Effects of Apis mellifera adansonii, L. 1758 (Apidae: Hymenoptera) pollination on yields of Cucumeropsis mannii (Naudin) in Kisangani, Democratic Republic of Congo
The honeybees play an important role in the pollinations of many field crops. Here, we assessed the effect of the presence of honeybee colonies, A. mellifera adansonii, L. 1758 (Apidae: Hymenoptera) in the production of African melon crop, C. mannii (Naudin) (Cucurbitaceae) in Kisangani, Democratic Republic of Congo. The influences of distance to the apiary and flight orientation were also investigated. Generally, four fields of one hectare were cultivated in two study sites. At each site, both fields of one hectare were separated by more than 3 kilometers to avoid interference between treatments. Two honeybee colonies were installed in the middle of the first experimental field at each site (T1) during flowering (when there were 10% of flowering plants). A second experimental field, without honeybee colonies, was the control (T0). Each experimental field (with or without colonies) was divided into three concentric subplots around the apiary (P1: 0-10 meters to the apiary, P2: 10-30 meters, and P3: 30-50 meters to the apiary). The impact of pollination of honeybees on the yield of C. mannii was assessed on five components of yield (average number of seeds per fruit, average number of fruits per plant, average weight of seeds extracted per fruit, average length and average width of the seeds). The results of this study have shown that the pollination of introduced honeybees significantly improved the number of seeds per fruit by 83.78%, while the number of fruits per plant and the weight of seeds per fruit were improved by 422.89% and 185.61%, respectively. Indeed, the seed size was positively influenced by the presence of the apiary in the field. According to the findings in this study, the spatial distribution of plants (distance to apiary and orientation) did not influence the yield and the size of seeds in the field of C. mannii. The association "apiary - culture of C. mannii" could be integrated in the arsenal of strategies to enhance symbiotic interactions Apis mellifera with C. mannii in DRC.
Keywords: Apis mellifera adansonnii, L., pollination, Cucumeropsis mannii (Naudin), yield, Kisangani, RDC.