Abstract

Plant colour contrast as perceived by insect pollinators is important in our understanding of pollination ecology, foraging theory and conservation of plant species. Field experiment was conducted on the interactions between honeybee Apis mellifera L. and flower colour contrast of sunflower as influenced by different levels of NPK 15-15-15 fertilizer application at Forestry Research Institute of Nigeria, Jericho-Hills Ibadan. Two sunflower varieties combined with four levels of NPK-15-15-15 fertilizer were laid out in Randomized Complete Block Design with three replicates and data were collected on honeybee abundance, sunflower ray florets colour contrast, vitamin A and β-carotenoid contents of the ray florets, crude protein, fats and flavonoid contents of pollen grain and foraging response of honeybees to the treatment. The degree of association between honeybee length of visit and ray florets colour contrast was also investigated. Analysis of Variance, SNK test, and Pearson’s correlation (α=0.05) were used for data analysis. Results indicated that NPK-15-15-15 fertilizer significantly (p>0.05) increased pollen grain crude protein, fat, flavonoid contents, vitamin A and β-carotenoid contents of the flowers florets of the sunflower varieties used in the study at 90 kgha^-1. Honeybees  also demonstrated distinct foraging preference for both sunflower varieties at 90 kgha^-1 NPK 15-15-15 (p<0.05) corresponding to golden yellow in Jos Local and titanium lemon yellow in SAM-SUX-1 variety, relative to other yellow colour tints.

Key Words:Honeybee, Interactions, Flower colour, Sunflower, NPK fertilizer