CHAPTER 4
Activity Patterns
4.1
Daily Patterns
The physiological responses to environmental constraints described in previous sections control the activity of arthropods in the field. The dailyactivity of most animals is controlled by free-running biological clocks, although
it is continuously modulated by changes in abiotic variables as well (Cloudsley-Thompson 1982). For example, the activity of some beetle species from
Mediterranean pasturelands is determined by an endogenous circadian rhythm
as well as by light intensity (Mena et al. 1989). The endogenous rhythm induces a preactive state, while the onset of activity itself is light dependent.
Diurnal species (11 out of 19) were active under light intensities beyond 110 lx,
crepuscular ones (three species) were active under a light intensity ranging
from 110 to 0 lx, whilst four exclusively nocturnal species were also recorded.
The flight activity of crepuscular and nocturnal beetles does not appear to
be influenced by temperature or humidity. In contrast, temperature determines the flight activity of diurnal species. In winter and spring maximum
activity occurs during the afternoon, whereas in summer some species shift
their time of activity towards the morning following a "maxithermal strategy", i.e. they shift their activity to a time at which the maximum sublethal
temperature occurs (Mena et al. 1989). Seasonal shifting in daily activity has
also been described in diplopods by Crawford et al. (1987). Activity in spring
lasts for most of the daylight hours, while in summer the animals are nocturnal. In general, the daily activity patterns of most Mediterranean arthropods
follow the climatic variables of the seasons.
Analogous to their desert counterparts, diurnal activities of Mediterranean arthropods can also be conditioned by behavioural thermoregulation
such as migration to sites of preferred temperatures or basking in full sunlight etc. (Wooten et al. 1975; Cloudsley-Thompson 1982; Crawford et al. 1987;
Hopkin and Read 1992). Thus, differences among diurnal rhythms of different species under different temperature regimes are usually correlated with
habitat properties. For example, differences in the activity patterns of the
Activity Patterns
4.1
Daily Patterns
The physiological responses to environmental constraints described in previous sections control the activity of arthropods in the field. The dailyactivity of most animals is controlled by free-running biological clocks, although
it is continuously modulated by changes in abiotic variables as well (Cloudsley-Thompson 1982). For example, the activity of some beetle species from
Mediterranean pasturelands is determined by an endogenous circadian rhythm
as well as by light intensity (Mena et al. 1989). The endogenous rhythm induces a preactive state, while the onset of activity itself is light dependent.
Diurnal species (11 out of 19) were active under light intensities beyond 110 lx,
crepuscular ones (three species) were active under a light intensity ranging
from 110 to 0 lx, whilst four exclusively nocturnal species were also recorded.
The flight activity of crepuscular and nocturnal beetles does not appear to
be influenced by temperature or humidity. In contrast, temperature determines the flight activity of diurnal species. In winter and spring maximum
activity occurs during the afternoon, whereas in summer some species shift
their time of activity towards the morning following a "maxithermal strategy", i.e. they shift their activity to a time at which the maximum sublethal
temperature occurs (Mena et al. 1989). Seasonal shifting in daily activity has
also been described in diplopods by Crawford et al. (1987). Activity in spring
lasts for most of the daylight hours, while in summer the animals are nocturnal. In general, the daily activity patterns of most Mediterranean arthropods
follow the climatic variables of the seasons.
Analogous to their desert counterparts, diurnal activities of Mediterranean arthropods can also be conditioned by behavioural thermoregulation
such as migration to sites of preferred temperatures or basking in full sunlight etc. (Wooten et al. 1975; Cloudsley-Thompson 1982; Crawford et al. 1987;
Hopkin and Read 1992). Thus, differences among diurnal rhythms of different species under different temperature regimes are usually correlated with
habitat properties. For example, differences in the activity patterns of the