Invasive Stink Bugs and Related Species (Pentatomoidea)

580 Invasive Stink Bugs and Related Species (Pentatomoidea)

The sloe bug, Dolycoris baccarum (L.), is a widespread Palaearctic pentatomid with a multivoltine
seasonal cycle. Its populations from Russia (Kamenkova 1958, Perepelitsa 1971), Kazakhstan (Asanova
and Iskakov 1977), the Czech Republic (Hodek 1977, Babrakzai and Hodek 1987, Hodek and Hodková
1993), Norway (Conradi-Larsen and Sømme 1973, 1978; Hodková et al. 1989), Israel (Yathom 1980),
Turkey (Karsavuran 1986), and Japan (Nakamura and Numata 2006) have been studied in detail. The
species produces only one generation per year in the north of its range (e.g., Norway) and two generations
in the temperate latitudes (e.g., Voronezh, Russia) and in southern regions (e.g., Krasnodar in Russia;
Almaty in Kazakhstan).
The local population of Dolycoris baccarum on Cyprus Island develops in one generation because
its seasonal cycle includes summer diapause lasting from June to November. The overwintered adult
bugs migrate in March from their hibernation quarters to the plains. In April–May, they mate, and
the females lay eggs. The nymphs pass through five stadia and become adults, which migrate in June to
their estivation quarters in the mountains at latitudes of about 1,300–1,500 meters a.s.l. In December,
the adult bugs move to lower places (about 1,200 meters a.s.l.), where they overwinter until the end of
March (Krambias 1987).
In more northern multivoltine populations of Dolycoris baccarum, which lack summer diapause,
induction of the winter adult diapause is controlled by a long-day type PhPR: the adults actively develop
at long day and enter diapause at short day. Sensitivity to day length is present in the nymphs starting
from the fourth instar; however, the influence of short-day conditions only on the fifth instars and adults
is sufficient for diapause induction in 100% of individuals (Perepelitsa 1971).
Geographic variation of the parameters of PhPR of diapause induction in this species was first discovered
during a comparative study of its populations from Voronezh (51.7°N) and Krasnodar (45°N; Perepelitsa
1971). The difference between the values of critical photoperiod was about 1 hour (Figure 12.11).
In Krasnodar, emergence of adults of the first generation starts on June 20 and continues through
all of July (Kamenkova 1958). Because the natural day length during this period considerably exceeds
the critical day length of adult diapause induction of the local population measured in the laboratory
(Perepelitsa 1971), all the adults of the first generation remain physiologically active and participate in
reproduction. The critical day length including half the civil twilights (15 hours 30 minutes) is reached
at the latitude of Krasnodar at the end of July, which is exactly when fourth instars (the day-length-
sensitive stage) of the second generation emerge. The subsequent development of the second generation
of Dolycoris baccarum proceeds under short-day conditions. By September 1, the day length decreases
to 14 hours of light, which ensures the onset of diapause in all the adults.
In Voronezh, which is positioned 6.7 degrees to the north of Krasnodar, diapause formation in
Dolycoris baccarum starts 1 hour later, at a day length of 16 hours 30 minutes, in accordance with

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Sum of eff

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AprilMay

G1 G2 G3

Preoviposition period G4

Eggs + nymphs

JuneJuly August September

FIGURE 12.10 A scheme of seasonal development of the pentatomid Piezodorus hybneri in Kumamoto, southwestern
Japan (32.9°N), based on the determined thermal parameters of development. G1–G4 are the consecutive generations of the
species. (From H. Higuchi, Applied Entomology and Zoology 29: 585–592, 1994, with permission.)