Insect Clocks

Preface


1. Introduction: Rhythms and Clocks


2. Circadian Rhythms of Activity in Individual Insects

A. Activity Rhythms in Light/Dark-cycles

B. The Endogenous Nature of Activity Rhythms

1. "Free-running" Behavior in the Absence of Temporal Cues

2. "Aschoff's Rule" and the "Circadian Rule"

3. Temperature-compensation of the Circadian Period

4. Bimodal Activity Patterns

C. Exogenous Effects

D. Entrainment by Light and Temperature

1. Entrainment by Light-cycles

2. Phase-shifting by Light-cycles and Pulses, and the Phase-response Curve

3. Entrainment by Temperature Cycles and Pulses


3. Circadian Rhythms of Activity in Populations of Insects

A. General Properties of the Pupal Eclosion and Other Rhythms

B. Population Rhythms as "Gating" Phenomena

C. Entrainment of Population Rhythms by Light and Temperature

1. The Phase Response Curve

2. Entrainment by Single Recurrent Light Pulses of Short Duration

3. Entrainment by "Skeleton" Photo-periods

4. Entrainment by Temperature Pulses and Cycles

D. Genetic Experiments

E. "Stopping" the Clock

1. Low Oxygen Tension and Cold Torpor

2. The Damping Action of Photo-periods in Excess of about 12 Hours

3. The "Singularity Point"

F. Spectral Sensitivity and Intensity Effects


4. Circadian Rhythms and Physiology: The Circadian System

A. Rhythms of Cuticle Deposition

B. Metabolic Rhythms

C. Rhythms in the Endocrine and Central Nervous Systems

D. Sensitivity to Drugs and Insecticides

E. Environmental Periodicity and Fundamental Aspects of Physiology

F. Temporal Organization and the Circadian System


5. Photo-periodism and Seasonal cycles of Development

A. Dormancy: Quiescence and Diapause

B. Seasonal Morphs

C. Growth Rates

D. Migration

E. Miscellaneous Photo-periodic Phenomena


6. The Photo-periodic Response

A. Types of Response

B. The Sensitive and Responsive Stages

C. Maternal Induction of Diapause and Seasonal Forms

D. Factors which Modify the Photo-periodic Response

1. Temperature

2. Diet

3. Geographical Factors

E. The Genetics of the Photo-periodic Response

F. The Spectral Sensitivity and the Intensity Threshold of the Photo-periodic Response


7. The Photo-periodic Clock

A. Evidence for the Involvement of the Circadian System in Time Measurement

1. Skeleton Photo-periods

2. Night Interruptions in Cycles with an Extended "Night"

3. Tests of the External Coincidence Model

4. Abnormal Light/Dark Cycles

5. Tests of the Internal Coincidence Model

6. Summary: External and Internal Coincidence

B. Evidence for an Hour-glass in Time Measurement

1. Abnormal Light/Dark Cycles

2. Night-interruption Experiments

3. Symmetrical Skeleton Photo-periods

C. Oscillators and Hour-glasses

1. Clocks with Hour-glass and Oscillatory Components

2. Oscillators with Hour-glass Properties


8. The Photo-periodic Counter

A. The Cumulative Effects of Photo-period

B. Interactions between the Photo-periodic Counter and Environmental Variables

1. Temperature

2. Nutrition

C. The "Programming" of the Central Nervous System by Photo-period


9. Other Types of Insect Clock

A. The Time-memory (Zeitgedächtnis) of Bees

B. Time-compensated Sun Orientation

C. Lunar, Semi-lunar and Tidal Rhythms

D. Circannual Rhythms and "Long-range" Timers


10. The Anatomical Location of Photo-receptors and Clocks

A. Clocks Controlling Rhythms of Locomotor and Stridulatory Activity

1. The Location of the Photo-receptors

2. The Location of the Clock

B. Clocks Controlling Rhythms of Eclosion

C. Photo-periodic Clocks

Appendix A. Glossary and List of Symbols Used to Describe Clock Phenomena

Appendix B. List of Insects Exhibiting Rhythmic Activity or Photo-periodic Control

References

Index