Analysis of Pollen and Nectar of <I>Arbutus unedo</I> as a Food Source for <I>Bombus terrestris</I> (Hymenoptera: Apidae)

Abstract

Abstract: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, β-sitosterol, is known to have antifeedant effects on A. mellifera. Honey bees cannot dealkylate C 29 sterols like β-sitosterol or 85-avenasterol to obtain C 27 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.

Pollen and nectar quality drive the major and minor floral choices of bumble bees

“…The 24-methylenecholestrol has been reported to be among the most important phytosterol for bees (Human et al 2007;Svoboda et al 1980). β-sitosterol and δ5-avenasterol have been reported to have a phagostimulant effect on bumble bee species (Rasmont et al 2005). Cirsium palustre contained a high relative proportion of δ7-stigmasterol, which is a common sterol to several Asteraceae (Janson et al 2009).…”

“…Phytosterols are further requisite nutrients since they are precursors of molting hormones, and bees are not able to synthesize them de novo (Behmer and Nes 2003;Cohen 2004). All these essential nutrients are highly variable among plant species (Rasmont et al 2005;Vanderplanck et al 2014a).…”

Specialized Bees Fail to Develop on Non-Host Pollen: Do Plants Chemically Protect Their Pollen

“…Lack of essential sterols in the pollen was postulated to account for the observation that honey bees did not forage on Arbutus unedo (Ericaceae) for pollen, although they collected nectar from it (Rasmont et al 2005). Similarly, pure pollen diets of Taraxacum officinale (Asteraceae) proved to be inadequate for both honey bee adults and larvae (reviewed in .…”

“…Pollen of Asteraceae was shown to be of poor quality for the honey bee (Herbert et al 1970, Rayner and Langridge 1985, Somerville and Nicol 2006, for bumblebees (Rasmont et al 2005) as well as for two polylectic solitary bee species (Levin andHaydak 1957, Guirguis andBrindley 1974). Of 153 polylectic bee species observed visiting native sunflowers (Helianthus), the great majority (86%) were casual visitors exploiting sunflowers in small numbers (Hurd et al 1980).…”

Effects of Three Kinds of Sugar Syrups on Colony Development of Bumble Bee (Bombus terrestris L.)

“…In extensive commercial rearing, bumble bee colonies are normally fed on sucrose or invert sugar solutions (as substitutes for nectar) and fresh pollen collected from pollen traps at honey bee hives. This diet seems to provide adequate nutrition for good colony development (Plowright and Jay, 1966;Ribeiro et al, 1996;Rasmont et al, 2005).…”