Punch in the gut: Parasite tolerance of phytochemicals reflects host diet

Authors: PALMER-YOUNG, EVAN - Orise Fellow; SCHWARZ, RYAN - Fort Lewis College; Chen, Yanping - Judy; Evans, Jay

Submitted to: Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2022
Publication Date: 3/22/2022
Citation: Palmer-Young, E., Schwarz, R., Chen, Y., Evans, J.D. 2022. Punch in the gut: Parasite tolerance of phytochemicals reflects host diet. Environmental Microbiology. 24(4):1805-1817. https://doi.org/10.1111/1462-2920.15981.
DOI: https://doi.org/10.1111/1462-2920.15981

Interpretive Summary: Trypanosome parasites of honey bees have been linked with poor winter survival. There are no registered treatments for these parasites. Here we test 25 compounds for activity against two bee parasites. We identify several that show promise as novel antibiotics. The results can be used in planning floral resources for honey bees and other pollinators and for the development of novel disease treatments aimed at stabilizing pollinator populations.

Technical Abstract: Gut parasites of plant-eating insects are exposed to antimicrobial phytochemicals that can reduce infection. Trypanosomatid gut parasites infect insects of diverse nutritional ecologies as well as mammals and plants, raising the question of how host diet-associated phytochemicals shape parasite evolution and host specificity. To test the hypothesis that phytochemical tolerance of trypanosomatids reflects the chemical ecology of their hosts, we compared related parasites from honey bees and mosquitoes—hosts that differ in phytochemical consumption—and contrasted our results with previous studies on phylogenetically related, human-parasitic Leishmania. We identified one bacterial and ten plant-derived substances with known antileishmanial activity that also inhibited honey bee parasites associated with colony collapse. Bee parasites exhibited greater tolerance of chrysin—a flavonoid found in nectar, pollen, and plant resin-derived propolis. In contrast, mosquito parasites were more tolerant of cinnamic acid—a product of lignin decomposition present in woody debris-rich larval habitats. Parasites from both hosts tolerated many compounds that inhibit Leishmania, hinting at possible trade-offs between phytochemical tolerance and mammalian infection. Our results implicate the phytochemistry of host diets as a potential driver of insect-trypanosomatid associations, and identify compounds that could be incorporated into colony diets or floral landscapes to ameliorate infection in bees.