Nadine Esther Otiobo Atibita

Background: Pollinator-dependent crops such as okra face increasing threats from intensive pesticide use, creating a need for eco-friendly pest management solutions that effectively control pests while preserving pollinator diversity and activity. Aims: Synthetic pesticides pose severe threats to non-target beneficial insects, necessitating eco-friendly alternatives for sustainable agriculture. Study Design: Ecological survey was conducted in 11 trials (four plots each). Place and Duration of Study: Investigations were carried out in Garoua (Bocklé) from June 15 to October 10, 2022. Methods: The study evaluated the comparative impact of a synthetic insecticide (TEMA) and aqueous leaf extracts from three local plants (Azadirachta indica, Eucalyptus camaldulensis and Senna occidentalis) at 5%, 10%, and 15% doses on six pollinators in okra plots across six consecutive days. Data were analysed using the negative binomial generalized linear models (GLM-NB) and the robust permutation ANOVA (5,000 iterations). Results: Out of 991 specimens, Apis mellifera adansonii acted as a keystone species, representing 53.5% of the total pollinators. TEMA triggered an immediate, devastating (90.0%) collapse in pollinators on day 49. Botanical extracts safely sheltered 85.5% pollinators. Permutation procedure unmasked significant triple interactions (P = .011). High-dose extracts (15%) exerted no repellent or toxic effect on Amegilla calens, Megachile cincta, butterflies or hoverflies, optimising and stabilising pollinator residency curves late into the cycle. Conclusion: High-dose extracts offered excellent ecotoxicological safety and non-selective bio-prevention, providing an ecologically sound alternative to conserve biodiversity in sustainable agrosystems.

Aims: Flower-visiting activity in honeybees was compared to that of Xylocopa olivacea on cowpea and sesame. Study Design: Daily activity, weekly activity, floral products and bee behavior were recorded. Place and Duration of Study: Field records (May to July 2016 and 2017) were conducted in Obala Higher Institute of Agriculture and Management campus (Bilone, Obala-Cameroon). Methodology: Thirty neighboring experimental plots (6x5.5 m each) were delimited each year (15 for sesame and cowpea respectively). Bee foragers came naturally from the station During the flowering period, in each year, day, plot and each plant species, two plants were randomly selected. Blooming flowers were checked from 1st to 14th. Daily activity was recorded each day from 6-7 a.m. to 4-5 p.m. Foragers were counted, collected floral products were identified; collection behavior and duration were recorded as well as air temperature and humidity. Results: Bee occurrences could be predicted using a linear combination of bee, plant, and air temperature. Flowers were visited from 2nd flowering day, ceased at 12th day (peak in 6th and 7th day). Daily activity started in sun shining mornings (8-9 a.m.) and stopped at 4-5 p.m., with a slight shift in activity peaks (honeybee:9-10 a.m.; Xy. olivacea: 11 a.m.-12 p.m.). Bees behaved similarly and collected nectar and pollen, with nectar collection lasting longer than pollen, which was in turn, longer in Xy. olivacea on cowpea than honeybee on sesame. Honeybees were interrupted by honeybees, Xy. olivacea and Megachile sp., and Ascalaphus africanus (Neuroptera: Ascalapidae). As for Xy. olivacea, visits were interrupted by Xy. olivacea, honeybees and As. africanus. Honeybees activity was not correlated with the climatic conditions while Xy. olivacea occurrence was positively correlated with air humidity. Conclusion: Sesame more attracted honeybees and cowpea more attracted Xy. olivacea, suggesting a probable difference in quality and/or quantity in floral products.

Aims: Investigations in cowpea fields allowed the characterization of the community structure of flower-visiting insects. Study Design: Seeds were sown in 15 plots (6x5.5 m each). Place and Duration of Study: Campus of Obala Higher Institute of Agriculture and Management (OHIAM), Bilone agroecological farm (Obala-Cameroon), from May to June 2016 and 2017. Methodology: Insects were identified in-situ or captured and stored in papillotes (Lepidoptera adults) or labelled vials containing 70° ethanol (other insects). Abundances allowed the determination of 11 alpha diversity indices. Beta diversity was tested using Bray-Curtis dissimilarity index and the correlation between species occurrences. Results: A total of 929 specimens belonged to five orders, 10 families, 13 species were recorded. Hymenoptera was the most family-rich and abundant (four families, 94.3% of the collection) followed by Diptera and Lepidoptera (two families each). Neuroptera and Orthoptera (one family each). Apidae was the most species-rich and abundant (three species; 72.9%), then Formicidae (one, 10.1%), Megachilidae (two; 9.8%). Apis mellifera (Apidae) was the most abundant (35.5%), then Xylocopa olivacea (Apidae) (22.3%), Amegilla calens (Apidae) (15.1%), Myrmicaria opaciventris (Formicidae) (10.1%), and Megachile (Chalicodoma) cincta (Megachilidae) (8.2%). The afrotropical useful predator Ascalaphus africanus (Ascalapidae) and the phytophagous pest Pteropera carnapi (Acrididae) were recorded. Exotic myasigenic species Calliphora vicina (Calliphoridae) and Musca domestica (Muscidae) were recorded. Acrididae, Nymphalidae and Pieridae cumulatively represented 3.1% pest species in the collection. Assemblages showed low species richness, high species diversity, and highly even community. Numbers of simply abundant species were close to that co-dominants. A negative correlation was noted between Acraea acerata (Nymphalidae) and Apis mellifera adansonii (Apidae), Ap. mellifera and Calliphora vicina (Calliphoridae), Ap. mellifera and Synagris conuta (Vespidae). Several positive correlations were recorded. Conclusion: In Bilone, results highlighted the importance of flower-visiting insects for the cowpea pollination and crop yield. Species were moderately abundant and assemblages functioned on the base of niche partitioning nomocenosis (log-linear model) of more or less disturbed environments with strong competition between pioneer species for the available resources.

Talinum triangulare is an herbaceous succulent plant eaten as a vegetable throughout the tropics including many countries in West and Central Africa and are an essential ingredient in traditional dishes. Experiments were made on the plant to examine the influence of foraging behavior of flowering insect on pollination and yields of this plant species in 2018 and 2019 at Bafut. Observations were made on 1615 to 4055 flowers per treatment. The treatments included unlimited floral access by visitors and bagged flowers to deny all visits. The study focused on the foraging behavior of flowering insects and their pollination activity (fruiting rate). The results show that 14 insect species visited waterleaf flowers and Camponotus flavomarginatus was the most frequent (33.20%). Insects foraged throughout the day light period. Their activity was highest between 10 am and 12 pm. Insect species foraged the flowers for pollen and nectar. The fructification rate of unrestricted floral access was significantly high than that of protected flowers to deny all visits. The maintenance of insect nest close to T. triangulare field is recommended to improve it fruits production.