance by a few species indicated that study sites were slightly influenced by interspecific competition and/or disturbance by human activities.