Floral entomofaune and phénologic characteristics of Vitellaria paradoxa Gaertn.f. (Sapotaceae) in the Sudano – Guinean zone of Cameroon

Between November 2006 and June 2007 a study on floral biology of Vitellaria paradoxa was carried out in the Sudano-guinean zone of North Cameroon. Vitellaria paradoxa is a highly prized species in this zone (Mapongmetsem, 2005). Given its socio-economic importance, it is still found in a wild state and as such needs to be domesticated.

Observations were carried out in the zones of Ngaoundere and Garoua. The phenological data was taken on 45 adult trees in each zone.

It was noticed that the shading of leaves of Vitellaria paradoxa was from November to January according to individuals. This shading of leaves is more precarious in the Ngaoundéré zone than in Garoua. It’s pre-flowering last for around four weeks and is characterised by different morphogenetic phases starting from the appearance of the inflorescence bud and ending with the fall of corolla. The Vitellaria paradoxa plant are in flower from November to February in Ngaoundere and from February to June in Garoua. This occurs generally on leafless branches and presents a peak in December and March for the zones of Ngaoundere and Garoua respectively. The rate of flowering varies according to the zones. Temperature influences the flowering of Vitellaria paradoxa in the two zones. Relative humidity falls considerably irrespective of the zone during the flowering period. The anthesis in the two zones occurs between 18 hours and 23 hours. In Ngaoundéré, 54.22% against 62.48% floral buds ends the anthesis process. As concerns fruit bearing, the treatment effect is highly significant (P=0.001). In Garoua and Ngaoundéré, 2616 visits of 45 species of insects were counted on the flowers of Vitellaria paradoxa, 53.24% and 46.75% of insects visits in Ngaoundéré and Garoua respectively. Formicidae and Vespidae are the most represented families.