Foraging and pollination behavior of Apis mellifera adansonii Latreille (Hymenoptera, Apidae) on Brachiari brizantha (Hochst. Ex A. Rich.) Stapf. 1919 flowers at Dang (Ngaoundere- Cameroon)

To evaluate the Apis mellifera adansonii Latreille (Hymenoptera: Apidae) impact on fruit and seed yields of Brachiaria brizantha H. (1919) (Poaceae), A. m. adansonii workers foraging and pollinating activities were studied in Ngaoundéré. From September to October 2010 and from September to October 2011, the experiments were carried out on 240 and 440 inflorescences divided in three lots: two lots differentiated according to the presence or absence of protection regarding A. m. adansonii and other insects visits; the third protected and uncovered when flowers were open, to allow insect visits. Worker’s seasonal rhythm of activity, its foraging behavior on flowers, its pollination efficiency, the fructification rate and the percentage of normal seeds were evaluated. Results show that A. m. adansonii foraged on B. Brizantha flowers throughout the whole blooming period. This bee intensely and preferably harvested pollen. The greatest mean number of individuals foraging simultaneously on 1000 flowers was 10 in 2010 and 625 in 2011. The mean duration of a visit per spikelet was 5.77  5.08 sec in 2010 and 4.94  3.44 sec in 2011. The mean foraging speed was 4.55 flowers/min in 2010 and 6.86 flowers/min in 2011. The fructification rate and the percentage of normal seeds of unprotected inflorescences were significantly higher than those of inflorescences protected from insects. Through its pollination efficiency, A. m. adansonii provoked a significant increment of the fructification rate by 37.70 % in 2010 and 34.75 % in 2011, as well as the percentage of normal seeds by 3.39 % in 2010 and 6.82 % % in 2011. The installation or conservation of A. m. adansonii nests close to B. brizantha fields could be recommended to increase seeds and fruits production in the region.