Assessment of origin and relative contributions of various plant species as honeybee (a. Mellifera) pollen sources

Abstract

Survival of honeybee colony is totally linked to its ability to collect sufficient quantities of pollen and nectar from plants flower. This study analyzes the origin and relative contributions of various floral sources around Utrecht University, Netherlands through pollen collection from honeybees (A.mellifera L.) during seven months of 2003. The study identified 50 different plant families comprising 105 different species in the whole collections with an average of 10.3 species per collection week. There was a significant variations (2 =6519.622, df=26, p<0.01) in the amount of pollen collected between the weeks with an average of 140.6g. Only 13 families contributed to more than 95% of the collection in which the four most important contributors Rosaceae (39.59%), Legumes (18.28%), Oleaceae (11.97%) and Compositae (8.08%)) accounted for more than 77%. Shannon Weiner index indicated low pollen source species diversity in the first weeks and at climax in the middle with subsequent declining as season advanced. Four different plant life forms (shrubs, herbs, trees and grasses) were identified in the total collections and shrubs and herbs alone contributed for 95% of the total pollen collections. Similarly, Pearson product-moment correlation coefficient showed a strong negative correlation (r= -532, n=27, P<0.05) between the amount of pollen and number of species collected, suggesting bee’s pollen collection behavior is largely influenced by pollen availability than the species diversity.