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Macronutrients and infection in fruit flies.
Hue Dinh1, Vivian Mendez1, Shabnam Tarahi Tabrizi1
1Department of Biological Science, Macquarie University, Australia.
Insect Biochemistry and Molecular Biology
|May 15, 2019
Summary
Fruit flies alter their diet to favor carbohydrates when infected, improving survival and reducing pathogen load. This "nutritional self-medication" helps mitigate infection
Area of Science:
- Insect physiology
- Nutritional immunology
- Host-pathogen interactions
Background:
- Nutrition and infection are intricately linked in host-pathogen dynamics.
- Hosts can alter nutritional intake post-infection, but the fitness benefits are not fully understood.
- Investigating dietary modulation in insects provides insights into general principles of nutritional self-medication.
Purpose of the Study:
- To explore the relationship between dietary choices, macronutrient intake (protein and carbohydrate), infection, survival, and bacterial growth in Bactrocera tryoni.
- To determine if Bactrocera tryoni exhibits "nutritional self-medication" in response to infection.
- To assess the impact of diet composition on host survival and pathogen load.
Main Methods:
- Bactrocera tryoni were infected with Serratia marcescens or sham-infected (PBS or heat-killed bacteria).
- Dietary choices and macronutrient intake (protein:carbohydrate ratios) were monitored.
- Survival rates, pathogen load, and lipid body reserves were measured under different dietary conditions.
Main Results:
- Infected flies reduced overall food intake and shifted to a carbohydrate-biased diet (PC 1:8).
- Flies fed their selected carbohydrate-biased diet (PC 1:8) survived better than those on a protein-biased diet (PC 1:5).
- Pathogen load did not increase in infected flies fed PC 1:8 for the first 3 days; lipid reserves decreased in infected flies.
Conclusions:
- Bactrocera tryoni modulates macronutrient intake, favoring carbohydrates, to reduce infection's negative effects on survival.
- This dietary shift, termed "nutritional self-medication," appears to be an adaptive host response to infection.
- Dietary selection plays a crucial role in host defense and fitness during infection.
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