Diapause in Pentatomoidea 539
potential of this species as the two generations of E. grisea feed on the two food plants successively
(Melber et al. 1981).
A somewhat similar situation has been found in a few polyphagous pentatomids such as Halyomorpha
halys (= H. mista) (Kawada and Kitamura 1983), Nezara viridula, Piezodorus guildinii, and Euschistus
heros (Panizzi 1997, 2007). Undoubtedly, polyphagy allows many pentatomoids to use several food
plants, produce more generations, and fully utilize local thermal conditions by earlier commencement
of active development in spring and later formation of winter diapause (or developing without any dor-
mancy period in some tropical regions) compared to monophagous true bugs.
Seasonal variation of microhabitat selection is somewhat different than the just described seasonal
food plant change. In tropical Brazil, Phloea subquadrata (Phloeidae) does not need the pronounced
winter diapause; its adults and nymphs are active all year round, but the egg-laying season is restricted
mainly to the warm, rainy season. To deal with the annual sequence of dry and wet seasons, this spe-
cies has evolved a seasonal change in microhabitat selection: under dry weather conditions, phloeids are
found closer to the base of the host tree [Plinia cauliflora (Mart.) Kausel; Myrtaceae] trunks; in the rainy
season, the bugs climb and live higher on the same tree (Salomão and Vasconcellos-Neto 2010).
11.10 Conclusions
The above review of diapause in the experimentally studied pentatomoids (82 species), mostly from the
Temperate Zone, has revealed no distinct trends in the type (embryonic, nymphal, or adult), form (obligate
or facultative), or seasonal class (winter or summer) of diapause in particular taxa within the superfamily.
Earlier analysis of seasonal development of Pentatomidae resulted in a similar conclusion; evolution
of their seasonal adaptations does not correspond precisely to the phylogeny of the family (Saulich and
Musolin 2012). However, similar complexes of seasonal adaptations might be formed within individual
genera (e.g., Palomena with an obligate diapause and photoperiodic control of nymphal growth rates, or
Euschistus with photoperiodic control of body color polyphenism), small tribes (e.g., Aeliini), or even
subfamilies (e.g., Podopinae). At the same time, the large subfamily Pentatominae, despite being a poly-
phyletic taxon, is quite uniform in that most of the species have facultative winter adult diapause.
The seasonal changes of body coloration are more widespread in Pentatomidae (mostly those hav-
ing winter adult diapause) than in other taxa of true bugs. However, other seasonal adaptations that are
common in some heteropteran taxa such as wing size/wing muscle seasonal polyphenism (Saulich and
Musolin 2007a,b) have been found so far only in one pentatomoid species (burrower bug Scaptocoris
carvalhoi; Nardi et al. 2008).
Knowledge of ecology and seasonal development of a species may in some cases help clarify its
taxonomic position. For example, Dybowskyia reticulata is considered a member of the tribe Tarisini by
some authors (Vinokurov et al. 2010) and a member of the Graphosomatini by others (Gapon 2008). In
its ecological characteristics, D. reticulata resembles species of Graphosomatini and this ecological trait
should be taken into consideration in its classification.
In general, despite intensive studies of seasonal adaptations in pentatomoids and other heteropteran
taxa in recent decades, diapause and ecological mechanisms of its control have been studied in less than
1% of the known species of true bugs. Clearly, more research is needed.
The role that individual seasonal adaptations and their complexes play in the structure of the species’
seasonal cycle will be discussed in detail in Chapter 12.
11.11 Acknowledgments
Our research on heteropteran diapause was aided by the fruitful collaboration with many colleagues, includ-
ing Nikolai Goryshin and Tatyana Volkovich (Department of Entomology, Leningrad / Saint Petersburg
State University, Saint Petersburg), Hideharu Numata (Graduate School of Science, Kyoto University,
Kyoto), Kiyomitsu Ito (National Agricultural Research Center for Hokkaido Region, Sapporo), and Kenji