While these changes are more apparent over seasons, daily food availability may also change as is documented in the case of various plant-pollinator and prey-predator interactions ( Bloch et al., 2017) ( Kronfeld-Schor et al., 2017). Similarly, biotic factors such as food resources may also serve as time cues to the clock of many animals ( Hau and Gwinner, 1996) ( Sharma et al., 2000) ( Frisch and Aschoff, 1987).įood resources frequently undergo changes in quality and quantity. Abiotic factors that cycle with time of day such as light and temperature serve as time cues or “zeitgebers” to the clock ( Pittendrigh, 1960) ( Johnson et al., 2003). This is achieved by the process of entrainment which is the ability of the clock to synchronize to cyclic cues in the environment. These findings highlight that food cyclicity by itself may not be a potent zeitgeber but may act in unison with other abiotic factors like light and temperature to help flies time their activity appropriately.Ĭircadian clocks integrate cues from the environment and temporally regulate physiological and behavioural programs to aid animals fulfill their daily needs by anticipating cyclic changes in their day-to-day environment and time their physiology accordingly (Dunlap, 2003).

Additionally, T-cycle experiments resulted in minor period changes during FS treatment. However, we find that starvation induced hyperactivity causes masking which results in phase changes. Taken together these results show that external food availability cycles do not entrain the activity/rest rhythm of fruit flies. We also found that flies subjected to T21 and T26 FS cycles were unable to match period of the activity rhythm to short or long T-cycles.

We found that phase control, which is a property integral to entrainment, was not achieved despite increasing starvation duration of FS cycles (FS12:12, FS10:14 and FS8:16). By subjecting flies to cyclic food availability i.e., feeding/starvation (FS) cycles, we provided food cues contrasting to the preferred activity times and observed if this imposed cycling in food availability could entrain the activity/rest rhythm. As the locomotor activity of an organism is related to its disposition to acquire food, and peak feeding in fruit flies has been shown to occur at a particular time of the day, we asked if cyclic food availability can entrain their rhythmic activity. Since both these aspects are subject to change over time, these behaviours exhibit rhythmicity in occurrence. Foraging and feeding are indispensable for survival and their timing depends not only on the metabolic state of the animal but also on the availability of food resources in their environment.

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