Analysis of pollen and nectar of Arbutus unedo as a food source for Bombus terrestris (Hymenoptera: Apidae).
The mineral, total amino acid, and sterol compositions of pollen collected by Apis mellifera L. were compared with the pollen of a plant consumed by Bombus terrestris (L.): Arbutus unedo L. This plant provides the predominant food resource for the main autumn generation of B. terrestris in southern France. Honey bees also forage on this plant, although only for nectar. The mineral composition of 30 pollen samples collected by honey bees is close to the presently known requirements of A. mellifera, except for Cu and Mn, which are substantially lower. The total amino acid mean composition of a set of 54 pollen samples fits the basic requirements of honey bees except for valine, isoleucine, and methionine, which are present in lower concentrations in all the samples. For pollen of A. unedo, the amino acid balance is not very different from that of the survey. The main sterolic component in pollen of A. unedo, beta-sitosterol, is known to have antifeedant effects on A. mellifera. Honey bees cannot dealkylate C29 sterols like beta-sitosterol or delta5-avenasterol to obtain C27 cholesterol and ecdysteroids. Because these phytosterols as well as cholesterol are nearly absent from pollen of A. unedo, the metabolic capabilities of Apis seem unadapted to this plant. On the contrary, pollen of A. unedo is freely consumed by B. terrestris, which develops huge autumn populations solely on this food. These data indicate that the sterolic metabolisms of B. terrestris and A. mellifera differ, allowing separation in foraging activity.
Rasmont
Pierre
P
Université de Mons-Hainaut, B-7000 Mons, Belgium. pierre.rasmont@umh.ac.be
Regali
Ariane
A
Ings
Thomas C
TC
Lognay
Georges
G
Baudart
Evelyne
E
Marlier
Michel
M
Delcarte
Emile
E
Viville
Pascal
P
Marot
Cécile
C
Falmagne
Pol
P
Verhaeghe
Jean-Claude
JC
Chittka
Lars
L
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001516:Bees / Q000502:physiology*; D004032:Diet; D029791:Ericaceae / Q000737:chemistry*; D008903:Minerals / Q000032:analysis; D011058:Pollen / Q000737:chemistry*; D013261:Sterols / Q000032:analysis
D000596:Amino Acids; D008903:Minerals; D013261:Sterols