Diversity of Flowering Insects and Their Impact on Yields of Phaseolus Vulgaris L. (Fabaceae) in Yaoundé (Cameroon)

To evaluate the diversity and impact of insect pollinators on pod and seed yields of Phaseolus vulgaris (red bean with small seeds), its foraging and pollinating behavior were studied in Yaoundé, during the mild raining season (March-June) in 2016 and 2017. Treatments included unlimited floral access by all visitors and bagged flowers to avoid all insect pollinators. For each year of study, observations were made on 55 ± 38 flowers per treatment. The seasonal rhythm of insects activities, its foraging behavior, and its impact on pollination (fruiting rate, number of seeds/pod and percentage of normal seeds) were recorded. Fourteen insect species visited P. vulgaris flowers. Out of 667 visits, Xylocopa olivacea, Halictus sp., Chalicodoma sp. and Apis mellifera adansonii were the most frequent visitors with 21.43 %, 19.49 %, 12.44 % and 10.04 % visits respectively. These insects collected nectar and pollen intensely and regulatedly. The foraging activities of insect pollinators increased the fruiting rate by 23.56 %, the number of seeds/pod by 46.31 % and the normal seeds by 21.49 %. Therefore, conservation of nests and colonies of insect pollinators close to P. vulgaris crop fields should be recommended to improve pod and seed production in the region.