Evolving resistance to obesity in an insect

Area of Science:

• Evolutionary biology
• Nutritional science
• Insect physiology

Background:

• Modern obesity crises highlight the costs of adapting to energy-rich diets.
• Animals, including insects, face health consequences from high-energy food consumption.
• Evolutionary adaptation may allow animals to manage excess fat deposition across generations.

Purpose of the Study:

• To investigate if insects can evolve mechanisms to limit fat deposition when fed high-energy diets over multiple generations.
• To determine the fitness costs associated with excess fat storage in evolving insect populations.
• To explore how dietary changes influence insect feeding preferences and host-associated divergence.

Main Methods:

• Rearing Plutella xylostella caterpillars over multiple generations on controlled diets varying in carbohydrate content.
• Utilizing chemically defined artificial diets and a high-starch Arabidopsis mutant for high-energy conditions.
• Employing a low-starch Arabidopsis mutant for carbohydrate-scarce conditions.
• Assessing fat deposition and egg-laying preferences in evolved insect populations.

Main Results:

• Caterpillars reared on carbohydrate-rich diets evolved reduced fat deposition from excess carbohydrate intake.
• Insects from carbohydrate-scarce environments showed a higher tendency to store ingested carbohydrate as fat.
• Insects evolved host plant preferences aligned with their developmental diet, indicating potential for population divergence.

Conclusions:

• Experimental evolution demonstrates metabolic adaptation to high-carbohydrate diets in insects.
• Excess fat storage incurs a fitness cost, driving evolutionary responses.
• Shifts in plant macronutrient profiles can influence insect host association and promote population divergence.