Synergistic effects of floral phytochemicals against a bumble bee parasite

Abstract

Floral landscapes comprise diverse phytochemical combinations. Individual phytochemicals in floral nectar and pollen can reduce infection in bees and directly inhibit trypanosome parasites. However, gut parasites of generalist pollinators, which consume nectar and pollen from many plant species, are exposed to phytochemical combinations. Interactions between phytochemicals could augment or decrease effects of single compounds on parasites. Using a matrix of 36 phytochemical treatment combinations, we assessed the combined effects of two floral phytochemicals, eugenol and thymol, against four strains of the bumblebee gut trypanosome Crithidia bombi. Eugenol and thymol had synergistic effects against C. bombi growth across seven independent experiments, showing that the phytochemical combination can disproportionately inhibit parasites. The strength of synergistic effects varied across strains and experiments. Thus, the antiparasitic effects of individual compounds will depend on both the presence of other phytochemicals and parasite strain identity. The presence of synergistic phytochemical combinations could augment the antiparasitic activity of individual compounds for pollinators in diverse floral landscapes.

Evaluation of in-vitro antibacterial and antifungal activities of crude extracts and solvent fractions of methanol extract of leaves of Ricinus communis Linn (Euphorbiaceae) against selected pathogens

“…Hexane and chloroform fractions revealed the lowest antibacterial activity and no antifungal activity. This could be due to variations in the concentration of secondary metabolites present in the solvent fractions [35,36]. Ethyl acetate fraction revealed highest antibacterial activity than crude extracts and solvent fractions which is in agreement with the nding of the previous study done by Voukeng et al [19].…”

“…The aqueous fraction exhibited the highest antifungal activity followed by ethyl acetate fraction perhaps due to the capability of ethyl acetate solvent in concentrating a greater number of secondary metabolites from partitioning of methanol crude extract and interaction of these phytochemical constituents. Secondary metabolites with antifungal activity are concentrated more in aqueous solvent of methanol crude extract [35,36,37].…”

pH-mediated inhibition of a bumble bee parasite by an intestinal symbiont

“…Strains S08.1 (Switzerland, 2008, courtesy Ben Sadd) originated from B. terrestris. These same cell lines have been used to assess effects of phytochemicals on parasite growth (78). Briefly, cells from fecal samples were sorted into 96-well plates containing “FPFB” culture medium with 10% heat-inactivated fetal bovine serum and incubated at 27 °C.…”

A Review of Native Wild Bee Nutritional Health

“…Secondary plant compounds may also have positive effects on a bee post ingestion. The nectar alkaloid anabasine was found to strongly decrease Crithidia bombi Leger parasite loads when its bumble bee host, B. impatiens, was fed high concentrations [61][62][63]. Bees may be self-medicating with secondary compounds in nectar.…”