Energetic constraints on multi-day flights in migratory locusts

Area of Science:

• Animal Migration
• Insect Energetics
• Ecological Physiology

Background:

• Animal migration requires substantial energy, often met by lipid stores.
• Locust swarms cause significant agricultural damage, but their migration energetics are poorly understood.

Purpose of the Study:

• To investigate the nutritional and energetic demands of locust migration.
• To determine if locusts can maintain energy stores during sustained flight with optimal feeding.

Main Methods:

• Measured flight duration, fuel stores, and macronutrient intake in migratory locusts (Locusta migratoria) during three days of tethered flight.
• Compared flying locusts with a non-flying control group.
• Developed two models to analyze lipid loss and refueling capacity during migration.

Main Results:

• Locusts increased carbohydrate intake by ~30% during flight days but lost ~30% of stored body lipid despite 19 hours/day access to food.
• Modeling suggests locusts cannot sustain more than ~1 hour of daily flight without energy deficits.
• Flight capacity is limited by intake and assimilation, highlighting the need for substantial pre-migratory lipid reserves.

Conclusions:

• Long-distance locust migration is energetically demanding and requires significant pre-migratory lipid accumulation.
• Extended stopovers for feeding are crucial for locusts to replenish energy stores during migration.
• Understanding locust energetics is key to predicting migration dynamics and impacts.