Seasonal Cycles of Pentatomoidea 595
oligophages, they faced a shortage of food. The research programs finally were stopped due to lack of
positive applicable results.
However, examination of wild thickets of the common ragweed Ambrosia artemisiifolia L. (Asteraceae)
in Krasnodar Territory in May 2008 revealed numerous nymphs of Perillus bioculatus (with field den-
sity up to 20 individuals/m^2 ) that were feeding actively on different stages of the ragweed leaf beetle,
Zygogramma suturalis F. (Coleoptera: Chrysomelidae) (Ismailov and Agasieva 2010). These nymphs prob-
ably originated from occasional individuals released in the course of the early research programs that
had survived since that time as small inconspicuous populations in some favorable habitats. Later, when
additional suitable prey species appeared (in particular, the ragweed leaf beetle), the pentatomids became
naturalized and dispersed over the south of Russia. According to Ismailov and Agasieva (2010), P. biocu-
latus also fed on the larvae of the ragweed moth, Tarachidia candefacta Hübner (Lepidoptera: Noctuidae);
this fact contradicts the previous characteristic of this species as a narrow oligophage. The ragweed moth is
a species new to Europe, which also was introduced intentionally into Russia in the 20th century to control
common ragweed; the prospects of its naturalization as an agent of ragweed control were studied on the
Black Sea coast of the Caucasus (Nayanov 1973, Esipenko 2012). As a result of this introduction event (and
possibly some other cases of invasion), the ragweed moth has become a common species in the steppe zone
of the south of Russia and Ukraine (Klyuchko et al. 2004, Klyuchko 2006, Poltavsky and Artokhin 2006).
For Perillus bioculatus, deficiency of food resources after the end of overwintering apparently became
a serious obstacle during the initial stage of introduction. Emergence of a new food source in the form
of Tarachidia candefacta and Zygogramma suturalis removed the limiting action of the trophic fac-
tor. Further establishment of P. bioculatus proceeded successfully because of the good match of the
Canadian population’ parameters of the PhPR of diapause induction to the photo-thermal environmental
conditions of southern Russia and Ukraine: P. bioculatus can successfully enter facultative winter adult
diapause in a timely manner in this part of its secondary range.
12.6 Conclusions
Detailed consideration of the published data on the seasonal cycles of insects in general, and Pentatomoidea
in particular, is impeded by the scarcity of experimental data that are needed for proper analysis of the
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Photoperiod, hIncidence of diapause,%^321FIGURE 12.22 The effect of temperature on the photoperiodic response of diapause induction in the predatory pentato-
mid Perillus bioculatus from the southwest of Slovakia (about 45°N). Nymphs were reared to adults and then maintained
under constant photoperiodic conditions (indicated under the horizontal axis) at constant temperatures of 24°C (open
circles and solid line 1 ), 27°C (closed circles and solid line 2 ) or under the natural thermorhythm with amplitude 26.4°C
(photophase) to 13.7°C (scotophase) and the mean temperature of 19.1°C (closed circles and dashed line 3 ). (From T. A.
Volkovich, L. I. Kolesnichenko, and A. Kh. Saulich, Entomological Review 70: 68–80, 1991, with permission.)