Same Host-Plant, Different Sterols: Variation in Sterol Metabolism in an Insect Herbivore Community
Sterols from pollen collected by foraging honeybees, Apis rnellifera L, at seven field sites were compared with the sterols of foraging adults andlor prepupae collected from colonies at each site. Invariably, the composition of prepupal sterols was Comparable to that found in previous cage studies using chemically defined diets containing various dietary sterols: 24-methylenecholesterol was the major sterol; sitosterol and isofucosterol were present in lesser, but significant amounts; and a trace amount of cholesterol was identified in each sample. This occurred even though some of the pollen sterols contained little 24rnethylenecholesterol, sitosterol, or isofucosterol and a preponderance of certain other sterols, such as A7-stigmasten-3&ol and A7,24(28)-campestadien-3P-ol in goldenrod and corn pollens, respectively. Thus the selective transfer and utilization of sterols in honeybees that have been demonstrated in cage studies with artificial diets were also shown to occur under field conditions.