Circadian Rhythm of Activity and Foraging Behavior in Two Flower-Visiting Bee Species on Sesame and Cowpea Plants in Bilone,Obala,Cameroon

Abstract

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.