A scientific note on honey bee foraging activity and airborne pollen flow

Abstract

Several factors affect a honey bee colony’s collection of pollen. Most studies on this topic have focused on the colony’s response to stimuli located within the nest, principally the amount of brood and stored pollen (Hrassnigg and Crailsheim, 1998; Dreller et al., 1999; Fewell and Bertram, 1999; Rotjan et al., 2002; Vaughan and Calderone, 2002). One area that has not received adequate attention is the relationship between pollen collection and its availability in the natural environment. During the last few years, aerobiology studies demonstrated a link between airborne pollen concentration and the number of flowers in the area surrounding the sampler (Reddi and Reddi, 1985; Besselat and Cour, 1990; Cunha et al., 2003; Thibaudon and Lachasse, 2005). The aim of our work was to compare the total airborne pollen flow, collected with airborne samplers, with the total amount of pollen collected by honey bee colonies. Sampling was done in the northwest littoral of Portugal, in two rural areas, Cesar (40◦55’N, 8◦25’W, 300 m altitude) and Vairao (41◦20’N, 8◦40’W, 100 m), and one urban area, Porto (41◦11’N, 8◦39’W, 50 m). Airborne pollen flow and bee-collected pollen were studied in 2003 and 2004 at Cesar and Vairao, and in 2004 at Porto. At Cesar and Vairao, the airborne pollen content was sampled using two “Cour-type” samplers (Cour, 1974) placed at 12 m and 7 m, respectively, above ground level. The pollen was trapped in filters which were changed weekly. After acetolysis (Erdtman, 1960),