Entomological Science

Cover image for Vol. 20 Issue 1

Edited By: Masanori J. Toda

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ISI Journal Citation Reports © Ranking: 2016: 39/91 (Entomology)

Online ISSN: 1479-8298

Diapause - a Principal Seasonal Adaptation in Insects Virtual Issue

Diapause – a Principal Seasonal Adaptation in Insects

Diapause – a Principal Seasonal Adaptation in Insects

Edited by Ivo Hodek, Academy of Sciences, Czech Republic

Periods that are suitable for the morphogenetic development and growth of organisms alternate with periods that are unsuitable or even perilous. This is most true for (and most studied in) the regions with temperate climate, but some type of such situation occurs on most land surface, also in the regions with tropical or subarctic climate. A wide range of adaptations evolved in insects (as in other animals). The period of unsuitable conditions may be avoided by migration (“escape in space”) or bridged in a more or less inactive phase (“escape in time”) that has usually an increased survival potential. A general term dormancy has been adopted in the last decades for the expression of various adaptations, ranging from quiescence to diapause. The principal adaptive functions of dormancy (to synchronize the development of active stages with favorable conditions and to enhance survival) are realized best by diapause. In contrast to quiescence diapause is induced by cues (“seasonal tokens”) i.e. signal conditions that herald well ahead the arrival of unfavorable conditions – but do not prevent development.

It would be superfluous to repeat other definitions and list the details of regulatory pathways, as this may be found in the principal compendia, where the most prominent researcher on diapause, Professor Sinzo Masaki is one of authors. However, it might be interesting to follow how our predecessors gradually developed diapause studies, even if my views might be subjective.

In a “pre-history” of diapause studies, the role of photoperiod was ignored and diapause was considered a state of depressed viability due to accumulation of noxious substances. Although this view was rejected, the induction of diapause has long been viewed as a direct impact of unsuitable environmental factors – these drivers were not seen as cues. About ten years after the role of photoperiod was discovered in the study of seasonal forms of aphids, its role as a cue, anticipating safely ahead the seasonal changes, was recognized in insect diapause. These discoveries built the basis for a further very important progress thanks to findings of latitudinal differences of the critical photoperiod on Lepidoptera in Russia and on crickets in Japan. A principal step forwards in the research of diapause termination was represented by the original notion of diapause development as “physiogenesis” 60 years ago: diapause is not a static inhibition (that should be “broken”) but a process which should be completed. In more recent times further steps were made in our understanding of diapause, such as the discoveries of the effect of dynamic photoperiods and of the quantitative response to photoperiod, and the notion of multiple pathways of diapause completion, e.g. by horotelic (spontaneous) and tachytelic (activation) processes.

In the papers assembled in this virtual issue all these gradual achievements in diapause studies have been recognized and in most of them our knowledge of diapause has further been widened and deepened.

Effect of photoperiod on development and growth in a pentatomid bug Dolycoris baccarum

Winter survival and oviposition before and after overwintering of a parasitoid wasp, Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae)
Takeshi TERAOKA, Hideharu NUMATA

Seasonal changes in the reproductive and life-history traits of Chrysomela populi L. (Coleoptera: Chrysomelidae)
Tadashi GOMI, Tomonori KIMURA, Shunpei HIROSE

Seasonal occurrence and diapause induction of a predatory bug Andrallus spinidens (F.) (Heteroptera: Pentatomidae)

Adaptive significance of the recurrent photoperiodic response in a spring-breeding carabid beetle, Carabus yaconinus
Yoshinori SHINTANI, Hideharu NUMATA

Geographic variation in embryonic diapause, cold-hardiness and life cycles in the migratory locust Locusta migratoria (Orthoptera: Acrididae) in China
Seiji TANAKA, Dao-Hong ZHU

Maternal induction of larval diapause and its sensitive stage in the blow fly Lucilia sericata (Meigen) (Diptera: Calliphoridae)
Shin-Ichiro TACHIBANA, Hideharu NUMATA

Species specificity in photoperiodic control of nymphal development in four species of cricket from north-west China
Tetsuo ARAI, Ju-Peng LIU, Chun-Mei HUANG, Xin-Yue CHENG, Yasuhiko WATARI, Makio TAKEDA

Circannual pupation rhythm in the varied carpet beetle Anthrenus verbasci under different nutrient conditions
Yosuke MIYAZAKI, Tomoyosi NISIMURA, Hideharu NUMATA

Seasonal changes of phospholipids in last instar larvae of rice stem borer Chilo suppressalis Walker (Lepidoptera: Pyralidae)
Yohei IZUMI, Chihiro, KATAGIRI, Shoji SONODA, Hisaaki TSUMUKI

Life-history traits related to diapause in univoltine and bivoltine populations of Ypthima multistriata (Lepidoptera: Satyridae) inhabiting similar latitudes Suzuki NORIYUKI, Koji AKIYAMA, Takayoshi NISHIDA

Differentiation in life cycle of sympatric populations of two forms of Hyphantria moth in central Missouri

Aestivation in Pieris brassicae (L.) affects the parasitoid load caused by Cotesia glomerata (L.)

Seasonal life cycles and resource uses of flower- and fruit-feeding drosophilid flies (Diptera: Drosophilidae) in central Japan
Hideyuki MITSUI, Katsura BEPPU, Masahito T. KIMURA

Unity and diversity in the insect photoperiodic mechanism (review article)