Peer Review #2 of "Pollen extracts and constituent sugars increase growth of a trypanosomatid parasite of bumble bees (v0.1)" [peer_review]

J Lukes
2017 unpublished
Phytochemicals produced by plants, including at flowers, function in protection against plant diseases, and have a long history of use against trypanosomatid infection. Floral nectar and pollen, the sole food sources for many species of insect pollinators, contain phytochemicals that have been shown to reduce trypanosomatid infection in bumble and honey bees when fed as isolated compounds. Nectar and pollen, however, consist of phytochemical mixtures, which can have greater antimicrobial
more » ... ntimicrobial activity than do single compounds. This study tested the hypothesis that pollen extracts would inhibit parasite growth.Extracts of six different pollens were tested for direct inhibitory activity against cell cultures of the bumble bee trypanosomatid gut parasite Crithidia bombi. Surprisingly, pollen extracts increased parasite growth rather than inhibiting it. Pollen extracts contained high concentrations of sugars, mainly the monosaccharides glucose and fructose. Experimental manipulations of growth media showed that supplemental monosaccharides (glucose and fructose) increased maximum cell density, while a common floral phytochemical (caffeic acid) with inhibitory activity against other trypanosomatids had only weak inhibitory effects onCrithidia bombi. These results indicate that, although pollen is essential for bees and other pollinators, pollen may promote growth of intestinal parasites that are uninhibited by pollen phytochemicals and, as a result, can benefit from the nutrients that pollen provides. PeerJ reviewing PDF | Abstract 16 Phytochemicals produced by plants, including at flowers, function in protection against plant 17 diseases, and have a long history of use against trypanosomatid infection. Floral nectar and 18 pollen, the sole food sources for many species of insect pollinators, contain phytochemicals that 19 have been shown to reduce trypanosomatid infection in bumble and honey bees when fed as 20 isolated compounds. Nectar and pollen, however, consist of phytochemical mixtures, which can 21 have greater antimicrobial activity than do single compounds. This study tested the hypothesis 22 that pollen extracts would inhibit parasite growth. Extracts of six different pollens were tested 23 for direct inhibitory activity against cell cultures of the bumble bee trypanosomatid gut parasite 24 Crithidia bombi. 25 Surprisingly, pollen extracts increased parasite growth rather than inhibiting it. Pollen extracts 26 contained high concentrations of sugars, mainly the monosaccharides glucose and fructose. 27 Experimental manipulations of growth media showed that supplemental monosaccharides 28 (glucose and fructose) increased maximum cell density, while a common floral phytochemical 29 (caffeic acid) with inhibitory activity against other trypanosomatids had only weak inhibitory 30 effects on Crithidia bombi. These results indicate that, although pollen is essential for bees and 31 other pollinators, pollen may promote growth of intestinal parasites that are uninhibited by pollen 32 phytochemicals and, as a result, can benefit from the nutrients that pollen provides. 33 PeerJ reviewing PDF |
doi:10.7287/peerj.3297v0.1/reviews/2 fatcat:eeadnxt66beargqifax54qrcse