Diapause and Quiescence as Two Main Kinds of Dormancy and Their

The paper presents an extention of analytical reviews concerning the dormant stages in life cycles of representatives of the complex group of chelicerate arthropods, named the Acari or Acarina. The previous reviews were devoted to the comparative and evolutionary aspects of dormant stages distribution in life cycles of mites and ticks in comparison to mandibulate arthropods — insects and crustaceans (Belozerov 2006, 2007), and to the diapause and quiescence as two main kinds of dormancy and their significance in life cycles of the acariform mites — Oribatida, Astigmata and Prostigmata (Belozerov 2008). In general, the mentioned papers (together with the presented new one) take into account and are based mainly on the results and conclusions of my many-years experimental studies on ecophysiology of mites and ticks, which were began fifty years ago with gamasid mites (Belozerov 1957, 1958 etc.), and thereafter, five years later, with ixodid ticks in regard to diapause and photoperiodic control of their life cycles (Belozerov 1963, 1964a etc.). In the last review on diapause and quiescence in life cycles of the acariform mites (Belozerov 2008) it was shown that both main functions concerning their seasonality, namely the survival of mite populations during periods of adverse conditions (mainly by means of increased individual resistance), and the seasonal control of their life cycles (through special population adaptations) are enabled in the acariform mites by both kinds of dormancy controlled either endogenously (diapause), or exogenously (quiescence), and also in both ways (through the combination of diapause and quiescence). The latter version is expressed in most obvious way by combinations of diapause and post-diapause quiescence attributed recently in insects (Hodek 1996; Koštal 2006), though the constitutive role of combinations of diapause, quiescence and growth rate in the control of complex insect life cycles was emphasized in special paper of Danks (1991) after preliminary approaching these questions in comprehensive fundamental monographs by Tauber et al. (1986) and Danks (1987). Of special importance in the mentioned paper of Belozerov (2008) is the conclusion that the combination of diapause and post-diapause quiescence ascertained not only in insects, but in many extant acariform mites also, corresponds to the initial ancestral state of dormancy for adaptations of mites and other arthropods to adverse environmental changes, both predictable (seasonal), and non-predictable (irregular). Such a hypothesis, being of definite interest not only for acarologists, gives reasonable explanation also for the retention of such adaptation in extant acariform mites (Prostigmata and Astigmata) from their ancestors, and particularly for possible presence of the same combined seasonal dormancy in extant oribatid mites, as representatives of acariform mites with especially full set of plesiotypic traits (in spite of currently existing controversial interpretations of their nature, either quiescence, or diapause). Here, as it follows from the title of the paper, I concern the same aspects of life history in the Acarina 17 (1): 3–32 © Acarina 2009