Invasive Stink Bugs and Related Species (Pentatomoidea)

586 Invasive Stink Bugs and Related Species (Pentatomoidea)

as  an  about 20-day-long delay in gonads’ maturation in adults in summer. Both diapauses terminate
spontaneously: nymphal diapause terminates in early spring after overwintering and adult diapause ter-
minates in mid-summer (Tanaka 2002, Tanaka et al. 2002).
Overwintered nymphs of Poecilocoris lewisi molt to the adult stage in May. Then, in response to the
long-day conditions at that time, all females enter summer diapause and start oviposition only after
termination of this estivation in July, when seeds of dogwood become available (Figure 12.17). Thus,
summer adult diapause synchronizes emergence of nymphs of the bug’s first summer generation with
the period when food is available and fresh. Earlier nymphs of this first summer generation reach the

100

50

0

50

40

30

20

10

10 11 12 13 14 15 160

Photoperiod, h

Incidence of diapause,

%

Pr

eo

viposition period, da

ys

FIGURE 12.16 Two photoperiodic responses of the clown stink bug, Poecilocoris lewisi, from Osaka (34.7°N), Japan.
Induction of facultative winter nymphal diapause: open circles, left vertical axis; induction of facultative summer adult dia-
pause in females: closed circles and right axis (preoviposition period is shown as mean ± SD). Nymphs were reared to adults
and then maintained at 25°C under constant photoperiodic conditions (indicated under the horizontal axis). (Modified
from S. I. Tanaka, C. Imai, and H. Numata, Applied Entomology and Zoology 37: 469–475, 2002, with permission.)

16

1996

1995

10

II

I

20

IV VVIVII VIII IX X

Te

mp

erature, °C

30

1

2

15

Da

y leng

th,

h

14

13

OG

Eggs

Diapause

Diapause

Nymphs

Adults

Months

FIGURE 12.17 Seasonal development of the clown stink bug, Poecilocoris lewisi, in Osaka (34.7°N), Japan. The upper
panel shows the day length including 1 hour of the twilight period ( 1 ) and daily mean temperatures recorded at an outdoor
experimental cage in 1995 and 1996 ( 2 ). The shaded bar shows the critical day length for the induction of nymphal and
adult diapauses. The lower panel shows the possible pathways of the species’ life cycle in Osaka. OG, overwintered genera-
tion; I is the first generation (full); II is the second generation (partial); horizontal hatching shows periods of diapauses in
nymphs and adults of different generations; an arrow shows that the second generation (partial) is produced by the non-
diapausing fraction of the first generation. (Modified from S. I. Tanaka, C. Imai, and H. Numata, Applied Entomology and
Zoology 37: 469–475, 2002, with permission.)