Invasive Stink Bugs and Related Species (Pentatomoidea)

372 Invasive Stink Bugs and Related Species (Pentatomoidea)

empty, and collapsed ectodermal sacs and massive and dense fat bodies (Musolin and Numata 2003a;
Esquivel 2009, 2011; Takeda et al. 2010).
The induction of winter adult diapause in the temperate populations of Nezara viridula (e.g., Cotton
Belt of the United States) is controlled by photoperiod (Harris et al. 1984, Seymour and Bowman 1994).
Similar observations are reported for the Osaka (34.7°N, 135.5°E) population, in which induction of
winter adult diapause has been tested under several constant photoperiods at 20 and 25°C (Musolin and
Numata 2003a) and in other regions (Ali and Ewiess 1977, Musolin et al. 2011). A long-day photoperi-
odic response is found: almost all specimens are reproductive under long-day conditions, whereas those
under the short-day conditions are in diapause when examined 60 days after adult ecdysis (Figures 7.7
and 7. 8; Musolin and Numata 2003a; Musolin et al. 2007; also see Chapter 11). At both temperatures, the
photoperiodic response curves are similar and the critical day length for diapause induction falls into
a narrow range close to 12.5 h, suggesting that day length is the dominant factor in diapause induction
(Figure 7.8; Musolin and Numata 2003a). The thermostability of the photoperiodic response within
the tested range of temperatures is similar to that of several other heteropterans, namely Riptortus
pedestris (F.) (= clavatus; Alydidae; Kobayashi and Numata 1995), Arma custos (F.) (Pentatomidae;
Volkovich and Saulich 1995), and Orius minutus (L.) (Anthocoridae; Musolin and Ito 2008; also see
Chapter  11). The opposite situation (i.e., when temperature influences the photoperiodic response
strongly) is reported for many other insect species (Danilevsky 1961, Danks 1987, Saulich and Musolin
2011; also see Chapter 11).
In North American populations of Nezara viridula, the fifth (final) instar is reported to be the most
sensitive to photoperiodic signals for diapause induction (Pitts 1977), whereas the fourth instar is sug-
gested to be more important in a population from Egypt (Ali and Ewiess 1977). Diapausing adults of
N. viridula are sensitive to diapause-terminating long-day signals, whereas reproductive adults can nei-
ther stop their reproductive processes nor switch to diapause in response to short-day stimuli (Musolin
and Numata 2003b, Musolin et al. 2007).
In the Osaka population of Nezara viridula, a marked variation in the incidence of diapause is recorded
under the near-critical photoperiods (L:D 12:12 and 13:11; Figure 7.8; Musolin and Numata 2003a). Both
sexes show photoperiodic response curves of a similar shape and, in most regimes, females exhibit a
higher incidence of diapause than males (Figure 7.8; Musolin and Numata 2003a).

100

80

60

40

20

0

10 11 12 13 14 15 16

Day 60

Day 18 0

Day 21 0

Day 24 0

Photophase, h

Incidence of diapause,

%

FIGURE 7.7 Effect of day length on diapause status and diapause maintenance in female Nezara viridula at 25°C.
Incidence of diapause status was judged by dissection on day 60 after adult emergence. Incidence of diapause maintenance
was judged by coloration of females on days 180, 210, and 240 after adult emergence (nonovipositing deep russet females
were considered to be in diapause). (From D. L. Musolin, Physiological Entomology 37: 309–322, 2012, with permission.)