Investigations were conducted to study the impact of Xylocopa olivacea on Vigna unguiculata yields and its foraging and pollinating activities were studied at Djoumassi from October 30th to November 04th in 2018 and from 04th to 10th October in 2019. Observations were made on 540 flowers divided into four treatments of which two were differentiated according to the presence or absence of flower protection regarding insect visits; the third was made of protected and opened flowers, to allow X. olivacea visits and the fourth made of opened flowers then closed without any visit. The bee’s daily rhythm of activity, their foraging and pollination activities were evaluated. Results showed that, on V. unguiculata flowers, this bee intensely and exclusively collected nectar. Through its pollination efficiency, X. olivacea has increased the podding rate by 19.44% and 27.01%, the mean number of seeds per pod by 33.42% and 29.38% and the percentage of normal seeds by 30.12% and 25.43% in 2018 and 2019 respectively. Hence, the conservation establishment and increase nests of X. olivacea close to V. unguiculata fields is recommended to improve its pod and seed yields.

Keywords: Xylocopa olivacea, Vigna unguiculata, nectar, pollination, yield, Garoua.