Resource allocation to testes in walnut flies and implications for reproductive strategy

Area of Science:

• Ecology
• Evolutionary Biology
• Insect Physiology

Background:

• Testes size is a key factor in sperm competition outcomes.
• Nutrient sources for testes development and plasticity remain underexplored.
• Holometabolous insects can utilize larval or adult diets for metabolic resources.

Purpose of the Study:

• To investigate nutrient allocation to testes development in walnut flies (Rhagoletis juglandis).
• To determine the dietary source (larval vs. adult) of carbon and nitrogen in testes.
• To understand the implications for life history evolution and reproductive strategies.

Main Methods:

• Experimental manipulation of adult diets (sugar and yeast) with distinct stable isotope ratios.
• Stable isotope analysis (carbon and nitrogen) to trace nutrient incorporation into testes over time.
• Utilizing walnut flies with known larval diets for controlled resource allocation assessment.

Main Results:

• Significant incorporation of adult dietary carbon into testes was observed.
• Walnut flies function as income breeders for carbon, relying on adult resources.
• Limited evidence for adult dietary nitrogen incorporation into testes development was found.

Conclusions:

• Nutrient allocation strategies in walnut flies differ between carbon and nitrogen.
• Adult diet significantly contributes carbon to testes, influencing reproductive investment.
• Findings contribute to understanding the evolution of male reproductive strategies shaped by nutrient availability.