Abstract
Background:
Understanding honey bee pollen foraging behavior is crucial for optimizing pollination services in agricultural systems. Floral characteristics and pollen traits significantly influence pollinator preferences and foraging efficiency.

Aim:
This study investigated how floral characteristics and pollen traits influence the foraging preferences of honey bee (Apis mellifera ligustica) in Australian cotton agroecosystems.

Methods:
Pollen traps were installed on eight honey bee colonies adjacent to cotton fields during summer 2007. Collected pollen pellets were analyzed for weight, color, and botanical origin. Scanning electron microscopy (SEM) was used to examine pollen morphology and size. Statistical analyses included Pearson's correlation and ANOVA with Tukey's HSD test.

Results:
Honey bees showed significant preferences for specific pollen sources (F₇,₂₈ = 84.593, p < 0.02). Acacia concurrens was the most collected species (37.4%), followed by Maireana villosa (17.5%) and Helianthus annuus (13.3%). Cotton (Gossypium hirsutum) contributed only 5.3% of total pollen. A strong negative correlation was found between pollen grain size and pellet weight (r = -0.89, p < 0.05). Smaller, smooth-textured grains (e.g., M. villosa, 31 μm) yielded heavier pellets (6.42 mg), while larger grains (e.g., G. hirsutum, 101 μm) produced lighter pellets (2.45 mg). Brightly colored flowers (yellow and orange) were strongly preferred over creamy-white blossoms.

Conclusion:
Honey bees optimize foraging by selecting flowers with favorable morphology, vibrant colors, and collectible pollen traits. The low preference for cotton pollen despite its abundance highlights the importance of alternative floral resources for maintaining honey bee colonies in agricultural landscapes.

Key words: Apis mellifera; Foraging ecology; Pollen morphology; Scanning electron microscopy; Australia.