Figure 3.

Input and Output of the circadian clock in D. melanogaster (left) and A. mellifera (right). Relevance of input signals to the clocks differs between species, so that light appears to be most important for the fly clock, but social signals out rule light signals in entraining the bee clock. Many output behaviors are common among different insects (e.g., locomotion, sleep, mating, metabolism, and foraging), but others are limited to or more pronounced in some species (e.g., eclosion in Drosophila and time-place-memory, sun compass orientation or task-related plasticity in circadian behavior in Apis). Although D. melanogaster does not exhibit pronounced diapause, basic mechanisms in clock regulation involved in dormancy appear to be shared between this fly and diapausing fly species. Similarly, A. mellifera does not go into diapause, but it may be that the honey bee exhibits some residual photoperiodic function in initiating dormancy behavior, because solitary bees display pronounced diapause.