Pollination Efficiency of <i>Ceratina cyanea</i> (Hymenoptera: Apidae) on <i>Helianthus annuus</i> (Asteraceae) Flowers at Dang (Ngaoundere, Cameroon)

Abstract

To evaluate the impact of Ceratina cyanea on fruit and seed yields of sunflower, experimental field was set up from June to July in 2016 and 2017 at Dang. Observations were done on 540 capitula divided in four treatments: two treatments differentiated according to the presence or absence of protection on capitula regarding Ceratina cyanea and other flowering insects’ visits; the third with capitula protected and uncovered when florets were opened, to allow C. cyanea visits and flowers bagged uncovered and rebagged without the visit of insects or any other organisms. Bee’s daily rhythm of activity, its foraging behavior on florets and its pollination efficiency were evaluated. Bee’s daily rhythm of activity, its foraging behavior on flowers and its pollination efficiency were evaluated. Results show that, C. cyanea foraged on Helianthus annuus flowers throughout its whole blooming period. Among 32 insect species recorded on H. annuus capitula, C. cyanea ranked second accounting for 10.79% all visits, after Apis mellifera (76.06%). On florets, individual bees intensely harvested nectar and slightly collected pollen. The mean duration of a visit per floret was 3.62 sec for nectar harvest and 9.58 sec for pollen collection. For the two years, through its pollination efficiency on H. annuus , C. cyanea has increased the fruiting rate by 65.90%, the percentage of fruit with seed by 63.56% and the percentage of normal seeds by 76.11%. Based on these results, we recommend the protection of C. cyanea nests at the vicinity of sunflower fields to increase its fruit and seed yields in the Adamaoua Region of Cameroon.