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EFFECTS OF FLORAL PHYTOCHEMICALS ON GROWTH AND EVOLUTION OF A PARASITE OF BUMBLE BEES
Background: Nectar and pollen are rich in phytochemicals, some of which can reduce disease in pollinators, including agriculturally important honey and bumble bees. Floral phytochemicals could influence the ecological and evolutionary relationships between plants, their pollinators, and parasites that cause pollinator disease. Antiparasitic effects of phytochemicals could be exploited to ameliorate pollinator disease and decline, and thereby sustain pollinator-dependent agricultural production. However, prior studies showed variable effects of phytochemicals on infection in live bees, where differences in bee genotype, abiotic conditions, and parasite strain could influence results.
Approach: I used cell cultures of the intestinal trypanosome parasite of bumble bees, Crithidia bombi, to (1) describe how resistance to 9 floral phytochemicals varied among 4 parasite strains, (2) describe the antiparasitic effect of phytochemical combinations, and (3) test for evolution of resistance to individual phytochemicals and a two-phytochemical blend.
Results:
(1) Resistance to floral phytochemicals: C. bombi showed striking resistance to the phenolics gallic acid, caffeic acid, and chlorogenic acid at levels beyond those found in nectar and pollen; literature searches showed that C. bombi resistance to these compounds exceeded that of bloodstream trypanosomes by several orders of magnitude. Phytochemical resistance varied among C. bombi isolates, indicating that medicinal effects of phytochemicals are dependent on parasite strain. Thymol and eugenol inhibited growth at concentrations below the toxicity thresholds of bees. Inhibitory concentrations of thymol were similar to those found in Thymus vulgaris nectar, indicating that medicinal effects of phytochemicals on pollinator disease are ecologically relevant, and could be achieved through strategic planting of phytochemical-rich flowers.
(2) Synergistic effects of combined phytochemicals: Thymol and eugenol had synergistic effects against 3 of 4 C. bombi strains—inhibition of parasites exposed to phytochemical combinations was stronger than predicted based on the activities of isolated phytochemicals. Synergy between phytochemicals suggests that phytochemical combinations may have greater antiparasitic potential in comparison to single phytochemicals. Synergistic phytochemical combinations in diverse floral landscapes could allow pollinators to self-medicate without toxicity, thereby ameliorating diseases that contribute to pollinator decline.
(3) Evolution of resistance to phytochemicals: Resistance of C. bombi increased under single and combined phytochemical exposure, without any associated cost of reduced growth under phytochemical-free conditions. After six weeks’ exposure, phytochemical concentrations that initially inhibited growth by \u3e50%, and exceeded concentrations in floral nectar, had minimal effects on evolved parasite lines. Unexpectedly, a two-phytochemical combination did not impede resistance evolution compared to single compounds. These results demonstrate that repeated phytochemical exposure, which could occur in homogeneous floral landscapes or with therapeutic phytochemical treatment of managed hives, can cause rapid evolution of resistance in a pollinator parasite. Evolved resistance could diminish the antiparasitic value of phytochemical ingestion, weakening an important natural defense against infection.
Conclusion: These results show the potential of phytochemical-rich flowers to directly ameliorate pollinator infection, a recognized contributor to bee decline. Results also suggest benefits of diverse landscapes for pollinator health. Phytochemically complex mixtures in diverse floral landscapes could synergistically inhibit parasite growth and curtail the evolution of phytochemical resistance in parasites, thereby optimizing the medicinal effects of phytochemicals on bees. Deliberate planting of high-phytochemical crops and hedgerow species could reduce the effects of disease on bee populations, thereby benefitting agricultural production
Human reproduction in space. Late results
Objectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version
Satellite power system: Concept development and evaluation program, reference system report
The Satellite Power System (SPS) Reference System is discussed and the technical and operational information required in support of environmental, socioeconomic, and comparative assessment studies are emphasized. The reference System concept features a gallium-aluminum-arsenide, and silicon solar cell options. Other aspects of an SPS are the construction of bases in space, launch and mission control bases on earth, and fleets of various transportation vehicles to support the construction and maintenance operations of the satellites
ACS Without an Attitude
The book (ACS without an Attitude) is an introduction to spacecraft attitude control systems. It is based on a series of lectures that Dr. Hallock presented in the early 2000s to members of the GSFC flight software branch, the target audience being flight software engineers (developers and testers), fairly new to the field that desire an introductory understanding of spacecraft attitude determination and control
HSCI2012: proceedings of the 9th International Conference on Hands-on Science
Including 1st Childrens’ Summit on Hands-on Science & Environmental Education. The core topic of the 9th Hands-on Science Conference are “Science Education,
Environment and Society" and "Reconnecting Society with Nature through Hands-on
Science”.Livro que reúne os trabalho extensos aceites para publicação nos proceedings da 9th HSCI conferenc
Saving Bones: a direct comparison of FTIR-ATR, whole bone percent nitrogen, and NIR
89th Annual Meeting of the American-Association-of-Physical-Anthropologists (AAPA), Los Angeles, CA, APR 15-18, 202
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