Diapause in Pentatomoidea 499
received much attention in studies of diapause, although the number of species studied and the depth of
the research have been noticeably less than in the Lepidoptera and Diptera.
The Pentatomoidea is one of the largest superfamilies of Heteroptera (see Chapter 2). Species in this
superfamily have a wide range of seasonal adaptations, and many are economically important (Schuh
and Slater 1995; Musolin and Saulich 1996a; McPherson and McPherson 2000; Panizzi et al. 2000;
Saulich and Musolin 2007a,b, 2012, 2014; Henry 2009; Musolin 2012; Panizzi and Grazia 2015). Despite
the relatively large size of pentatomoid bugs and the availability of specimens, only a few species that
are economically important have been studied in detail in terms of seasonal cycles and seasonal develop-
ment. The Pentatomidae is the third largest family of the Heteroptera. It comprises about 4,840–4,950
species (over 10% of the entire order) that are grouped into 900–940 genera and 8–11 subfamilies (Gapon
2008, Henry 2009; Vinokurov et al. 2010, see Chapter 2). Within this family, representatives of only
three subfamilies (i.e., Asopinae [= Stiretrinae], Podopinae, Pentatominae) have been studied in terms of
diapause, seasonal cycles, and seasonal development.
In this chapter, we review and discuss specific traits of diapause and associated phenomena in pentato-
mids and include rare examples from other (less well studied in this respect) families of Pentatomoidea.
11.2 Diapause as a Form of Dormancy in Pentatomoidea
Diapause is one of the most widely spread forms of insect dormancy. Vast literature is devoted to insect
diapause, including its physiology, ecological functions, and, recently, genetics (Danilevsky 1961, Tauber
et al. 1986, Danks 1987, Saulich and Volkovich 2004, Denlinger 2008, Denlinger and Lee 2010). In this
section, we provide a brief overview of what is known about diapause in Pentatomoidea.
Diapause now is understood as a complex and dynamic process. In the less common cases, diapause
is obligate (or obligatory), and the initiation of such diapause needs no external (i.e., exogenous) signals
or cues because it represents a fixed and genetically strongly controlled component of the ontogenetic
program, which is realized regardless of the environmental conditions in each generation. In more wide-
spread cases, however, diapause is facultative and external (i.e., exogenous) token stimuli are necessary
to induce the diapause state and, thus, individuals can switch between two ontogenetic alternatives, i.e.,
direct (or active) development or diapause (Koštál 2006; see Section 11.2.3 for more details).
11.2.1 Phases of Diapause
Many different views on the stages or phases of diapause have been presented in the literature (see Danilevsky
1961; Saunders 1976; Tauber et al. 1986, Hodek 1996, 2002; Saulich and Volkovich 2004 for reviews).
Recently Koštál (2006) suggested a simplified model of diapause which consisted of three major phases:
prediapause, diapause, and postdiapause (Figure 11.1).
During the prediapause phase, direct ontogenetic development (morphogenesis) continues. This
phase has two subphases in the species with facultative diapause and most likely only one in the species
with obligate diapause. In the first group (i.e., the species with facultative diapause), diapause needs to be
induced by an environmental cue and, thus, this cue needs to be perceived, transmitted, and interpreted
by the neurohormonal system of the individual. This cue switches the ontogenetic pathway from direct
development to diapause, and this period is called the induction subphase. At the same time, in the
species with obligate diapause, there is no induction subphase because diapause is not induced. In other
words, in the species with obligate diapause, this diapause is a necessary step (i.e., arrest) of development
in each generation. Another part of the prediapause phase is a preparation subphase, during which
individuals undergo behavioral and/or physiological change (e.g., acquire energy resources such as lipids
or in some cases – starch, etc.), void the digestive system (gut), migrate and/or simply look for protective
microhabitats (often called hibernaculum or hibernacula), sometimes change body color and so on.
During the next and more prolonged diapause phase, direct active development is endogenously (i.e.,
internally) arrested, and an alternative program of still mostly unknown physiological events proceeds.
The diapause phase can be divided into three subphases. During the initiation subphase, direct devel-
opment ceases, deep physiological preparations take place, and intensity (or deepness) of diapause may