Invasive Stink Bugs and Related Species (Pentatomoidea)

Seasonal Cycles of Pentatomoidea 581

geographic variation of the critical day length of diapause induction (Perepelitsa 1971). Considering the
civil twilights, such a day length at the latitude of Voronezh is observed on July 20; at the end of August
the day length decreases to 15 hours, which induces diapause in all the bugs.
Thus, the seasonal development of Dolycoris baccarum populations in their natural habitats proceeds
in perfect agreement with the parameters of the PhPR of diapause induction determined in laboratory
experiments. The populations develop in two generations. The timing of diapause induction is deter-
mined by hereditary properties of the PhPR of diapause induction of each geographic population and
corresponds to the local conditions in the best way possible. The Krasnodar and Voronezh populations
of D. baccarum develop without summer diapause.
The existence of geographic variation of the PhPR of diapause induction in Dolycoris baccarum was
also clearly demonstrated during a comparative study of its populations from Japan (Figure 12.12):
those from Osaka (34.7°N) and Hokkaido Island (44.2°N). The critical photoperiod of diapause induction

100

90

80

70

1

2

60

50

40

30

20

10

0

12 13 14 15

Photoperiod, h

Incidence of diapause,

%

16 17 18

FIGURE 12.11 Geographic variation of the photoperiodic response of diapause induction in the sloe bug, Dolycoris
baccarum. Populations tested: 1 – Krasnodar (45°N) and 2 – Voronezh (51.7°N), both in Russia. Nymphs were reared and
then adults were maintained at 28°C under constant photoperiodic conditions (indicated under the horizontal axis). (Data
from L. V. Perepelitsa, Byulleten’ Vsesojuznogo Instituta Zashchiti Rasteniy [Bulletin of the All-Union Institute of Plant
Protection] 21: 11–13, 1971.)

100

50

0

12 14 16 18

Photoperiod, h

Incidence of diapause,

%

FIGURE 12.12 The photoperiodic response of facultative winter adult diapause induction in different geographic popula-
tions of the sloe bug, Dolycoris baccarum. Circles: population from Osaka (34.7°N), triangles: population from Hokkaido
Island (44.2°N), both in Japan; black symbols: males; light symbols: females. Nymphs were reared to adults and then
maintained at 25°C under constant photoperiodic conditions (indicated under the horizontal axis). (From K. Nakamura and
H. Numata, Applied Entomology and Zoology 41: 105–109, 2006, with permission.)