556 Invasive Stink Bugs and Related Species (Pentatomoidea)
at sunset or when the geometric center of the sun is 0°50′ below the horizon and ends when
the geometric center of the Sun reaches 6° below the horizon [civil dusk]); many insect species
perceive civil twilights as a part of photophase
Cold hardiness: ability of an organism to survive at low temperature; it can be achieved by three strate-
gies: cryoprotective dehydration, freeze intolerance, and freeze tolerance. Synonym: Cold
tolerance
Cold termination of winter diapause: termination of winter diapause in response to exposure to low
temperatures (usually above 0°C); often considered as a result of the tachytelic process
Cold tolerance: see Cold hardiness
Conditional polyphenism: see Polyphenism
Critical day length: see Critical photoperiod
Critical photoperiod: under field conditions or in the laboratory, photoperiod (i.e., day length) at
which 50% of individuals of a particular population at particular temperature (especially in
the laboratory) demonstrate clearly photoperiodic response (e.g., enter diapause). Synonyms:
Critical day length, Photoperiodic threshold
Cryophase: lower-temperature phase of the thermorhythm in a laboratory experiment
Cryoprotective dehydration: one of three strategies of cold hardiness; survival of subzero tempera-
tures by losing osmotic water to the surrounding environment, so resulting in an increase of the
concentration of their body fluids and, thus, a decline in their melting point (to equilibration
with the ambient temperature); as a result, they cannot freeze (Zachariassen 1985, Bale 2002,
Sinclair et al. 2003)
Crystallization temperature: see Supercooling point
Day length: duration (in hours and minutes) of the light part of a daily cycle (i.e., photophase). Synonym:
Photoperiod (note that day length usually refers to the field situation, whereas photoperiod to
laboratory experiment). Antonym: Night length (i.e., Scotophase). Laboratory photoperiod is
usually indicated as, e.g., L:D 16:8, where L is light period, or photophase (16 hours), and D is
dark period, or scotophase (8 hou rs)
Day-length sensitive stage: see Sensitive stage
Decreasing day length: see Changing day length
Decreasing photoperiod: see Changing day length
Degree-days: a method of estimation of thermal (i.e., temperature) requirements of organisms (popula-
tions, species) or resources of particular locations or regions; total degree-days from an appro-
priate starting date or temperature level are used to understand voltinism of species or develop
pest control strategy; computed as the integral of a function of time that generally varies with
temperature. See Sum of effective temperatures
Development(al) threshold: see Lower development threshold
Diapause: profound, endogenously, and centrally mediated interruption that routes the develop-
mental program away from direct morphogenesis into an alternative diapause program
of succession of physiological events; the start of diapause usually precedes the advent
of adverse conditions, but the end of diapause need not coincide with the end of adversity
(Koštál 2006)
Diapause, forms of: diapause can be of two forms – facultative diapause and obligate diapause
Diapause, seasonal classes of: diapause can be of two seasonal classes – winter diapause and summer
diapause
Diapause, types of: diapause can be linked to four (in Heteroptera – three) ontogenetic (i.e., devel-
opmental) stages and, thus, be of four (in Heteroptera – three) types – embryonic (i.e., egg)
diapause, nymphal (i.e., larval) diapause, pupal diapause (not in Heteroptera), and adult (i.e.,
reproductive, or imaginal) diapause
Diapause development: slow and dynamic changes (i.e., physiological processes) in internal state of
diapausing individual leading to diapause termination
Diapause induction: in species with facultative diapause, such diapause needs to be induced (i.e.,
initiated) by an environmental cue and, thus, this cue needs to be perceived, transmitted, and