Metabolic cost of flight and aerobic efficiency in the rose chafer, Protaetia cuprea (Cetoniinae)

Abstract

Rose chafer beetles (Protetia cuprea) are pollinators as well as agricultural pests, flying between flowers and trees while foraging for pollen and fruits. Calculating the energy they expend on flying during foraging activity faces the challenge of measuring the metabolic rate (MR) of free‐flying insects in an open space. We overcame this challenge by using the bolus injection of 13C Na‐bicarbonate technique to measure their metabolic energy expenditure while flying in a large flight arena. Concurrently, we tracked the insects with high‐speed cameras to extract their flight trajectory, from which we calculated the mechanical power invested in flying for each flight bout. We found that the chemical (metabolic) energy input converted to mechanical flight energy output at a mean efficiency of 10.4% ± 5.2%, with a trend of increased efficiency in larger conspecifics (efficiency scaled with body mass to the power of 1.4). The transition in the summer from a diet of pollen to that of fruits may affect the energy budget available for foraging. Starved P. cuprea, feeding on apples ad libitum, increased their body mass by an average of 6% in 2 h. According to our calculations, such a meal can power a 630‐m flight (assuming a carbohydrate assimilation efficiency of 90%). Pollen, with a low water and carbohydrate content but rich in proteins and lipids, has a higher caloric content and should assimilate differently when converting food to flight fuel. The high cost of aerial locomotion is inherent to the foraging behavior of rose chafers, explaining their short flight bouts followed by prolonged feeding activity.

Tailoring the Mechanical Properties of High‐Fidelity, Beetle‐Inspired, 3D‐Printed Wings Improves Their Aerodynamic Performance

“…It can hover, fly forward at high speed, perform sharp maneuvers, and land stably on small perches. [37,38] Like many beetles, it flies with a high wing loading compared to other insects with similar wing size. [39] The capabilities of its flight apparatus are therefore highly attractive for the development of miniature (centimeter-scale) drones that are required to function with a relatively high payload due to the electronic components they carry.…”

Intraspecific scaling and early life history determine the cost of free‐flight in a large beetle (Batocera rufomaculata)

“…However, to truly represent the energetic cost of flight, flight MR should be measured in flying insects that are free to reach desired flight speeds and perform aerial maneuvers while supporting their full body weight in air (Ellington, 1984b;Dudley & Ellington, 1990;Snelling et al, 2012;Ribak et al, 2017;. The "bolus injection of isotopic 13 C Na-bicarbonate" method was recently shown to enable such measurements in free-flying beetles Urca et al, 2022). Here, we applied the technique on B. rufomaculata (Fig.…”