Hyönteiskello

Hyönteiskello, or insect clock in English, is a simple laboratory apparatus used to study circadian rhythms in insects. It enables observation of how insect activity aligns with environmental light-dark cycles and how persistent rhythms are under constant conditions. The device is commonly used in education and introductory chronobiology research to demonstrate fundamental concepts of biological timing.

A typical insect clock consists of a clear enclosure with an insect, a programmable light source to simulate day and night, and a recording system that logs activity. Recording methods may include a moving paper drum with a pen, a photocell counter, or a digital data logger. The setup is designed to run over multiple days, allowing researchers to measure period length, phase, and the strength of rhythmic behavior while minimizing external disturbances.

Purpose and experiments often focus on entrainment to light-dark cycles, determination of the endogenous (free-running) period under constant conditions, and phase-shift responses to light pulses. Students may compare different species, assess how activity patterns change with varying cycle lengths, or study masking effects where light directly alters activity independent of the organism’s clock.

History and use: the concept arose from mid-20th century chronobiology research and became widespread in education as a hands-on tool for teaching circadian biology. While modern laboratories increasingly use digital and automated systems, traditional insect clocks remain a recognizable and inexpensive method for illustrating basic rhythmicity in insects such as cockroaches, crickets, beetles, and fruit flies.