Life Cycle Development
73
Notwithstanding similarities in life history characteristics such as precocity and circumscribed oviposition, the timing of the life cycles of the three
oribatid species appears species specific and differs in the timing of different
activities. S. cf.latipes, which inhabits sheltered microsites underneath Quercus coccifera shrubs, can develop during summer. The eggs of A. oudemansi,
which is restricted to semi-sheltered micro sites close to the shrubs but not
underneath them, withstand summer drought in a state of dormancy and
develop rapidly in autumn. Finally, the eggs of P. alli/era are laid in open sites
in autumn and in spring. After emergence in late spring, the larvae overcome
summer drought by remaining dormant and develop rapidly in the autumn.
Generalising the above considerations, it can be concluded that the life
cycle and development of microarthropods in Mediterranean regions is
under the control of strongly and largely predictable variations in climate. In
specific cases, other external factors including edaphic ones also become
important (Asikidis and Stamou 1992). Intrinsic factors, such as inter- and
intraspecific competition, are in all probability oflesser importance in the life
cycle and development of microarthropods. Analogous conclusions have
been reported for animals living in other severe environments such as the
Antarctic (e.g. Block 1985).
5.3.2
Life Cycle Development of Long-Lived Arthropods
The timing of the life cycle and the development of long-lived arthropods
also appear to be species specific. For exainple, in the Mediterranean regions
of Israel, the isopod Philoscia muscorum peaks in winter, Metoponorthus
pruinosus in early spring, and A. officinalis in late spring (Warburg 1987a).
However, like those of their short-lived relatives, the life cycle and development of long-lived arthropods in Mediterranean regions are synchronised
with both seasonal and interannual cycles. Figure 5.6 shows a diagram of the
life cycle and development of the diplopod A. t. judaicus in mesic and xeric
habitats of Israel. Egg laying and development of the most vulnerable younger stadia occur during short periods. After 1 year the animals are at stages IV
and V in the mesic and xeric environments, respectively. Animals in the subsequent stadia moult once a year in the mesic habitat and three times a year
in the xeric habitat.
Obviously, the life cycle development of macroarthropods is realised differently under different habitat conditions. However, the sequential occurrence of different phenophases within short time periods - ensuring synchronisation with interannual cycles - is invariably recorded. The life cycle of
the millipede G. balcanica on Hortiatis is illustrative. Within a period of 3.5
years, only one successful breeding was recorded in April/July 1983. The animals normally attain maturity after 3-3.5 years, and a second generation was
initiated 3 years later in April/July 1986. As could be shown, unsuccessful
73
Notwithstanding similarities in life history characteristics such as precocity and circumscribed oviposition, the timing of the life cycles of the three
oribatid species appears species specific and differs in the timing of different
activities. S. cf.latipes, which inhabits sheltered microsites underneath Quercus coccifera shrubs, can develop during summer. The eggs of A. oudemansi,
which is restricted to semi-sheltered micro sites close to the shrubs but not
underneath them, withstand summer drought in a state of dormancy and
develop rapidly in autumn. Finally, the eggs of P. alli/era are laid in open sites
in autumn and in spring. After emergence in late spring, the larvae overcome
summer drought by remaining dormant and develop rapidly in the autumn.
Generalising the above considerations, it can be concluded that the life
cycle and development of microarthropods in Mediterranean regions is
under the control of strongly and largely predictable variations in climate. In
specific cases, other external factors including edaphic ones also become
important (Asikidis and Stamou 1992). Intrinsic factors, such as inter- and
intraspecific competition, are in all probability oflesser importance in the life
cycle and development of microarthropods. Analogous conclusions have
been reported for animals living in other severe environments such as the
Antarctic (e.g. Block 1985).
5.3.2
Life Cycle Development of Long-Lived Arthropods
The timing of the life cycle and the development of long-lived arthropods
also appear to be species specific. For exainple, in the Mediterranean regions
of Israel, the isopod Philoscia muscorum peaks in winter, Metoponorthus
pruinosus in early spring, and A. officinalis in late spring (Warburg 1987a).
However, like those of their short-lived relatives, the life cycle and development of long-lived arthropods in Mediterranean regions are synchronised
with both seasonal and interannual cycles. Figure 5.6 shows a diagram of the
life cycle and development of the diplopod A. t. judaicus in mesic and xeric
habitats of Israel. Egg laying and development of the most vulnerable younger stadia occur during short periods. After 1 year the animals are at stages IV
and V in the mesic and xeric environments, respectively. Animals in the subsequent stadia moult once a year in the mesic habitat and three times a year
in the xeric habitat.
Obviously, the life cycle development of macroarthropods is realised differently under different habitat conditions. However, the sequential occurrence of different phenophases within short time periods - ensuring synchronisation with interannual cycles - is invariably recorded. The life cycle of
the millipede G. balcanica on Hortiatis is illustrative. Within a period of 3.5
years, only one successful breeding was recorded in April/July 1983. The animals normally attain maturity after 3-3.5 years, and a second generation was
initiated 3 years later in April/July 1986. As could be shown, unsuccessful