Foraging and pollination behaviour of Chalicodoma rufipes L. (Hymenoptera: Megachilidae) on Cajanus cajan L. Mill sp. (Fabaceae) flowers at Dang (Ngaoundéré, Cameroon)

Abstract To evaluate Chalicodoma rufipes impact on fruit and seed yields of Cajanus cajan L., its foraging and pollinating activities were studied in Ngaoundéré for two seasons. Observations were made on 340 flowers each year and divided in three treatments. The treatments included unlimited flowers access by all visitors; bagged flowers to deny all visits and limited visits by Ch. rufipes only. Chalicodoma rufipes worker seasonal rhythm of activity, their foraging behaviour, their pollination efficiency, the fruiting rate, the number of seeds per pod and the percentage of normal seeds were evaluated. Results show that Ch. rufipes foraged Ca. cajan flowers throughout the whole blooming period. That bee intensely harvested pollen and nectar. The mean foraging speed was 11.50 flowers per minute in 2010 and 12.45 flowers per minute in 2011. The fruiting rate, the number of seeds per fruit and the percentage of normal seeds of unprotected flowers were significantly higher than those of flowers protected from insects. Through their pollination efficiency, that bee provoked a significant increment of the fruiting rate by 95.38% in 2010 and 96.72% in 2011, as well as the mean number of seeds per fruit by 04.28 in 2010 and 04.93 in 2011, and the percentage of normal (well developed) seeds by 50.72% in 2010 and 61.79% in 2011. The installation of Ch. rufipes nests close to Ca. cajan fields could be recommended to increase fruit and seed yields and to alleviate poverty in that region.