Study of the food-searching activity by smell in diving beetles of Cybister Curtis, 1827 and Hydaticus Leach, 1817 (Coleoptera: Dytiscidae) including the use of a microwave Doppler radar

Abstract

To investigate how four species of Cybister Curtis, 1827 and one species of Hydaticus Leach, 1817 (Coleoptera: Dytiscidae) detect food, insects were provided with dried sardines using traps made by a three-dimensional printer. More than 83% of the beetles found the sardine hidden in the trap. When the two traps were set in an aquarium—one contained a dried sardine before extraction with boiled water, and another contained a dried sardine after extraction—more than 90% of beetles were caught in the trap with the sardine before extraction. In contrast, less than 3% of beetles entered the trap with the sardine after extraction. No feeding preference was found between the sardines before and after extraction. A microwave Doppler radar was used to quantitatively detect the behaviour using broth extracted from the sardines, and the broth enhanced the food-searching activity. These results suggest that these beetles use smell to find food, and their searching activities are induced by smell.

Keywords:

• Attractiveness of food
• detection of food
• food-searching behaviour
• microwave Doppler radar
• three-dimensional printed trap

Acknowledgements

The article will be dedicated to my (T. Inoda) beloved dog, Miku, she passed away (July 14, 2022) at nine years old. She has always watched me conduct this research. The authors thank Y. Miyazaki for help with insect (Cybister rugosus) collection.

Disclosure statement

No potential conflict of interest was reported by the authors.