Invasive Stink Bugs and Related Species (Pentatomoidea)

Seasonal Cycles of Pentatomoidea 569

The seasonal development of Picromerus bidens under natural conditions was studied experimen-
tally in Belgorod Province, Russia (50°N). The results allowed us to characterize the seasonal cycle of
this bug in the temperate climate of the forest-steppe zone (Figure 12.2). The field experiment showed
that nymphs of this species hatched in spring from overwintered eggs. Long days slightly retarded
nymphal development. The final molt occurred in June but oviposition was delayed until the second half
of August so that females laid diapausing eggs only in autumn (Musolin and Saulich 2000).
This kind of seasonal cycle is unusual for pentatomoids, and its relatively simple pattern seems to
leave no place for photoperiodic control. However, it was experimentally shown that the seasonal cycle
of Picromerus bidens included not one but two distinct dormancy periods: the obligate winter embry-
onic diapause and the facultative summer adult diapause (i.e., reproductive diapause, or estivation; see
Chapter 11 for details).
The onset of facultative summer adult diapause in Picromerus bidens is controlled by a short-day
type photoperiodic response of diapause induction of the adults (Figure 12.3). Under photoperiodic

10

8

6

4

2

0

IV VVIVII VIII IX XXI

60

50

40

30

20

10

0

Months

Numb

er of individuals

Numb

er of individuals

, %

FIGURE 12.1 Findings of adults of the predatory pentatomid Picromerus bidens in the field in Great Britain (the right
ordinate axis and columns; n > 300; data from D. Leston. The Entomologist’s Monthly Magazine 91: 109, 1955) and
early-season findings of adults in various regions of Russia (the left ordinate axis and circles; based on the records in
the collections of the Zoological Institute, the Russian Academy of Sciences, Saint Petersburg; data from D. L. Musolin.
Ph. D. Dissertation in Biology. Saint Petersburg, Russia, 1997; late-season records of adults in Russia are not shown).
The early-season findings of adults likely represent overwintered individuals that had been parasitized by tachinid flies
of the subfamily Phasiinae (Diptera: Tachinidae) in the previous late summer or autumn, did not reproduce and then die
before winter, but, in fact, overwintered and survived until April–June (see more explanation in Section 12.2.1.1).

IV

OOOOOOOO

OOOOOOOOOOOOOOOOOOOO

Diapause of eggs, maintained

by low temperature

SD stimulation

of oviposition

LD delay of reproduction

(estivation)

VVIVII VIII IX XXIXII

––––––

+++++++++++++++

OOO eggs – – – nymphs +++ adults

FIGURE 12.2 Seasonal development of the predatory pentatomid Picromerus bidens in Belgorod Province, Russia
(50°N). LD is long day; SD is short day; months are indicated on the top of the figure see text for explanation. (Data from
D. L. Musolin. Ph. D. Dissertation in Biology. Saint Petersburg, Russia, 1997.)